basic training guide v6

RecurDyn™

Basic Tutorial

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Edition Note These documents describe the release information of RecurDyn™ V. 6.21.

3D Slider Crank Tutorial Engine with Propeller Tutorial Pinball Ball Return

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Table of Contents Getting Started........................................................................................... 5

Objective .............................................................................................. 5 Audience .............................................................................................. 6 Prerequisites ........................................................................................ 6 Procedures ........................................................................................... 6

Setting Up Your Simulation Environment................................................... 7 Task Objective...................................................................................... 7 Starting RecurDyn ................................................................................ 8 Understanding the Interface ............................................................... 10 Changing the Gravitational Force Direction........................................ 13 Changing the Working Plane.............................................................. 13

Creating Geometry .................................................................................. 15 Task Objective.................................................................................... 15 Modeling the Ground Bracket............................................................. 16 Saving Your Model ............................................................................. 23 Modeling the Crank ............................................................................ 24 Saving Your Model ............................................................................. 33 Creating the Connecting Rod ............................................................. 32 Modeling the Slider............................................................................. 35 Saving Your Model ............................................................................. 41

Creating Joints......................................................................................... 43 Task Objective.................................................................................... 43 Creating the Revolute Joint ................................................................ 44 Adjusting the Icon and Marker Size.................................................... 45 Creating Two Spherical Joints............................................................ 45 Creating the Translational Joint .......................................................... 47 Creating a Motion on the Revolute Joint............................................. 48

Performing Analysis ................................................................................. 51 Task Objective.................................................................................... 51 Performing Dynamic/Kinematic Analysis ............................................ 52

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Working with Animations.......................................................................... 53 Task Objectives.................................................................................. 53 About the Animation Toolbar .............................................................. 54 Playing Animations............................................................................. 54 Saving the Animation as an AVI File .................................................. 55 Tracing the Paths of a Point on the Moving Bodies ............................ 56

Plotting..................................................................................................... 61 Task Objective.................................................................................... 61 Creating a Plot.................................................................................... 62 Plotting in Multiple Panes ................................................................... 63 Loading an Animation......................................................................... 64

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Chapter

1 Getting Started

Objective In this introductory tutorial, you will learn how to:

Set up a model with the correct units and environment

Create bodies with geometric detail

Add joints and associated input motions

Analyze the model to investigate the effects of motion and forces on it.

Communicate the results of your simulation as:

X-Y plots

Animations that can be played interactively within RecurDyn

AVI files that can be inserted into PowerPoint presentations

The target model is a 3D slider-crank mechanism. This mechanism is used to convert an input rotary motion to an output translational motion. You will see how the combination of moving bodies and four kinematic joints can produce a complex relationship between the input and output motions.

5

Getting Started 3D Slider Crank Tutorial

Audience This tutorial is an excellent starting point for the engineer who is using RecurDyn for the first time. The basic tasks that are needed for all simulations are explained carefully.

Prerequisites Because this is an introductory tutorial, we assume that you have no prior experience with RecurDyn. We assume that you have a basic knowledge of physics.

Procedures The tutorial is comprised of the following procedures. The estimated time to complete each procedure is shown in the table.

Procedures Time (minutes)

Simulation environment setup 5

Geometry creation 35

Joint creation 10

Analysis 5

Animation/AVI 10

Plotting 10

Total: 75

Estimated Time to Complete This tutorial takes approximately 75 minutes to complete.

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Chapter

2 Setting Up Your Simulation Environment

Task Objective Learn how to set up the simulation environment, including units, materials, gravity, and the working plane.

Estimated Time to Complete 5 minutes

7

Setting Up Simulation Environment 3D Slider Crank Tutorial

Starting RecurDyn To start RecurDyn and create a new model:

1. On your Desktop, click the RecurDyn tool.

RecurDyn starts up and the New Model dialog box appears.

2. Enter the name of the new model as Slider_Crank_3D.

3. Leave the units at the default values.

4. Click OK.

Tip: Allowed Characters for Model Name You cannot use spaces or special characters in the model name. You can use the underscore character to add spacing to improve the readability of the name.

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Tip: How to set user material library If you want to use a user material, you can import a bin file that RecurDyn exports (refer to the Material Property command under the Subentity menu.)

To import a user material:

1. In the New Model dialog box, click User Material Library.

2. Click Add to select a bin file, and then select Open.

3. Click OK.

Tip: Other ways to create a new model To create a new model in RecurDyn, you can do one of the following:

In the tool bar, click the New tool.

From the File menu, click New.

Use the shortcut key (Ctrl + N).

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Understanding the Interface The RecurDyn interface consists of several basic areas as shown in the figure below. You can turn on and off the display of any areas and rearrange the areas any way you want. Each area is explained below.

Working model

window

Toolbars

Database window

Toolkit bar

Status toolbar

Modeling Option toolbar

Modeling Input

toolbar

Using the Toolkit Bar

The toolkit bar provides you with all the tools you need to create a model, including the geometries, constraints, and motions. It divides the tools into subcategories to make it easier for you to find the tools.

To select a tool:

1. Click the tool subcategory, such as Body or Force.

The set of tools in that category appears.

2. Click the desired tool.

Using the Toolbars

RecurDyn provides a set of toolbars at the top to let you quickly perform operations on your model and change modes. These are the same operations that you can perform using the menus.

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Using the Database Window

You can view all the data and entities in your model using the Database window. In addition, you can:

View and change the properties of each entity.

Make constraints and forces inactive and reactivate them.

Change the display modes of individual bodies.

Change to the edit mode of subsystems, bodies, and profiles.

To view the entities in your model:

Click the + in front of an entity in the database window.

Using the Working Model Window

The working model window is where you build your model. You can use the tools to zoom and rotate your model and set the working plane on which you build your model.

Using the Modeling Option and Input Toolbars

The two modeling toolbars at the bottom of the window help you create your model:

The Modeling Option toolbar sets the options for the current operation.

Modeling Input toolbar lets you enter coordinates or a parametric point name and value, depending on the required input.

For example, if you are creating a cylinder, in the Modeling Option toolbar, you set the method for creating the cylinder (define two points or define two points and a radius). Then, you enter the values for the two points or the two points and a radius in the Modeling Input Command toolbar. The toolbars are shown below.

To use the toolbars together to create your model:

1. Select an entity to create, such as a cylinder.

2. From the Modeling Option Toolbar, select a creation method, such as Point, Point, Radius.

3. Enter the first point in the Modeling Input toolbar.

4. Press Enter or click (on the right of the toolbar).

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5. Enter the second point in the Modeling Input toolbar.

6. Press Enter or click .

Status Bar

The Status bar provides information about the state of your model

System Modes in RecurDyn

There are four modes in which you can work in RecurDyn:

Model-Editing – Work on the entire model. Lets you create objects in your model at the top level in the model hierarchy.

Subsystem-Editing – Work on the all of the entities in a subsystem. Lets you create objects in your model that belong to a logical subsystem in your model. A subsystem can contain a group of entities that are created using the process automation of a RecurDyn toolkit, such as a belt, chain, or track assembly.

Body-Editing – Edit a particular entity in your model, such as ground, a link, or force.

Profile-Editing – Change the properties associated with a particular entity in your model.

By default, RecurDyn is in model-editing mode. You switch between the modes depending on the operations that you want to perform. In this tutorial, you’ll switch to body-editing mode to edit the ground and then you will switch to the profile-editing mode as needed to create geometry.

You change to body- or property-editing:

In the Database window, right-click an entity, and from the menu that appears, click Edit.

In the working model window, double-click a subsystem, body, or profile geometry.

Click on one of the mode tools on the toolbar.

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Changing the Gravitational Force Direction In this tutorial, you will change the gravitational force of the –Z directions.

To change the gravitational force direction:

1. From the Settings menu, select Gravity.

2. Set Load Default Gravity to –Z.

3. Click Load or fill out the value and direction of the –Z to the values:

X: 0 Y: 0 Z: -9806.65

Changing the Working Plane You will now use the Working Plane tool on the toolbar to change the working plane so it is in the XZ plane of the inertia reference frame.

To change the working plane:

1. In the toolbar, click the combo box next to the Working Plane Change tool.

2. Select Change to XZ.

The Working Plane tool can only change the working plane about the inertial reference frame. If you want to change the working plane about another plane, see the next Tip.

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Tip: How to select the working plane You can set the working plane about any grid or the working plane itself.

To set the working plane about any grid:

1. From the View menu, point to Working Plane, and then select Setup.

The Working Plane Setup dialog box appears.

2. Click the Pl button.

3. Select the plane of a marker or flat face.

4. Click OK.

You can set the working plane and the grid settings in this dialog box.

To change a working plane about the selected working plane:

1. Click the combo box next to the Working Plane Change tool.

2. Select one of the working planes.

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Chapter

3 Creating Geometry

Task Objective In this chapter, you will create geometry to define the 3D slider crank, which consists of:

Grounded bracket

Crank

Connecting rod

Slider bodies

Grounded bracket

Crank

Connecting rod

Slider


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C R E A T I N G G E O M E T R Y 3 D S L I D E R C R A N K T U T O R I A L

Modeling the Grounded Bracket In this section, you create geometry to define the grounded bracket. You will create the bracket using two boxes, two cylinders, and two extrusions. This will also introduce you to the basics of using the toolkits to create geometry.

To change to body-editing mode for ground:

In the Body toolkit, click the Ground tool to enter the Body-Edit mode for the ground body of the model.

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To set the grid size to 10 in both the X and Z directions:

In the second row of the upper toolbar, set the grid size to 10 in both text boxes by placing the cursor in each text box, clicking the left mouse button, and typing 10, and then pressing the Enter key.

To create the box geometry:

1. In the Solid and Marker toolkit, click the Box tool.

2. Set the Modeling Option toolbar to Point, Point, Depth.

3. In the modeling window, click these points and input a depth for both boxes in the Modeling Input toolbar. (Note that you can also enter the points in the Modeling Input toolbar. For more on using the toolbars, see Using the Modeling Option and Input Toolbars in Chapter 2.)

Box1:

• Point1: 100, 0, -50

• Point2: -100, 0, 0

• Depth: 200

Box2:

• Point1: -150, 0, 200

• Point2: -100, 0, -50

• Depth: 200

The boxes you create should look like the following:

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To create the cylinder geometry:

Since you will create two cylinders at one time you will use the Auto Operation mode to automatically remain in the cylinder creation mode. The Auto Operation mode can be used with any input command and it can save a substantial amount of time when you are creating many entities of the same type.

1. Click on the Auto Operation tool to activate the Auto Operation input mode.

2. In the Solid and Marker toolkit, click the Cylinder tool.

3. Set the Modeling Option toolbar to Point, Point, Radius.

4. In the modeling window, click these points and input a depth for both cylinders in the Modeling Input toolbar:

Cylinder 1:

Point1: -100, 0, 170

Point2: -80, 0, 170

Radius: 20

Cylinder 2:

Point1: -80, 0, 170

Point2: -40, 0, 170

Radius: 5

5. Click on the Auto Operation tool again to exit the Auto Operation input mode.

6. Click on the Escape (Esc) key to exit the Cylinder input tool.

The cylinders you created should look like the following:

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Tip: How to modify the geometry properties If you want to modify the parameters of geometry, you can modify them using the Property dialog box.

The following shows the properties for a box and a cylinder.

To create an extrusion:

1. From the toolbar, click the combo button next to the Working Plane tool and select Change to YZ to define the working plane as the YZ plane of inertia reference frame.

2. In the Profile toolkit, click the Profile tool.

3. To create 2-D line geometry for the extrusion profile, in the Profile toolkit, click 2D Line.

4. Create the profile using the points below. The profile that should result is shown in the figure below. You may find that inputting the values in the Modeling Input toolbar is the most efficient way to enter the values.

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Point X, Y

1 -100, 0

2 -100, -50

3 100, -50

4 100, 0

5 30, 0

6 30, -20

7 60, -20

8 60, -40

9 -60, -40

10 -60, -20

11 -30, -20

12 -30, 0

13 -100, 0

5. To finish the creation of the profile, right-click the working model window, and from the menu that appears, click Finish Operation.

6. You can edit the 2-D line by using the Property dialog box for the profile just created to correct any errors.

7. Exit the profile-creation mode (see the tip below).

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Tip: How to exit a mode There are two ways to exit a sub-mode:

Right-click the working model window, and from the menu that appears, click Exit.

From the Tool menu, click Exit.

To create the solid extrusion:

1. Define the working plane as the YZ plane. (Tip: Click the combo button next to the Working Plane tool and select Change to YZ.)

2. In the Profile toolkit, click the Extrude tool.

3. In the working window, click the profile line that you just created. It will be a vertical line at an x value of 0.

4. Click the point on ground or input a distance in the Modeling Input toolbar:

Point1: 0, 250, 0

or

Distance: 250

The bracket should now look like the figure on the next page. You may need to rotate it to see it (in the working model window, type r and hold down the left mouse button to rotate).

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To move the extrusion geometry to the right:

1. Define the working plane as the XZ plane.

2. On the toolbar, click the Object Control tool.

3. Select the Extrusion geometry.

4. Enter the Offset Value of 100.

5. Click +X button.

6. Close the Object Control dialog box (use the x in the upper right corner).

The extrusion geometry moves from here:

To here:

7. Exit the body-editing mode for the Ground body by right-clicking the working

model window and clicking Exit.

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Saving Your Model Take a moment to save the work you’ve done so far.

To save your model:

1. From the File menu, click Save.

2. Enter the location and name for the file.

3. Select OK.

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Modeling the Crank Body Now you will create the crank.

To define the working plane:

Define the working plane as the YZ plane.

To create the crank body:

1. In the Body toolkit, click the Link tool.

2. Click these points:

Point1 [ 0, 0, 30 ]

Point2 [ 0, 0, 170 ]

Your link geometry should now look like the one shown below.

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To change the name of the body:

1. Right-click the working window over the model, point to Properties, point to Bodies, and and then click Body1.

The Properties dialog box appears.

2. Click the General tab.

3. Change the body name from Body1 to Crank.

4. Click OK.

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Tip: How to use the Database window to access properties You can use the Database window to access the properties.

To use the Database window:

1. In the Database window, right-click an object.

2. From menu that appears, click Property

Modifying the Link Geometry of the Crank

In this section, you’ll change the radius of the crank.

To modify the link geometry of the crank:

1. Change to Body-Editing Mode of the Crank body:

a. In the Database window, right-click Crank.

b. From the menu that appears, click Edit. The link is now the only geometry in the working model window.

2. While still in the body-editing mode of the Crank, display the Link1 geometry property dialog box:

a. In the Database window, right-click Link1.

b. From the menu that appears, click Property.

3. Modify the link Properties (by default the units are in mm):

First Radius: 20 Second Radius: 25 Depth: 20

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Creating Sphere (Ellipsoid) Geometry and Uniting it with the Link Geometry of the Crank

In this section, you’ll create ellipsoid geometry and use the Boolean unite command to unite it with the link geometry you created earlier.

To create the ellipsoid:

1. While still in the body-editing mode of the Crank, select Ellipsoid from the Solid and Marker toolkit.

2. Click on a point and enter a radius for the sphere:

Point: 0, 0, 30

Distance: 15

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To unite the ellipsoid and crank:

1. In the Boolean toolkit, click the Unite tool.

2. Select the Crank geometry and then the Ellipsoid geometry. (You can enter their names in the Modeling Input toolbar as well).

The crank geometry and the ellipsoid were listed separately in the Database window …

and now appear under a subcategory of Unite1.

Tip: How to work with Boolean operations A Boolean operation can work between two geometries only. The united geometry is displayed as Unite1 in the Database window.

You can select the entities in the working model window.

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Tip: How to undo a Boolean Unite Operation You can restore the united geometry to its previous state using the Delete Top Node only menu shown below. In this case, the top node would be the Unite1.

To delete the top node:

1. Right-click the node.

2. Click Delete Top Node only.

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Performing a Boolean Subtract Operation

In this section, you will create another ellipsoid geometry and subtract it from the crank geometry you created in the previous section to create a hole for locating the attachment point of the connecting rod.

To create the ellipsoid geometry and move it:

1.ge

While still editing the crank, in the Solid and Marker toolkit, create Ellipsoid ometry:

Point: 0, 0, 30

Radius: 15

2. Select Ellipsoid2.

3. Click the Object Control tool to open the Object Control dialog box.

4. In Offset Value, enter 5.

5. Click +X.

The Ellipsoid moves to the right 5 pixels as shown below.

6. Exit the Object Control dialog box (click the X in the upper right corner).

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7. In the Boolean toolkit, click the Subtract tool.

8. Select Unite1 and then Ellipsoid2.

RecurDyn subtracts the ellipsoid from the crank, as shown in the next figure. A database object of Unite1 now appears under a top node of Subtract1 in the Database window as also shown next.

Adding a Collar to the Crank

In this section, you’ll now create some cylinder geometry to define the collar of the Crank body.

To create a cylinder:

1. Define the working plane as the XZ plane of the inertia reference.

2. While still editing the crank, in the Solid and Marker toolkit, click the Cylinder tool.


4. Click these points and input the radius.

Point1: 10, 0, 170

Point2: 30, 0, 170

Radius: 20

The cylinder should appear as shown next.

5. Right-click the working window, and click Exit to exit the body editing mode of the crank.

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Moving the Crank Body

To move the crank body:

1. Select the Crank body.

2. On the toolbar, click the Object Control tool.

3. Using the Object Control dialog box, move the Link1 body 70 mm in the –X direction.

4. Exit the Object Control dialog box.

5. Change the color of the Crank body.

a. Right-click the Crank in the working model window.

b. In the Properties dialog box, select the Graphic Property tab.

c. Set Color to gray (second icon in the second row of the color palette).

d. Click OK.

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Saving Your Model Take a moment to save the work you’ve done so far.

To save your model:

From the File menu, click Save.

Creating the Connecting Rod Now you will create the connecting rod by creating a cylinder and two ellipsoids and then uniting them with Boolean operations.

To create the cylinder:

1. In the Body toolkit, click the Cylinder tool.


3. Create the cylinder body:

Point1: -60, 0, 30

Point2: 290, 0, 50

Radius: 7

4. Change the name of the Cylinder to Connecting_Rod. (Tip: To access the Properties dialog box, right-click the cylinder body name, Body1, click Properties, and then click the General tab.)

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5. Enter Body-Editing mode of the Connecting_Rod, (Tip: In the database window, right-click Connecting_Rod, and click Edit.)

Only the connecting rod appears in the working model window.

6. In the Solid and Marker toolkit, click Ellipsoid and create the ellipsoid geometry:

Point: -60, 0, 30

Distance: 13

7. Create another Ellipsoid geometry:

Point: 290, 0, 50

Distance: 13

8. Unite all the geometry using the Unite tool in the Boolean toolkit.

The rod should look like the following: (Tip: Set the rendering mode to Shaded. From the View menu, point to Rendering Mode, and click Shade.)

9. Exit Body-Editing mode. (Tip: Right-click the working model window, and click Exit.)

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Modeling the Slider To model the Slider body, you will create a base box, an upper center box, and link geometry, and then subtract a sphere from the link to locate the attachment location for the connecting rod.

To create the box:

1. Change the working plane to YZ plane.

2. In the Body toolkit, click Box.


4. Create the box geometry:

Point1: [ 0, -60, -20]

Point2: [ 0, 60, -40]

Depth: 100

The box should appear as shown below. You may need to rotate the model to see the box (type r in the working model window) and you may need to set the rendering mode back to Wireframe with Silhouettes if you changed it earlier to Shade (from the View menu, point to Rendering Mode, and click Wireframe with Silhouettes).

5. Change the body name to Slider.

To add a box to the Slider body:

1. Enter the Body-Editing Mode of Slider.

2. In the Solid and Marker toolkit, click the Box tool.


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4. Create box geometry:

Point 1: 0, -30, 20

Point2: 0, 30, -20

Depth: 100

To add link geometry to the Slider body:

1. In the Solid and Marker toolkit, click the Link tool.

2. Set the Model Option toolbar to Point, Point, Depth.

3. Create the Link1 geometry:

Point 1: 0, 0, 50

Point2: 0, 0, -10

Depth: 20

The link should appear as shown next.

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4. Modify the link geometry (Tip: In the Database window, right-click Link1, point to Property, and then click the Link tab):

First Radius: 20

Second Radius: 25

To create ellipsoid geometry:

1. In the Solid and Marker toolkit, click the Ellipsoid tool.

2. Create an Ellipsoid geometry:

Point: 0, 0, 50

Distance: 15

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To unite the two geometries:

1. From the Boolean toolkit, click the Unite tool.

2. Select the Link1 and Ellipsoid geometries.

The geometry changes from:

To create an ellipsoid and subtract it from the Slider:

1. Define the working plane as the XZ plane.

3. In the Solid and Marker toolkit, click the Ellipsoid tool.

4. Create an Ellipsoid geometry:

Point: 0, 0, 50

Distance: 15

5. From the toolbar, click the Object Control tool, and move the Ellipsoid2 geometry to 5 mm with respect to +X axis. Close the Object Control tool.

6. From the Boolean toolkit, click the Subtract tool.

7. Select the Unite1 and Ellipsoid2 geometries.

To rotate the subtracted geometry:

1. Define the working plane as the YZ plane.

2. Select Subtract1.

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3. From the toolbar, click the Object Control tool, and click the Rotate tab.

4. Rotate the Subtract1 geometry 180o about the Z axis as shown below.

To fillet the edges of the upper box geometry:

1. In the Local toolkit, click the Fillet tool.

2. Select the upper Box.

The Fillet Operation dialog box appears.

3. Click Add Edge.

4. Click the edges that make up the top and sides of the box, not the bottom, as shown in the picture to the right. The edges you select appear in the Fillet Operation dialog box, as shown below.

5. Change the radius for each edge to 10, as shown in the Fillet Operation dialog box above.

6. Click OK.

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The geometry changes as shown below.

7. Unite the geometries of Slider body. Otherwise the material in the link that intersects with the volumes of the two boxes would be counted twice in the mass property calculation.

8. Exit the Body-Editing Mode of the Slider body.

To move the Slider body:

1. Change the working plane to the XZ plane.

2. Select the Slider body.

3. Change the color of the Slider:

a. In the Database window, right-click Slider.

b. Click Property.

c. Click the Graphic Property tab.

d. Change the color of the Slider body to blue.

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4. From the toolbar, click the Object Control tool, and move the Slider body 300 mm in the +X direction:

Saving Your Model Before going to the next chapter and adding joints to your model, take a moment to save the work you’ve done so far.

To save your model:


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Chapter

4 Creating Joints

Task Objective In this chapter, you will create several joints. You will create a:

Revolute joint between the Grounded Bracket and the Crank

Spherical joint between the Crank and the Connecting Rod

Spherical joint between the Connecting Rod and the Slider

Translational joint between the Slider and the Grounded Bracket

You will also define the input motion of the crank.


43

Creating Joints 3D Slider Crank Tutorial

Creating the Revolute Joint In this section, you’ll create the revolute joint between the grounded bracket and the crank.

To create the revolute joint:

1. In the Joint toolkit, click the Revolute tool.

2. In the Modeling Option toolbar, set the creation method to Point, Direction.

3. Click two points:

Point1 [ -70, 0, 170 ] Point1 becomes the center point of the joint.

Point2 [ -20, 0, 170 ] Point2 defines the rotational axis(z-axis) of the revolute joint with respect to the point1.

Tip: Modeling Options When you set the modeling option to Point, Direction, RecurDyn defines the base and action bodies automatically. The name of the connected bodies can be seen at the right of the cursor position.

If you want to specify the base body and action body manually, you can specify the bodies by changing the modeling option to Body, Body, Point, Direction.

Direction Point Center Point

Base Body

Action Body Center Point

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Adjusting the Icon and Marker Size You are now going to change the icon and marker size to 20 pixels so you can view the model better.

To change the icon and marker size:

1. Display the Icon/Marker dialog box by doing one of the following:

In the toolbar, click the Icon Size tool.

From the View menu, click Icon Size.

The Icon/Marker Size dialog box appears.

2. Set Icon Size and Marker Size to 20.

3. Click OK.

The graphics display changes those shown in the earlier figure to the one shown below.

Creating Two Spherical Joints Now you will create the two spherical joints that connect between the crank and the connecting rod and between the connecting rod and the slider

To create spherical joints:

1. In the Joint toolkit, click the Spherical Joint tool.

2. Set the Motion Option toolbar to Body, Body, Point.

3. Click two bodies and one point:

Body: Crank and Connecting Rod

Point: -60, 0, 30 Point becomes the center point of the joint.

45


4. In the Joint toolkit, click the Spherical tool.

5. Set the Motion Option toolbar to Body, Body, Point.

6. Click two bodies and one point:

Body: Connecting Rod and Slider

Point2: 290, 0, 50

46


Creating the Translational Joint Now you will create the translational joint between the slider and the grounded bracket.

To create the translational joint:

1. In the Joint toolkit, click the Translational tool.

2. Set the Modeling Option toolbar to Body, Body, Point, Direction.

3. Click two bodies and two points:

Select Bodies: Ground (becomes the base body for the joint) and Slider (becomes the action body for the joint)

Point1: 300, 0, -20 Point1 becomes center point of the joint.

Point2: 400, 0, -20 Point2 becomes the direction point of the joint. It defines the translational axis with respect to point1.

47


Creating a Motion on the Revolute Joint Now you will define a motion on the revolute joint you just created.

To define a motion:

1. Display the property dialog box of RevJoint1. (Tip: Right-click RevJoint1 in the Database window, and click Property).

2. Click the Joint tab.

3. Check the Include Motion box.

4. Click Motion.

The Motion dialog box appears. Pull down on the second pull-down menu and set the motion type to Velocity (time).

48


5. Click EL.

The Expression List dialog box appears.

For more information on using Exprssion List, see the next Tip.

6. Click Create.

The Expression dialog box appears.

7. Enter the following motion expression in the upper box of the Expression dialog box.

2*PI

8. In the Expression dialog box, click OK.

49


The new expression you created appears in the Expression List dialog box.

9. In the Expression List dialog box, click OK.

10. In the Motion dialog box, click OK.

11. In the Joint dialog box, click OK.

Tip: More about the Expression List Box The Expression List dialog box stores all expressions used in the model. If you create a motion expression in the Joint dialog box, RecurDyn stores the motion expression in the Expression List dialog box.

You can use an expression in the Expression List dialog box with other entities.

50

Chapter

5 Performing Analysis

Task Objective In this chapter, you’ll run a simulation of the model you just created. The simulation


51

PERFORMING ANALYSIS 3D SLIDER CRANK TUTORIAL

Performing Dynamic/Kinematic Analysis In this section, you will run a dynamic/kinematic analysis to view the effect of forces and motion on the model you just created.

To perform a dynamic/kinematic analysis:

1. In the toolbar, click the combo box next to the Simulate tool, and then click Dynamic/Kinematic.

The Dynamic/Kinematic dialog box appears.

2. Define the end time of the simulation and the number of steps:

End Time: 1

Step: 200

Step Multiplier Step Factor: 5

3. Click Simulate.

RecurDyn calculates the motions and forces acting on the slider crank.

Tip: Meaning of Options in Simulate dialog box Here is a quick list of the most commonly used options in the Dynamic/Kinematic dialog box:

End Time: Defines the length of the Simulation Time.

Step: Defines the number of animation frames to store throughout the simulation time.

Plot Multiplier Step Factor: Defines the number of data points that are saved for plotting. The number of the plot data points that are stored is defined as:

Step * Plot Multiplier Step Factor

52

Chapter

6 Working with Animations

Task Objective In this chapter, you will learn how to animate the motion of the model and how to create an AVI file of the animation for use in presentations. You will also learn how to trace the paths of points on the moving bodies.


53

PLAYING ANIMATIONS 3D SLIDER CRANK TUTORIAL

About the Animation Toolbar You can animate your model while modeling or through the RecurDyn/Plot window. When you work with animations in RecurDyn/Plot you can play the animations as you display the plots to more completely analyze the data. The animation toolbar in RecurDyn/Plot is shown below. Each of its tools are explained in the table below.

The tool Does the following:

Go to the first frame.

Go back one frame.

Play/pause

Fast forward

Go forward one frame

Go to last frame.

Reverse Play/Pause

Fast Reverse Play/Pause

Stop

Record

Select camera

Animation control configuration

Playing Animations In RecurDyn/Plot, in the Animation tool bar, click the Play button.

54


Saving the Animation Data as an AVI File Now you will save the animation you just viewed as an AVI file so you could post it to the Web or play it in a PowerPoint presentation.

To save an animation as an AVI file:

1. In the Animation toolbar, click the Record tool.

The Create AVI file dialog box appears.

2. Define the size of the image in the AVI file by clicking on the combo box for the ovie Resolution field and selecting 600 x 800.

3.

ot saves the animation and displays a message when it is complete.

4.

g box, click Codec.

You can pick the compression scheme that

upon

le to play back the AVI file.

6.

M

Click Start.

RecurDyn/Pl

Click OK.

5. In the Create AVI file dialo

The Video Compression dialog box appears.

will be used to keep your AVI file at a reasonable size. The image quality, AVI file size and playback speed can all depend the compression scheme that you select. If you move the AVI file to another computer, that computer must support the selected compression scheme or the user will not be ab

Click on the combo box under Compressor and select Microsoft Video 1.

7. Click OK to return to the Create AVI file dialog box.

55


8. Click Save.

The File Save dialog box appears.

9. e file name and location for the AVI file.

10. Click Save.

o exit the Create AVI file dialog box.

racing the Paths of Points on the Moving Bodies ies was es to

g

nu, click the Marker Trace command.

times to create three lines in

3. Each line will have a marker button. Click on the Marker button for the

In the File Save dialog box, enter th

11. Click Close t

TIn the animation you saw that the motion of the crank, connection rod and slider bodsimple but different. Now you will trace out the path of a point on each of these bodibetter understand their motion. The point on each body will be defined by a marker. A marker is a coordinate system. It has an origin and an orientation. You will use some existinmarkers to trace some paths.

To trace the path of a point:

1. In the Post me

The Marker Trace dialog box appears.

2. Click the Add button three

the dialog box.

first line. The Navigation Target boxwill appear in the upper right of the Working Model Window.

56


4. Expand the Crank, Connecting Rod, and Slider Body names in the Database window. Expand the Markers headings for the Crank, Connecting Rod, and Slider Bodies. The Database Window should appear as shown on the right.

5. Select the Marker2 name under the Crank body and drag it to the Navigation Target Window. You should see the name Crank.Marker2 appear in the first row of the Trace Marker column.

6. Click on the Marker button for the second line.

7. Select the CM name under the Connecting_Rod body and drag it to the Navigation Target Window. You should see the name Connecting_Rod.CM appear in the second row of the Trace Marker column.

8. Click on the Marker button for the third line.

9. Select the Marker1 name under the Slider body and drag it to the Navigation Target Window. You should see the name Slider.Marker1 appear in the third row of the Trace Marker column.

10. Set the Width in all three rows to 3.

11. Set the Color in the first row to light grey by clicking on the C button and selecting the color in the second row and the second column of the palette.

12. Set the Color in the second row to cyan by clicking on the C button and selecting the cyan cell.

13. Set the Color in the third row to red by clicking on the C button and selecting the red cell. The Marker Trace dialog box should appear as in the figure.

14. Click OK to close the Marker Trace dialog box.

15. Play the animation again by clicking on the play button. You should see the three traces as shown in the figure.

57


The traces suggest the type of motion that each body is experiencing.

• The trace of the slider is the red line, suggesting motion in a single degree of freedom.

• The trace of the crank is a circle, suggesting a rotational motion with translations in two directions.

• The trace of the connecting rod is a slanted circle, suggesting that the connecting rod is undergoing both a rotational motion and a translational motion. The CM marker in the Connecting Rod is translating in all three degrees of freedom.

58


Tip How to use the Animation control configuration There are several configuration settings for animations that you can set when you select the Animation Configuration tool on the Animation toolbar:

Start Frame and End Frame: Defines the start frame and the end frame of an animation.

Frame Step: Increment frame of an animation.

Repeat: Defines the number of times to replay the animation.

Display Markers during Animation: If you check this option, you can see the markers during an animation.

59


60

Chapter

7 Plotting

Task Objective In this chapter, you will plot the analysis data that RecurDyn calculated in the dynamic/kinematic simulation you ran in the previous chapter. You will plot the motion of the slider body, using RecurDyn/Plot, a powerful post-processing tool, which is built into RecurDyn. It lets you plot and animate the results of simulations.


61

Plotting 3D Slider Crank Tutorial

Creating a Plot In this section, you’ll start RecurDyn/Plot and view a plot of the motion of the slider.

To start RecurDyn/Plot and plot the motion of the slider body:

1. In the toolbar, click the Plot Result tool.

The Plotting window appears with all the tools and data you need.

Animation tools

2. In the Database window, expand the Bodies heading, expand the Crank heading

3. Right-click on Pos_TX. Pos_TX is an abbreviation for “Position in Translation in the X direction.”

4. Select Draw from the pop-up menu that appears.

5. Now double-click on Pos_TY and Pos_TZ. You can see that double-clicking has the same effect as Steps 3 and 4. The plot should appear as in the figure.

Tabs for switching between plots and window s

Plotting window

Database window now contains output data from simulations

62


Note that the plot gives us the same feedback as the Trace Curve for the Crank body (presented in the previous chapter), which is that the motion of the Crank included translations in two directions. There is no translation in the Z direction.

Plotting in Multiple Panes In this section, you’ll learn how to use multiple panes in the Plotting Window to understand your model behavior more completely.

To switch the Plotting Window to display multiple panes:

1. In the toolbar, click the Show All Panes tool. You should now see four plotting areas within the Plot Window.

2. Set the upper-right pane to be the active pane by clicking on any point within it.

3. In the Database window, expand the Connecting_Rod heading under the Bodies heading

4. Double-click on Pos_TX, then Pos_TY, then Pos_TZ as you did with the previous plot.

5. Set the lower-left pane to be the active pane by clicking on any point within it.

6. In the Database window, expand the Slider heading under the Bodies heading

7. Double-click on Pos_TX, then Pos_TY, then Pos_TZ as you did with the previous plot. The plot should appear as in the figure. The curves in the plot for the slider body show us that the body is moving in one translational degree of freedom. The curves in the plot for the connecting rod body show us that the body is moving in all three translational degree of freedom.

63


Loading an Animation In this section, you’ll load an animation into one of the pane in the Plotting Window in order to display a coordinated view of output values and the motion of the mechanical system. Note that an AVI file of the combined plots and animation can be created by following the same steps that were outlined in the previous chapter.

To load an animation in a pane of the Plotting Window:

1. Set the lower-right pane to be the active pane by clicking on any point within it.

2. In the toolbar, click the Load Animation tool. The following alert box appears:

3. Click Yes and the animation will be loaded in the lower-right pane.

4. Change to the XZ plane.

64


5. Type f to fit the model within the pane.

rotate the model into a better viewing position. Repeat the fit command as needed.

ilar to the figure shown on the cover of is tutorial.

7. ation by clicking the Play button.

-right panes while a vertical line dicated the location of the current output point in the three plots.

You’re understand the basics of creating a RecurDyn model and studying its motion.

6. Type r and drag the cursor in the pane to

The Plotting Window should appear to be simth

Play the anim

You should see the model animating in the lowerin

done! Congratulations. By working on through this tutorial, you now

65

Table of Contents

Getting Started ................................................................................................... 5 Objective.................................................................................................. 5 Audience.................................................................................................. 6 Prerequisites............................................................................................ 6 Procedures .............................................................................................. 6 Estimated Time to Complete ................................................................... 6

Setting Up Your Simulation Environment ........................................................... 7 Starting RecurDyn ................................................................................... 8 Importing the CAD Geometry .................................................................. 9 Adjusting the Icon and Marker Size ......................................................... 10 Saving the Model ..................................................................................... 12

Organizing the Geometry ................................................................................... 13 Task Objective......................................................................................... 13 Merging the Imported Geometry.............................................................. 14 Changing Body Properties....................................................................... 16 Creating a Second Propeller Blade ......................................................... 18 Translating and Rotating the New Blade ................................................. 19 Saving the Model ..................................................................................... 20

Creating Joints ................................................................................................... 21 Task Objective......................................................................................... 21 Attaching the Propeller Blades to the Propeller Hub with Revolute Joints22 Attaching the Propeller Hub to the Engine............................................... 23 Attaching the Engine to Ground with a Fixed Joint .................................. 23 Defining the Rotation of the Propeller ...................................................... 24 Saving the Model ..................................................................................... 26

Creating Forces.................................................................................................. 27 Task Objective......................................................................................... 27 Controlling the Translation of the Propeller.............................................. 28 Controlling the Location Rotation of the Propeller Blades........................ 29 Saving the Model ..................................................................................... 30

Performing Analysis ........................................................................................... 31 Task Objective......................................................................................... 31 Performing Dynamic/Kinematic Analysis ................................................. 32

３

Creating Scopes and Setting Force Display ....................................................... 33 Task Objective......................................................................................... 33 Creating Scopes of Revolute Joint Rotation ............................................ 34 Setting Display of Forces......................................................................... 35 Saving the Model ..................................................................................... 36

Performing a Design Study................................................................................. 37 Task Objective......................................................................................... 37 Adjusting the Stiffness and Damping of Rotational Springs..................... 38 Running a New Analysis.......................................................................... 39 Questions to Consider After Viewing the Results of the Design Study .... 40 Ideas for Further Exploration ................................................................... 41

Plotting the Results ............................................................................................ 43 Task Objective......................................................................................... 43 Creating a Plot ......................................................................................... 44

４

Chapter

1 Getting Started

Objective In this tutorial, you will learn how to:

Import geometry that was created using a CAD system

Organize the imported geometry into the bodies needed for the simulation

Define translational and rotational spring forces

Define scopes that display a model output within a floating window in the modeling environment

You will also practice skills that you learned in the previous tutorial, 3D Slider Crank:

Constraint modeling to connect the left and right blades with the propeller hub and to connect the propeller hub to the engine

Running a simulation, animating the model, and plotting the results

In all, you will:

Create a simple model of an aircraft engine with an attached propeller

Study the relationship between the motion of a point at the tip of the propeller and the motion of the drive shaft

Express model outputs in the form of plots and animations

5

GETTING STARTED ENGINE WITH PROPELLER TUTORIAL

Audience This tutorial is intended for new users of RecurDyn. All new tasks are explained carefully.

Prerequisites Users should first work through the 3D Slider Crank Tutorial or the equivalent. We assume that you have a basic knowledge of physics.



Simulation environment set up and geometry import

10

Organization geometry 10

Joint/motion creation 10

Force creation 10

Scope and force display creation 5

Design study 10

Analysis 5

Plotting/Animation 10

Total: 70


6

Chapter

2 Setting Up Your Simulation Environment

Task Objective You will begin by learning how to set up the simulation environment, including setting units, materials, gravity, and the working plane. In addition, you will learn how to import the CAD geometry that models the propeller blade, propeller hub, and engine housing.


7

SETTING UP SIMULATION ENVIRONMENT ENGINE WITH PROPELLER TUTORIAL



RecurDyn starts up and the New Model dialog box appears.

2. In the Model Name text box, enter the name of the new model as Engine_Propeller.

3. Set Gravity to –Z and leave the defaults for all the other options.

4. Click OK.

Tip: Allowed Characters for Entities You cannot use spaces or special characters in the model name or in any RecurDyn entity. You can use the underscore character to add spacing to improve the readability of the name.

8


Importing the CAD Geometry Now you will import the CAD geometry for the propeller blade, propeller hub, and engine housing. This is a typical way you would use RecurDyn. Create the modeling geometry in a CAD program and import the CAD geometry into RecurDyn for analysis.

To import the propeller blade geometry:

1. From the File menu, click Import.

2. Set Files of type to ParaSolid File (*.x_t,*.x_b …).

3. In the Basic Tutorials folder of the RecurDyn installation, select the file: prop_blade.x_t

The Output window appears indicating the success.

4. Click X to close the Output window.

5. Click Open.

Notice that the blade geometry appears in the working model window and the body names ImportBody1 and ImportBody2 appear in the Database window.

To see the model better, you may want to:

1. Zoom the image:

On the toolbar, click the Zoom tool.

2. Set the rendering to shaded:

From the View menu, point to Rendering Mode, and then click Shade.

To import the remaining geometry:

Follow the instructions above, but this time, select the file, prop_hub.x_t, from the Basics Tutorials folder of the RecurDyn installation. Notice the hub geometry appears in the working model window and the body names ImportBody3 and ImportBody4 appear in the Database window.

Follow the instructions above, but this time, select the file, engine.x_t, from the Basics Tutorials folder of the RecurDyn installation. Notice the engine geometry appears in the working model window and eight new body names appear in the Database window.

The working window should display the imported geometry as shown in the figure on the right.

9


Adjusting the Icon and Marker Size You are now going to change the icon and marker size to 20 pixels so the icons do not obstruct the view of the model.


1. Display the Icon/Marker dialog box by doing one of the following:



The Icon/Marker Size dialog box appears.


3. Click OK.

The graphics display changes from the one shown on the previous page to the one shown below.

10


Tip How to turn on/off the marker display In addition to changing the size of marker and other entity icons, you can turn off the display of the icons.

To turn on/off the marker display:

1. Display the Icon On/Off dialog box by doing one of the following:

In the toolbar, click the Icon On/Off tool.

From the View menu, click Icon On/Off.

The Icon On/Off dialog box appears.

2. Clear the selection of All Markers.

3. Click OK.

Marker Icon Display On Marker Icon Display Off

11


Saving the Model Take a moment to save your model before you continue with the next chapter.

1. From the File menu, click Save.

2. Enter a name and location for the file.

3. Click Save.

12

Chapter

3 Organizing the Geometry

Task Objective Often when you import CAD geometry, RecurDyn translates it into a number of bodies that actually move together and can be considered as a single body in RecurDyn. For example, in Chapter 1, when you imported the propeller blade, RecurDyn created two bodies and two additional bodies when you imported the propeller hub. The two bodies from the propeller blade correspond to the blade supports and blade surface. The two bodies from the propeller hub correspond to the hub itself and a shaft.

For this model, you want the two imported bodies of the propeller blade to move together as a single RecurDyn body, and the imported bodies that make up the propeller hub and the engine to move as one. In this chapter, you will merge the imported bodies together to develop a RecurDyn model that you can work with efficiently.


13

Organizing the Geometry Engine with Propeller Tutorial

Merging the Imported Geometry The table below shows the relationship between the bodies that you to work with in the RecurDyn model and the imported bodies. You will merge certain imported geometry to form the engine body and other imported geometry to form the propeller hub body. You do not need to merge the propeller blade because it corresponds to a single imported body. Each merged body has the combined mass properties of all of the solid geometry of the corresponding imported geometry.

Body Name Imported Geometry

Prop_Blade ImportBody1, ImportBody2

Prop_Hub ImportBody3, ImportBody4

Engine ImportBody5 NONE_4, ImportBody6, ImportBody7, ImportBody8, ImportBody9, ImportBody10, ImportBody11

Engine Body

Propeller Hub Body

Propeller Blade Body

To merge the engine geometry:

1. From the Tools menu, click Merge Body.

The Merge Body dialog box appears. All of the bodies in the Source Body list are selected.

2. Clear the selection of ImportBody1, ImportBody2, ImportBody3, and ImportBody4 because this imported geometry corresponds to the propeller blade and the propeller

Click the

hub. You do not want to include it in the merged engine body.

3.

ody, in the working model window, click ImportBody10 (the gray geometry at the back end of the Engine Body).

5.

B button.

4. To select the Target b

Click OK.

14


Notice that the number of markers is reduced because when the bodies were separate, they each had one marker defining the center of their mass. Now that they are merged,

efore Merge After Merge

To merge the propeller hub geometry:

Body.

:

ause these imported geometry corresponds to the propeller blade.

ed geometry corresponds to the merged engine geometry.

3. Click the B button.

ody, in the working window, click ImportBody3 (the propeller hub geometry).

5.

To r eller blade geometry:

ody.

port 10 because these bodies correspond to the propeller hub and the engine.

3.

there is only one body and one marker at the combined center of mass, as shown in the figure below.

B

1. From the Tools menu, click Merge

2. Clear the selection of the following geometry

ImportBody1 and ImportBody2 bec

ImportBody10 because this import

4. To select the Target b

Click OK.

me ge the prop

1. From the Tools menu, click Merge B

2. Clear the selection of ImportBody3 and Im Body

Click the B button.

15


4. To select the Target body, in the working window, click ImportBody2 (the propeller blade surface geometry).

5.

Changing Body Properties odies, as well as their color, so you can more

s and color:

In the Database window, right-click ImportBody2.

ImportBody2.

tab, and

4. ic Property tab, pull down on the color palette,

5.

he procedure in Steps 1 – 5, change the name of

_Hub

7. Steps 1 – 3 and 5, change the name

Click OK.

Now you will change the names of the three beasily identify them.

To change their name

1.

2. From the menu that appears, select Property.

A Properties dialog box appears for

3. Click the Generalchange the name of the body to Prop_Blade1.

Click the Graph

and select yellow.

Click OK.

6. Following t

body ImportBody3 to Propand change its color to green.

Following the procedure in

of body ImportBody10 to Engine. Do not change its color.

16


The list of bodies in the database window appears as shown below:

Tip: How to display the Property dialog box for a body or icon

There are two methods to open the Property dialog box for a body: from the working model window or from the Database window.

To display the Property dialog box from the working model window:

1. In the working model window, right-click the body geometry.

2. From the menu that appears, click the following:

If there is a single entity at the cursor location, click Property.

If there are two or more entities near where you selected, then a tree structure of the entities appears to the right of the Properties entry. Navigate the tree structure and click the entity name to display its property dialog box.

To display the Property dialog box from the Database window:

1. In the Database window, right-click an entity.

2. From the menu that appears, click Property.

17


Creating a Second Propeller Blade Now you will create a second propeller blade by copying the first blade.

To create a second propeller:

1. In the toolbar, click the combo box next to the Working Plane Change tool.

2. Click Change to XY.

3. In the working model window, select Prop_Blade1. Tip: You can also place the cursor over the Prop_Blade1 name in the Database window and click.

Now you can copy and paste the blade to create the second propeller blade. RecurDyn is a Windows application that supports several methods for copying and pasting.

4. To copy the blade:

Type Ctrl+C on the keyboard.

On the toolbar, click the Copy tool.

From the Edit menu, click Copy.

In the working window, right-click and from the menu that appears, click Copy.

5. To paste the propeller, use the same techniques you used for copy

(Ctrl+V, click the Paste tool, or use the same menus as explained above).

You should see the new propeller blade as shown in the figure below. Notice that in the Database window RecurDyn prepends C1_ to the name of the original body to form the

name of the new body.

Original blade body New

blade body

18


Tip w to control the offset of pasted entities : HoNote that RecurDyn offsets the new body one grid distance down and to the right of the

gs menu, click Program Settings.

working plane. You can turn this option off.

To turn off the offset:

1. From the Settin

2. Clear the selection of Shift When Pasting.

3. Click OK.

ranslating and Rotating the New Blade side of the engine axle

:

ck the Object Control tool to display the Object Control Dialog Box. The Translate tab is active.

2. Be sure the C1_Prop_Blade1 body (the new propeller) is selected.

TYou need to translate and rotate the new blade so it is on the oppositefrom the original blade.

To translate the blade

1. On the toolbar, cli

3. Click the –X button.

4. Click the +Y button.

19


To rotate the blade:

1. Click the Rotate tab in the Object Control dialog box.

2. Change Degree to 180.

In this case, you will rotate the blade about the Z-axis of the global coordinate system (the default for the Reference Frame text box). If you need to rotate an object about an axis in a different reference frame, then click the M button and select the marker of interest.

3. Click the Z Rotation tool to rotate the blade 180 degrees.

Your model should appear as shown in the figure below.

4. Close the Object Control dialog box (click the X in the upper right corner).

5. Display the Properties dialog box for the new blade C1_Prop_Blade1 and rename it to Prop_Blade2.

Saving the Model Take a moment to save your model before you continue with the next chapter. (Tip: From the File menu, click Save.)

20

Chapter

4 Creating Joints

Task Objective In this chapter, you will create several joints. You will create:

Revolute joints to attach the propeller blades to the propeller

Cylindrical joint to attach the Prop_Hub to the engine

Fixed joint to fix the engine to ground

You will also define the rotation of the propeller.


21

CREATING JOINTS ENGINE WITH PROPELLER TUTORIAL

Attaching the Propeller Blades to the Propeller Hub with Revolute Joints In this section, you will use revolute joints to attach the propeller blades to the propeller hub. You will first set the working plane and adjust the grid size. A grid size of 10 in each direction will make it convenient to use the grid to locate some of the joints that you will define.

To set the working plane:

1. Set the working plane to the YZ Plane.

2. Change working plane to the left view (Change to Left) of the current plane.

To change the grid size:

In the toolbar, set the grid size to:

Height: 10

Width: 10 To attach Prop_Blade1 to the propeller hub:

1. In the Joint toolkit, click the Revolute Joint tool.

2. Set the Modeling Option toolbar to the creation method: Body, Body, Point

3. Click the Prop_Hub geometry.

4. Click the Prop_Blade1 geometry (on the right).

5. In the Modeling Input toolbar, enter the point -5, -31, 6. To attach Prop_Blade2 to the propeller hub:



3. Click the Prop_Hub geometry

4. Click the Prop_Blade2 geometry (on the left).

5. In the Modeling Input toolbar, enter the point -5, 31, 6.

You should see the joint icons as shown in the figure below.

22


Attaching the Propeller Hub to the Engine To attach the Prop_Hub body to the engine body with a cylindrical joint:

1. In the Joint toolkit, click the Cylindrical Joint tool.

2. Set the Modeling Option toolbar to the creation method: Body, Body, Point, Direction

3. Click the Engine geometry.

4. Click the Prop_Hub geometry.

5. Click the point 0, 0, -40 in the working window or enter 0, 0, -40 in the Modeling Input toolbar.

6. To set the direction, click the Z-axis of the inertia reference frame (the yellow arrow pointing up in the middle of the propeller hub).

Z-axis of the inertia reference frame

Attaching the Engine to Ground with a Fixed Joint To attach the engine body to ground with a fixed joint:

1. In the Joint toolkit, click the Fixed Joint tool.


3. To select ground, click anywhere in the working model window where there is no geometry.


5. Click the point 0, 0, -120 in the working model window or enter 0, 0, -120 in the Modeling Input toolbar.

23


You should see the joint icons as shown in the figure below.

Defining the Rotation of the Propeller You will now define a constant acceleration of the propeller that begins 0.1 seconds after the simulation starts.

To define the rotation of the propeller:

1. Display the Properties dialog box of the Cylindrical Joint.

2. Check Include Rotational Motion.

3. Click Rotational Motion.

The Motion dialog box appears.

4. Set the menu labeled Displacement (time) to Acceleration (time).

24


5. Click EL.

The Expression List dialog box appears.

6. Click Create.

The Expression dialog box appears.

7. To define a rotational acceleration of 10π radians/sec2 after 0.1 seconds of simulation time, enter the following expression in the large text box:

IF(TIME-0.1: 0, 0, 10*PI)

8. Click OK to exit the Expression dialog box.

9. Click OK to exit the Expression List dialog box.

10. Click OK to exit the Motion dialog box

11. Click OK to exit the Cylinder Joint Property dialog box.

25



26

Chapter

5 Creating Forces

Task Objective In this chapter, you will learn to create forces controlling the translation of the propeller and the local rotation of the propeller blades.


27

CREATING FORCES ENGINE WITH PROPELLER TUTORIAL

Controlling the Translation of the Propeller To create a translational spring force between the Prop_Hub and the engine:

1. In the Force toolkit, click the Spring tool.

2. Set the Modeling Option toolbar to the creation method: Body, Body, Point, Point


4. Click the Propeller Hub geometry.

5. Click the point 0, 0, -80 in the working model window or enter the point 0, 0, -80 in the Modeling Input toolbar.

6. Click the point 0, 0, -40 in the working model window or enter the point 0, 0, -40 in the Modeling Input toolbar.

28


Controlling the Local Rotation of the Propeller Blades To control the rotation of the propeller blades, you will create two rotational springs.

To create a coil (rotational) spring between Prop_Hub and Prop_Blade1:

1. In the Force toolkit, click the Rotational Spring tool.

2. Click the Revolute Joint (RevJoint1) at Prop_Blade1 (on the right).

Revolute joint to select

To create a coil (rotational) spring between Prop_Hub and Prop_Blade2


2. Click the Revolute Joint (RevJoint2) at Prop_Blade2 (on the left).

Revolute joint to select

You should see the new force icons as shown in the next figure, as well as new joint and force entries in the Database window.

29



30

Chapter

6 Performing Analysis

Task Objective In this chapter, you will run a simulation of the model you just created. You will rerun the simulation several more time later in the tutorial as you experiment with some changes to some of the model parameters.


31

PERFORMING ANALYSIS ENGINE WITH PROPELLER TUTORIAL

Performing Dynamic/Kinematic Analysis You will run a dynamic/kinematic analysis to view the effect of forces and motion on the model you just created.


1. In the toolbar, click the combo box next to the Simulate tool, and click Dynamic/Kinematic.

The Dynamic/Kinematic Analysis dialog box appears.


End Time: 2

Step: 200

Plot Multiplier Step Factor: 5

3. Click Simulate.

RecurDyn calculates the motions and forces acting on the slider crank. There will be 1000 plot outputs stored because the number of steps is 200 and the Plot Multiplier Step Factor is 5.

It displays the results in the Output window.

4. Click X to exit the Output window.

5. Animate the model using the Play button on the Animation toolbar. Refer to the 3D Crank Slider tutorial for more information on playing an animation.

6. Click Stop button to reset the model.

32

Chapter

7 Creating Scopes and Setting Force Display

Task Objective Before you run the simulation, you will create output data scopes that let you view analysis results in small plotting windows as you animate and plot the model. The scopes let you monitor angles, points, entities, and components of entities. In this tutorial, you will use scopes to monitor the local rotational motion of the blades. You will use the force display to monitor the forces at the revolute joints that attach the blades to the hub.


33

CREATING SCOPES AND SETTING FORCE DISPLAY ENGINE WITH PROPELLER TUTORIAL

Creating Scopes of Revolute Joint Rotation You will create two scopes that measure the:

Rotation at RevJoint1, which connects Prop_Blade1 to the Prop_Hub

Rotation at RevJoint2, which connects Prop_Blade2 to the Prop_Hub

To create a scope on a joint:

1. From the Post menu, point to Scope, and then click Entity.

The Scope Entity dialog box appears.

2. Click Et and then click the RevJoint1 icon, the icon for the revolute joint on the right side of the hub that connects Prop_Blade1 to the Prop_Hub body.

The name of the selected joint appears in the Entity Name text box.

The selection in the Component text box is Pos1_Relative. This is the rotational angle of the revolute joint and it is the output that you want. You do not need to change it.

3. Change the name of the scope to Scope_Rev_Ang1.

4. Click OK.

The scope plot appears with the angle rotation from the previous simulation. Note that the total rotation is small—only .3 degrees.

34


5. Now repeat Steps 1 - 5 with the changes needed to display the rotation of RevJoint2.

The second scope plot shows that the second revolute joint rotated the same amount as the first, but it has the opposite sign. The first blade rotates a small amount clockwise due to gravity, which is a negative rotation. The second blade rotates a small amount counter-clockwise due to gravity, which is a positive rotation.

Setting Display of Forces In this section, you will set up the display of the force in the translational spring along the propeller shaft during an animation.

To set up the force display of the translational spring, Spring1:

1. Display the Properties dialog box for Spring1.

The bottom item is the Force Display. Its default value is Inactive.

2. Set Force Display to Action.

3. Click OK.

You will not see any difference if your graphics are in the shaded mode. You need to to change them to the wireframe rendering to see the force vector.

4. Switch to the wireframe mode:

a. Right-click the working model window.

b. From the menu that appears, point to Rending Mode, and then click Wireframe.

5. Now use the Play button in the Animation toolbar to run the animation and look just above the coil spring on the propeller shaft for the force display.

35


You will see a force vector that spikes up a small amount and then quickly settles to a constant value (the weight of the propeller hub and blades).



36

Chapter

8 Performing a Design Study

Task Objective Your model with the default spring parameters behaves in a very stiff manner. The motion of the propellers seems to suggest a rigid connection rather than a flexible connection. In this chapter, you will learn how to use RecurDyn to study the effect of stiffness and damping on the dynamic response of a mechanical system.


37

PERFORMING DESIGN STUDY ENGINE WITH PROPELLER TUTORIAL

Adjusting the Stiffness and Damping of Rotational Springs You will use the two springs to study two factors:

With RotationalSpring1, you will reduce both the stiffness and damping by a factor of 100.

With RotationalSpring2, you will reduce the damping by an additional factor of 10.

To adjust the stiffness and damping of the rotational springs:

1. Display the Properties dialog box for RotationalSpring1.

2. Set the Stiffness to 100 and the Damping to 1.0 as shown above.

3. Click OK.

4. Display the Properties dialog box for RotationalSpring2.

5. Set the Stiffness to 100 and Damping to 0.1.

6. Click OK.

38


Running a New Analysis You are ready to run a simulation with the modified spring parameters. As you run the simulation, you will adjust a few simulation parameters to get the best answer for this model.

To run a new analysis with the modified spring parameters:



The Dynamic/Kinematic Analysis dialog box appears. Notice that the end time of the simulation and the number of steps have the values that you set in the first simulation. Therefore, you need to make no changes in the first tab.

2. Click the Parameter tab and set:

Maximum Time Step: 0.001

f

3. Click Simulate.

Numerical Damping: 0.1

The default values for Maximum Time Step and Numerical Damping work well for many practical problems that have many parts and high stiffness. For this model, you change them because:

Numerical Damping is applied at the system level and helps a model simulate smoothly when there is no damping defined for degrees ofreedom at the joints. In this model, you have damping defined for each degree of freedom and you are studying the effect of reducing the spring damping. In this case, it is a good practice to reduce the Numerical Damping from 1.0 to 0.1.

The Maximum Step Size is reduced because the numerical integrator in RecurDyn will take large steps with such a simple model that exhibits with smooth motion. A smaller maximum time step is appropriate because you want to capture the gradual decay of the blade motion.

39


The simulation will run in a few seconds. You will see some significant changes in the data shown on the two scopes. Both blades are moving through approximately

e

4. Click X to exit the the Output window.

5. o display the animation as explained in the beginning tutorial.


Questions to Consider After Viewing the Results of the De

es move through a larger displacement in the second simulation?

ulation?

s decrease in the later portions of the simulation?

5. How could you check for the accuracy of the solution?

20 degrees of initial rotation. There is much more oscillation in blade motion. Now is a good time to animate the model to observe the behavior that is suggested by thplots.

The Output window displays the results of the simulation.

Use the Animation play button in the Animation toolbar t

sign Study: Here are a few questions. The answers are provided later.

1. Why did the blad

2. Why did the blades oscillate more in the second sim

3. Why did Prop_Blade2 oscillate more than Prop_Blade1?

4. Why does the magnitude of the average rotation of the blade

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40


Ideas for Further Exploration:ou obtained interesting changes to the model results by changing the stiffness and damping

values of the rotational spring.

ess and damping in the coil (translational)

2. Think about the experimentation process. You may have a hard time deciding which

amping at the same time.

You can change the direction of the gravity vector by using the Gravity command in

Y

1. How could you change the values of stiffnspring?

change in which variable caused the changes in the output if you change the stiffness and the d

3. What change in response would you expect if you changed the gravity to act in the –Ydirection? Make the change and see if you were correct.

the Settings menu.

41


42

Chapter

9 Plotting the Results

Task Objective In this chapter, you will plot the analysis data that RecurDyn calculated in the dynamic/kinematic simulation you ran in the previous chapter. You will plot and work with the rotational output of the revolute joints, using the RecurDyn plotting tool. It lets you plot and animate the results of simulations.


43

P L O T T I N G R E S U L T S E N G I N E W I T H P R O P E L L E R T U T O R I A L

Creating a Plot In this section, you’ll start RecurDyn/Plot.

To start RecurDyn/Plot:

1. In the toolbar, click the Plot Result tool.

The Plotting window appears with all the tools and data you need.

Plotting window

Animation tools Database window now contains output data from simulations

Tabs for switching between plot and model windows

2. In the Database window, click the + in front of Joints and RevJoint1, and then double-click Pos1_Relative to display the rotation of Prob_Blade1 (same as the first scope).

3. Click RevJoint2, and then double-click Pos1_Relative to display the rotation of Prob_Blade2 (same as the second scope). The plot appears as shown next. It contains both curves of the two scopes in the same plot. It would be beneficial to be able to compare the two blade rotations, but the comparison is difficult because one curve has negative values and the other curve has positive values. You will use the analysis capability in the plotting tool to make this comparison easier.

44


4. From the Analysis menu, click Simple Math. The Simple Math dialog box appears.

5. Click the (curve1) * (ScaleFactor) tool.

6. Set Scaling Factor to -1.

7. Click Execute.

8. Click Close. A new curve appears on the plot that represents the absolute value of the Blade1 rotation.

9. Select the original Blade1 rotation curve (negative values) and you should see the curve become highlighted.

10. Press the Delete key on your keyboard to delete the curve. Click Yes when prompted to confirm the deletion of the curve.

11. In the toolbar, click the Fit tool to adjust the plot boundaries and display the plot as shown below.

45


46

１


３

Table of Contents

Getting Started...........................................................................5 Objective..........................................................................................5 Audience..........................................................................................6 Prerequisites....................................................................................6 Procedures ......................................................................................6 Estimated Time to Complete ...........................................................6

Setting Up Your Simulation Environment ..................................7 Task Objective.................................................................................7 Starting RecurDyn ...........................................................................8 Adjusting the Icon and Marker Size .................................................8

Creating Geometry ..................................................................11 Task Objective...............................................................................11 Creating the Guide Geometry........................................................12 Creating the Ball Geometry ...........................................................15 Saving the Model ...........................................................................16

Creating Forces .......................................................................17 Task Objective...............................................................................17 Defining the Compressed Spring...................................................18 Defining the Contact Between the Balls.........................................19 Defining Contact Between the Balls and Guides ...........................20 Saving the Model ...........................................................................22

Performing an Analysis and a Design Study ...........................23 Task Objective...............................................................................23 Performing Dynamic/Kinematic Analysis .......................................24 Performing a Design Study............................................................25 Animating the Results of a Trial .....................................................29 Ideas for Further Exploration .........................................................30

5

Getting Started

Objective The modeling and simulation of contact between bodies is an important topic in multibody dynamics. RecurDyn has powerful capabilities to define and simulate all types of contacts, from simple to complex and with body geometry created in RecurDyn, as well as geometry that is imported from CAD software. Consideration of contacts is needed to model designs that have interesting responses to model changes.

In this tutorial, you’ll act as a company developing a novel pinball machine that includes a higher level of vertical motion. One aspect of the model is that the ball goes up and down a curved ramp as it is propelled from its starting point. The purpose of the tutorial is to select the spring that can store sufficient energy to propel the ball over the vertical obstacle.

This tutorial provides the first exposure to contact modeling. You will learn how to:

• Create wireframe geometry.

• Define 2D contacts between bodies.

• Define a parametric value.

• Run a design study.

You will:

• Simulate a small portion of a pinball game, where balls contact each other and guides that act as boundaries.

• Study the relationship between the driving force of the ball launcher and the response of the system.

Chapter

1

P I N B A L L T U T O R I A L G E T T I N G S T A R T E D

6

Audience This tutorial is intended for new users of RecurDyn. All new tasks are explained carefully.

Prerequisites Users should first work through the 3D Crank-Slider Tutorial and the Engine with Propeller Tutorial, or the equivalent. We assume that you have a basic knowledge of physics.



Simulation environment set up 5

Geometry creation 5

Contact definition 10

Spring and parametric value creation 10

Set up of design study 10

Analysis 5

Animation 5

Plotting 10

Total: 60


7

Setting Up Your Simulation Environment

Task Objective Learn how to set up the simulation environment, including units, materials, gravity, and the working plane.


Chapter

2

P I N B A L L T U T O R I A L S E T T I N G E N V I R O N M E N T

8



RecurDyn starts and the New Model window appears.

2. Enter the name of the new model as Pinball.

3. Click OK.

Adjusting the Icon and Marker Size You are now going to change the icon and marker size to 10 pixels so you can view the model better.


1. Display the Icon/Marker window by doing one of the following:



The Icon/Marker Size window appears.


3. Click OK.


9

To set the grid size to 10 in both the X and Z directions:

In the second row of the upper toolbar, set the grid size to 10 in both text boxes by placing the cursor in each text box, clicking the left mouse button, typing 10, and then pressing the Enter key.


10

11

Creating Geometry You will use wireframe geometry to define the ball guides in this pinball model. You will define all of the guides on the ground body, and define several balls at the model level as individual bodies.

Task Objective Learn to create:

Line and arc geometry that will guide the motion of the balls.

Spherical geometry that represents the three balls in the model.


Chapter

3

P I N B A L L T U T O R I A L C R E T I N G G E O M E T R Y

12

Creating the Guide Geometry To create the straight guide geometry:

1. To enter Body Editing mode for the ground body, in the Body toolkit, click the Ground tool.

You know that RecurDyn is in Body Editing Mode for the Ground body because:

The title in the upper left corner of the working model window changes to Ground@Pinball.

• The top item in the database window is Ground.

2. Change the working plane to the XY Plane.

3. In the Curve and Surface toolkit, click the Outline tool.

4. Click the following points or enter the coordinates into the Modeling Input toolbar:

Point 1: 0, 0, 0

Point 2: 110, 0, 0

5. Right-click and then click Finish Operation (the top item in the menu that appears) to finish the definition of the outline.

6. Click the Outline tool. Enter the following points:

Point 1: 140, 30, 0

Point 2: 140, 60, 0

7. Right-click and then click Finish Operation.

8. Click the Outline tool. Enter the following points:

Point 1: 230, 30, 0

Point 2: 450, 30, 0

9. Right-click and then click Finish Operation.

The following appears in the working model window.


13

To create the arc guide geometry:

1. In the Curve and Surface toolkit, click the Arc tool.

2. Follow the directions given below, which are also summarized in the next figure.

Center Point: 110, 30, 0

Radius Point: 140, 30, 0

Direction: -Y (click at 140, 20, 0 or a grid point in that same direction such that the arrow points straight down.)

Angle: 90 (Carefully select the end of Outline 1 or enter 90 in the Modeling Input toolbar. Note that the angle displayed in the Working Model window will be shown in radians.)

3. Click the Arc tool. Enter the following:



Direction: +Y (click at 140, 70, 0)

Angle: 180 (you are forming a semi-circle)

Outline 1

Outline 2

Outline 3

Center Point

Radius Point

Direction

Angle


14




Direction: +Y (click at 120, 70, 0)

Angle: 180 (you are forming a semi-circle)




Direction: -Y (click at 200, 50, 0)

Angle: 90

The geometry appears as shown in the figure below:

6. Exit the Body Editing mode for Ground by clicking the Exit tool (note that the Exit tool is available on the upper toolbars and in the pop-up window that appears when you right-click in the working model window).

7. Save your model. (Tip: From the File menu, click Save.)


15

Creating the Ball Geometry To create the ball geometry:

1. In the Body toolkit, click the Ellipsoid tool. Enter the following:

Center: 10, 10, 0

Radius: 10, 20, 0 (or enter 10 in the Modeling Input toolbar)


Center: 40, 10, 0


3. In the Body toolkit, clck the Ellipsoid tool. Enter the following:

Center: 320, 40, 0


The three spheres that you just created are bodies that have the names of Body1, Body2, and Body3. You will change them to names that more helpful in identifying them.

To update the ball bodies:

1. Display the Properties window for Body1:

In the General tab, change Name to Ball_1.

Click OK.



Click OK.



Click OK.

You model appears as shown in the figure on the next page.


16


(Tip: From the File menu, click Save.)

Ball_3

Ball_2

Ball_1

17

Creating Forces The behavior of this model is driven by forces. A compressed spring drives Ball_1 into Ball_2. The continuing motion of the balls results from gravity forces, contacts between balls, and contacts between the balls and the geometry.

Task Objective Learn to create three types of force elements:

Compressed spring that will act on Ball_1

Sphere-to-sphere contacts between the balls

Circle-to-curve contacts between the balls and the geometry


Chapter

4

P I N B A L L T U T O R I A L C R E A T I N G F O R C E S

18

Defining the Compressed Spring You will create a spring force and adjust its properties to reflect that it is a compressed spring. As a result, Ball_1 will be pushed to the right when the simulation begins.

To create the spring:

1. In the Force toolkit, click the Spring tool.

2. Change the Input Mode from Point, Point to Body, Body, Point, Point.

3. Click in the background of the Working Model Window to select the Ground body to be the base body of the spring.

4. Click on the Ball_1 geometry to select Ball_1 to be the action body of the spring.

5. Click on the following locations in the Working Model Window:

Point1: -20, 10, 0

Point2: 10, 10, 0

To adjust the spring properties:

1. Display the Properties window for the spring, which will have the name of Spring1.

2. In the Spring tab, change:

Spring Coefficient to 20.

Damping Coefficient to 0.05

Free Length to 45.

The length as defined is 30 mm. By changing the Free Length to 45, you are indicating that the spring is compressed by 15 mm. Given the spring Coefficient of 20, a load of 300 N will be applied to the ball at the beginning of the simulation. Once the spring length increases to 45 mm, the force becomes zero.

3. Click OK.


19

Defining the Contact Between the Balls To create the contact between the balls:

1. In the Contact toolkit, click the Sphere To Sphere tool. Enter the following:

Sphere: click Ball_1


2. In the Contact toolkit, click the Sphere To Sphere tool. Enter the following:




20

To adjust the contact between the balls:

1. Display the Properties window for the first contact, which will have the name of SphereToSphere1.

2. In the Characteristics tab, change:


Damping Coefficient to 0.2.

Friction Coefficient to 0.1.

3. Click OK.

4. Make the same adjustment to the contact properties of SphereToSphere2.

Defining Contact Between the Balls and Guides The first ball (Ball_1) is constrained by the spring and will only contact the straight line as the left of the guide geometry. Therefore, the contact only needs to be defined for the one piece of geometry.

To create the contact between the first ball (Ball_1) and the guide geometry:

1. In the Contact toolkit, click the Circle To Curve tool. Enter the following:

Curve: click the line geometry under Ball 1


2. Display the Properties window for the contact, which will have the name of CircleToCurve1.


21

3. In the Properties window, do the following:

In the CircleToCurve tab, change its Normal Direction between Up and Down until the preview arrow is pointed up as shown in the figure below.

In the Characteristics tab, change:




4. Click OK to exit the contact Properties window.

The second ball (Ball_2) will contact all of the guide geometry. Therefore, you will use a different input mode for the contact to efficiently define all of the contacts.

To create the contact between the second ball (Ball_2) and the guide geometry:

1. In the Contact toolkit, click the Circle To Curve tool.

2. Change the Input Mode from Curve, Circle (Sphere) to Multicurve, Multicircle (sphere).

3. Enter the following:

MultiCurve: Click every piece of guide geometry

In the upper right corner of the working model window, click inside the Done1 box.

MultiCircle (Sphere): click Ball_2

In the upper right corner of the working model window, click inside the Done2 box.

5. Display the Properties window for each of the seven new contacts, which will have the names CircleToCurve2 through CircleToCurve8.


22

6. For each, do the following:

In the CircleToCurve tab, change its Normal Direction between Up and Down until the preview arrow is pointed up as shown in the figure below (the size and location of the some of the arrows are adjusted for clarity).

Click the Base Curve Segment button. In the window that appears, change the number of Curve Segments to 20. Click OK to exit this window.

In the Characteristics tab, change:




Click OK to exit the contact Properties window.

To create the contact between the third ball (Ball_3) and the Guide geometry:

1. In the Contact toolkit, click the Circle To Curve tool.

2. Change the Input Mode back to Curve, Circle (Sphere).

3. Enter the following:

Curve: click the line geometry under Ball_3


4. Display the Properties window for this contact and make the same adjustments as described for the first CircleToCurve contact.


23

Performing an Analysis and a Design Study

Task Objective In this chapter, you’ll run a simulation of the model you just created. You will rerun the simulation under a design study environment to decide how to select a spring that will provide the right energy to move the ball over the hump.


Chapter

5

P I N B A L L T U T O R I A L P E R F O R M I N G A N A L Y S I S / D E S I G N S T U D Y

24



1. In the toolbar, click the combo box next to the Simulate tool.

The Dynamic/Kinematic Analysis window appears.


End Time: 1

Step: 500


3. Click Simulate.

RecurDyn calculates the motions and forces in the balls, spring and contacts. There will be 2000 plot outputs stored because the Number of Steps is 500 and the Plot Multiplier Step Factor is 4.

4. Animate the model by using the Play button on the Animation toolbar. Refer to the 3D Crank Slider tutorial for more details on playing an animation.

Notice that Ball_1 (the ball that is attached to the spring) moves to the right and impacts Ball_2 just enough to push it to the right and have it climb a fraction of the height of the obstacle. You look in the spring catalog and you find that this spring is available in 1 mm increments from 40 mm through 70 mm. You want to try out different lengths of the spring but you don’t want to have run the various cases and keep track of the results manually.

You want to do an automated design study, which is explained next.


25

Performing a Design Study The steps to performing a design study for this model are:

1. Define the free length of the spring as a Parametric Value that can be adjusted during the design study.

2. Define a Design Variable from the Parametric Value, where you add information about the data boundaries. The range of the free length of the spring is from 45 to 60 mm.

3. Define a Performance Index. This is an outcome of interest for the design study. In this case, you will measure the maximum position of Ball_2 in the X direction. If the maximum position of Ball_2 is more than 170, then you know that it has passed the top of the vertical obstacle.

4. Set the Number of Trials for this design study, which is 16 (from 45 through 60 with steps of 1 mm).

5. Run the Design Study. Outputs will automatically be directed to different output files.

6. Review and plot the results from the design study.

7. Animate a particular trial.


26

To define a parametric value:

1. Display the Properties window for the spring (Spring1).

2. Next to the Free Length text box, click the Pv button.

3. When the Parametric Value List window appears, click the Add button.

Change the Name to Spring_Free_Length.

Set the Value to 45.

Click OK to exit the Parametric Value List window.

4. Click OK to exit the Spring1 Properties window. You will see that the name of the Parametric Value appears in the Free Length text box.

To define a design variable:

1. From the Analysis menu, select Design Study.

The Design Study window appears

2. In the Design Variables section of the Design Study window, click the Add button.

The Design Variable List window appears.

3. In the Design Variable List window, click the Create button.

The Design Variable window appears.

4. Do the following in the window:

Change Name to DV_Spring_Lo.

Click the Pv button and select the Spring_Free_Length of Parametric Value.

Click OK to exit the Parametric Value window.


27

5. In the Design Variable window:

Set Value Range to Absolute Min And Max Value.

Set Min Value to 45.

Set Max Value to 60.

Click OK to exit the Design Variable window.

6. Click OK to exit the Design Variable List window.

To define a performance Index:

1. Click the Add button in the Performance Indexes section of the Design Study window.

The Performance Index List window appears.

2. Click the Add button in the Performance Index List window.

Change the Name to Ball_2_Travel.

Set Type to Max Value.

Click the El button.

The Expression List window appears.

3. Click the Create button.

The Expression window appears.

4. Do the following in the window:

Change Name to Exp_Ball2_PosX.

In the Expression text box, enter DX(1).

In the Argument List section of the Expression window, click Add.

Expand the Ball_2 body entry in the Database window and then expand the Markers entry that appears under Ball_2.


28

Drag the name CM from the Markers entry under the Ball_2 body entry in the Database window to the blank text box in the Argument List section of the Expression window.

Click OK to exit the Expression window.

5. Click OK to exit the Expression List window.

6. Click OK to exit the Performance Index List window.

To set the number of trials:

In the Number of Levels text box in the Design Study window, type 16.

To run the design study:

In the Design Study window, click the Simulate button.

16 runs occur in the output window. When the runs are complete, the Design Study window reappears.

To review and plot results:

1. Click the Result Sheet button.

A list of the 16 runs appears:

The first column displays the value of the Free Length of the spring.

The second column displays the maximum X value of the center of Ball_2.

By inspection, you can see that Trials 1-9 did not make it over the vertical obstacle because the Ball_2_Travel Performance Index is less than 170. Trials 10-16 have an output that is greater than 170, which means that the ball made it over the vertical obstacle and continued to the right.

2. To plot the Ball_2_Travel Performance Index, under the Performance Indexes heading, click the box in front of Ball_2_Travel, and then click Plot.


29

The following plot appears when you click the Plot button:

3. Click the x in the upper right corner and to close the plot and click Close in the Result Sheet window.

4. Click OK to close the Design Study window.

Animating the Results of a Trial You’ll first take a look at Trial 10, which is the first trial where Ball_2 makes it over the vertical obstacle.

To animate the results of a particular trial:


2. Set Files of type to RecurDyn Animation Data File (*.rad).

3. Double-click Pinball_10.rad, which contains the animation results for Trial 10.

4. Animate the model using the Play button on the Animation toolbar.


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Ideas for Further Exploration

You can gain a good understanding of the behavior of the pinball model by looking at the animations of several of the trials. Here are few more things to consider:

The model used a low coefficient of friction (0.1). It represents the friction of a polished steel ball interacting with a smooth, dry surface. Low friction is a good assumption for the new pinball machine, but what about when the machine becomes old (dirty and some corrosion)?

How might the coefficient of friction change?

What could you do to study the effects of increased friction in this model?

Does increased friction require a stronger or weaker spring?

How might installation of the pinball machine affect its performance? (Think of a floor that is not level.) How could you change the modeling approach to make it easier to consider non-level installations?

Thanks for participating in this tutorial!

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Table of Contents

Getting Started...........................................................................5 Objective..........................................................................................5 Audience..........................................................................................6 Prerequisites....................................................................................6 Procedures ......................................................................................6

Setting Up Your Simulation Environment ..................................7 Task Objective.................................................................................7 Starting RecurDyn ...........................................................................8

Importing Geometry ...................................................................9 Task Objective.................................................................................9 Importing the CAD Geometry ........................................................10 Creating the Ball Geometry ...........................................................12

Defining Joints and Forces ......................................................15 Task Objective...............................................................................15 Attaching the Return Piping to Ground ..........................................16 Attaching the Container to Ground ................................................16 Defining the Rotational Spring .......................................................17

Defining 3D Contact.................................................................19 Task Objective...............................................................................19 Defining Contact between Ball_1 and the Return ..........................20 Defining Contact between Ball_2 and the Return ..........................21 Defining Contact between Ball_1 and Ball_2.................................21 Defining Contact between Ball_1 and the Container .....................21 Defining Contact between Ball_2 and the Container .....................22 Adjust Contact Surface Resolution of the Return ..........................22 Saving the Model ...........................................................................23

Analyzing and Reviewing the Model........................................25 Task Objective...............................................................................25

T A B L E O F C O N T E N T S P I N B A L L T U T O R I A L

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Performing Dynamic/Kinematic Analysis .......................................26 Reviewing the Results ...................................................................26 Preparing and Running a New Simulation .....................................27 Comparing the Results of the Two Simulations .............................28 Determining the Reference Load...................................................30 Ideas for Further Exploration .........................................................32

5

Getting Started

Objective The modeling and simulation of contact between bodies is an important topic in multibody dynamics. RecurDyn has powerful capabilities to define and simulate 3D contacts. The example in this tutorial is to model a bowling ball return system and the container that collects the balls.

In this tutorial, you learn how to work with 3D contacts with enough detail to be able to model sophisticated contacts on your own. For simple demonstrations, it may seem appealing to simply define complete body-to-body contact. Real models, however, are often too complex to simulate efficiently when every possible contact is considered. RecurDyn offers the powerful capability to select faces to create logical contact surfaces. When you define the contacts, you can then use the logical contact surfaces. The result is detailed contact modeling that is also efficient.

This tutorial provides an introduction to 3D contact modeling using imported geometry. You will learn how to:

• Create multi-face contact surfaces from imported geometry.

• Define 3D contacts between bodies.

• Adjust contact parameters to correctly represent the physical system.

• Determine a load case for use in structural analysis.

You will:

• Simulate the behavior of two bowling balls that travel through a return channel and drop into a contrainer.

• Study the load cases that the simulation results define for the container body.

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Audience This tutorial is intended for new users of RecurDyn who previously learned how to create geometry, joints, force entities, and 2D contacts. All new tasks are explained carefully.

Prerequisites Users should first work through the 3D Crank-Slider, Engine with Propeller, and Pinball (2D contact) tutorials, or the equivalent. We assume that you have a basic knowledge of physics.



Simulation environment set up 1

Geometry import 5

Joint and force definition 10

3D contact definition 5

Analysis and review 5

Contact parameter adjustment 10

Analysis and review 15

Total: 51


7

Setting Up Your Simulation Environment

Task Objective Learn how to set up the simulation environment.

Estimated Time to Complete 1 minute

Chapter

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1. On your Desktop, double-click the RecurDyn tool.

RecurDyn starts and the New Model window appears.

2. Enter the name of the new model as Ball_Return.

3. Click OK.

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Importing Geometry You will import solid geometry to define the ball channel and container in this model. You will define contact surfaces using the imported geometry.

Task Objective Learn to:

Import solid geometry in Parasolid format.

Create a contact surface from the imported geometry using the Face Surface tool.


Chapter

3

10

Importing the CAD Geometry Now you will import the CAD geometry for the piping system and the container. In this case, the geometry was modeled in the CAD system in the correct locations. You do not need to adjust the geometry position.

To import the ball return system geometry:


2. Set Files of type to ParaSolid File (*.x_t,*.x_b …).

3. In the Basic Tutorials folder of the RecurDyn installation, select the file: Return.x_t

4. Click Open.

The Output window appears and displays a message indicating the success of the import.

If the Output window is in Autohide mode, it collapses when you move the cursor outside of the window.

If the window is pinned open, the window stays open.

5. Click X in the upper right of the Output window to close it.

Tip: You can click the Pin tool, , to switch from the pinned mode to Autohide.

The geometry representing the ball return piping appears in the working model window and the body name ImportBody1 appears in the Database window.

To see the model better, you may want to:

1. To zoom the image, do one of the following:

On the toolbar, click the Zoom tool.

From the View menu, point to View Control, and then click Zoom.

Type the z key on the keyboard.

2. To set the rendering to shaded, do one of the following:

On the toolbar, click the Shade tool.

From the View menu, point to Rendering Mode, and then click Shade.

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3. To rotate the image, do one of the following:

On the toolbar, click the Rotate tool.

From the View menu, point to View Control, and then click Rotate.

Type the r key on the keyboard.

To import the Container geometry:

Follow the instructions above, but this time, select the file, Container.x_t, from the Basics Tutorials folder of the RecurDyn installation.

The geometry representing the container appears in the working model window (see the figure below) and the body name ImportBody2 appears in the Database window.

To set the names of both bodies:

1. Display the Properties dialog box for ImportBody1:

Select the General tab, and then change Name to Return.

Click OK to exit the Properties dialog box.

2. Display the Properties dialog box for ImportBody2:

Select the General tab, and then change Name to Container


To save:


12

Creating the Ball Geometry You will create the two bowling balls that are included in this simulation. This process is not simply the creation of the ball geometry, but also the setting up of the correct mass properties, initial conditions, and names. Ball_1 will be given an initial velocity of 2 m/sec to the left, which provides the energy the initiates the action in the simulation.

To create the ball geometry:


Center: 3000, 1000, 0

Radius: Enter 90 in the Modeling Input toolbar


Center: 700, 0, 0

Radius: Enter 90 in the Modeling Input toolbar

To update the ball bodies:

1. Display the Properties dialog box for Body1, the first ball you created:


In the Graphic Property tab, change Color to Red.

In the Body tab:

o Change Material Input Type to User Input.

o Change Mass to 10.

o Change Mass Moment of Inertia (Ixx, Iyy, Izz) to 70000.

o Click Initial Velocity.

In the window that appears, select X Translational Velocity and set the value of the velocity to -2000.

Click Close to exit the Body Initial Velocity dialog box.


13

2. Display the Properties dialog box for Body2:


In the Graphic Property tab, change Color to Red.

In the Body tab:

o Change Material Input Type to User Input.

o Change Mass to 10.

o Change Mass Moment of Inertia (Ixx, Iyy, Izz) to 70000.


Your model appears as shown in the figure below.

Save your model.

15

Defining Joints and Forces In this chapter, you will create all the necessary joints and forces.

Task Objective You will create:

A fixed joint to hold the ball return geometry in place.

A revolute joint to define the pivot point of the container.

A rotational spring to define the coil spring that controls the rotation of the container as the balls drop into it.


Chapter

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Attaching the Return Piping to Ground To set the working plane for the joint and force creation:

Set the working plane to the XY Plane.

To attach the Return piping to ground using a fixed joint:

1. In the Joint toolkit, click the Fixed Joint tool.

2. Set the Modeling Option toolbar to the creation method: Body, Body, Point.

3. To select ground, click anywhere in the working model window where there is no geometry.

4. Click the Return geometry.

5. Click the point 1600, 0, 0 in the working model window or enter 1600, 0, 0 in the Modeling Input toolbar.

Attaching the Container to Ground You will attach the Container to ground using a revolute joint. You will use the container geometry to locate the revolute joint.

To zoom in on the Container:

1. Use the Select Zoom to zoom in on the Container geometry. You can access Select Zoom by:

On the toolbar, click on the Select Zoom tool.

From the View menu, point to View Control, and click Select Zoom.

Type the s key on the keyboard.

2. Click just outside one corner of the Container, then continue to hold the mouse button down and drag to the other side of the container.

To attach Container to ground using a Revolute Joint:

You want to define the joint at the center of the post on the side of the container.


2. Zoom in on the container as shown in the figure below. Move the cursor over the inner circle of the fillet on the end of the post. When you see the crosshair move to the center of the post and you see the coordinates by the cursor readout to be -2600, -850, 1430, you should then click the left mouse button to create the revolute joint.

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3. If you have any difficulty locating the cursor such that the crosshair snaps to the center of the pin, you can use a different method to define the joint.

Pull down the menu in the lower left of the RecurDyn window to change the Modeling Option to Body, Body, Point as shown below.

Select Ground by picking anywhere in the graphics window where there

is no body geometry.

Select the Container by picking on its geometry.

Enter the coordinates of the joint center, -2600, -85, 1430, directly into the modeling command input file in the bottom center of the window as shown in the figure above.

Defining the Rotational Spring You will create a rotational spring that will control the rotation of the container.

To create the rotational spring:


2. Click the icon of the revolute joint that you just created (RevJoint1).

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Defining 3D Contact In this chapter, you will create all the contacts between the balls, the balls and piping, and the balls and the Container.

Task Objective You will create contact definitions between:

Ball_1 and the Return piping

Ball_2 and the Return piping

Ball_1 and the Container

Ball_2 and the Container

Ball_1 and Ball_2


Chapter

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Defining Contact between Ball_1 and the Return To create the contact surface on the Return geometry:

1. Change to Body-Editing Mode of the Return body:

In the Database window, right-click Return.

From the menu that appears, click Edit. The Return piping system is now the only geometry in the working model window.

2. In the Curve and Surface toolkit, click the FaceSurf tool.

3. Set the Modeling Option toolbar to MultiFace.

4. Rotate and translate the Return geometry as needed to be able to click on all eight interior surfaces. The selected surfaces remain highlighted so you can keep track of what you have selected. The names of the faces appear in the window as shown in the figure to the right.

5. Click OK to finish the contact surface definition.

The newly defined contact surface appears as an item in the Database window under the Surfaces category, FaceSurface1 (see figure below). You will also see a new shaded surface in the interior of the piping system (in this case, the surface is green, but it could be another color). You can display a Properties dialog box for FaceSuface1 using the same methods that you used with other entities. You can modify its name and color where it would be most helpful. For this tutorial, you use the default name and color.

6. Exit the body-editing mode for the Return body by right-clicking the working model window, and then clicking Exit.

21

To create the contact between Ball1 and the Return:

In the Contact toolkit, click the Sphere To Surface tool. Enter the following:

Surface: Click the interior surface of Return.

Sphere: Click Ball_1.

Defining Contact between Ball_2 and the Return To create the contact between Ball2 and Return:

Again, click the Sphere To Surface tool. Enter the following:

Surface: Click the interior surface of Return.


Defining Contact between Ball_1 and Ball_2 To create the contact between the balls:

In the Contact toolkit, click the Sphere To Sphere tool. Enter the following:



Defining Contact between Ball_1 and the Container To create the contact surface on the Container geometry:

1. Change to Body-Editing Mode of the Container body:

In the Database window, right-click Container.

From the menu that appears, click Edit. The Container is now the only geometry in the working model window.

2. In the Curve and Surface toolkit, click the FaceSurf tool.

The Modeling Option toolbar should already be set to MultiFace.

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3. Rotate and translate the Container geometry as needed to be able to click on all 17 interior surfaces. The selected surfaces remain highlighted so you can keep track of what you have selected. The selection order of the surfaces does not matter. You pick the four sides, four interior vertical fillets, four lower horizontal corners, four interior corners and the bottom. The face numbers are 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26.

4. Click OK to finish the contact surface definition.

5. Exit the body-editing mode for the Return body by right-clicking the working model window, and then clicking Exit.

To create the contact between Ball1 and the Container:

In the Contact toolkit, click the Sphere To Surface tool. Enter the following:

Surface: Click the interior surface of Container.


Defining Contact between Ball_2 and the Container To create the contact between Ball2 and Container:

Again, click the Sphere To Surface tool. Enter the following:

Surface: Click the interior surface of Container.


Adjust Contact Surface Resolution of Return To adjust the resolution of the contact surface of Return:

1. Display the Properties dialog box for the first contact (SphereToSurface1).

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2. In the SphereToSurface tab, in the Base Surface Section, click Base Surface Patch.

The Base Surface Patch dialog box appears.

3. Change Plane Tolerance Factor from 5 to 2.

This increases the resolution of the patch surfaces that are used to represent the Return contact surface.

4. Click OK to exit the Base Surface Patch dialog box.

5. Click OK to exit the SphereToSurface dialog box.


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Analyzing and Reviewing the Model In this chapter, you will run a simulation of the model you just created. You will examine the results and think about what to change to make sure the results are correct.

Task Objective Learn to use the more advanced aspects of plotting, including playing animations with the plots and using the Trace Data tool.


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End Time: 8

Step: 200


3. Select Output File Name, and then enter the output file name: Ball_Return

4. Click Simulate.

RecurDyn calculates the motions and forces in the balls, joints, spring, and contacts. There will be 2000 plot outputs stored because the Number of Steps is 200 and the Plot Multiplier Step Factor is 10.

Reviewing the Results To review to motion in the model:

Animate the model using the Play button on the Animation toolbar. Refer to the 3D Crank Slider tutorial for more details on playing an animation. Notice that Ball_1 (the ball on the right) moves to the left and impacts Ball_2. Both balls drop into the container and cause it to sway.

The general motion behavior seems to be reasonable but there is uncertainty about the accuracy of some of the inputs. In particular, there is a question about the damping in the contacts between the Return contact surface and each of the two balls. The default value of the damping might be good. A helpful way to check the damping is to reduce its magnitude by a factor of 10 and check for differences in the results.


27

Preparing and Running a New Simulation To adjust the damping value for the two Return contacts:

1. Select the contact SphereToSurface1 in the Database window.

2. Hold down the Shift key and select SphereToSurface2.

3. Right-click the selected contacts, and then select Properties from the window that appears.

4. In the Characteristics tab, change Damping Coefficient to 0.1.

5. Click OK.


1. In the toolbar, click the combo box next to the Simulate tool, and then click Dynamic/Kinematic.



End Time: 8

Step: 200


3. Select Output File Name, and then enter the file name: Ball_Return_d1

4. Click Simulate.

5. Animate the model to see that the motion results are similar to the original simulation.


28

Comparing the Results of the Two Simulations To plot the reaction forces at the container joint:

1. In the toolbar, click the Plot tool.

A plot session begins and the top item in the Plot Database window is Ball_Return_d1.


3. Click the file name Ball_Return.RPLT (it was created from the first simulation).

4. Click Open.

A new item appears in the Plot Database window, Ball_Return. It contains the plot data from the first simulation. You will compare the results between the two simulations as you use the plot data to determine the design loads that are acting on the container.

To plot the reaction force in the container revolute joint:

1. Under Ball_Return_d1, expand Joints.

2. Expand RevJoint1.

3. Right-click FY_Reaction_Force, and then select Multi Draw.

You see two curves that represent the vertical reaction force in the Container revolute joint for both simulations (see top left window in the figure below). The legend distinguishes between the two simulations by providing the name of the simulation near each curve.

The timing of the impacts between the ball and the container are slightly different between the first and second simulations. With the reduced damping, Ball_2 reaches the container earlier. You can assume that the earlier impact is because of the higher velocity of Ball_1 when it impacts Ball_2. The higher velocity of the impact slows down Ball_1 and the impact of Ball_1 with the container occurs later in the second simulation.

There is a significant difference in the second impact in the container between the two simulations. In the first simulation, there is one large impact. In the


29

second simulation, there are two medium impacts. To learn more about what is happening, plot the contact forces between the balls and the container.

To plot the container contact forces for the two balls:

1. In the toolbar, click the Show All Panes tool to display four plotting windows.

2. Click the lower left window to make that pane active.

3. Expand Contact.

4. Expand Sphere To Surface Contact.

5. Expand SphereToSurface3.

6. Right-click FY_SurSphContact, and then select Multi Draw.

7. Expand SphereToSurface4.

8. Right-click FY_SurSphContact, and then select Multi Draw.

You see four curves that represent the vertical contact force for Ball_1 (SphereToSurface3) and Ball_2 (SphereToSurface4) for both simulations (see bottom left window in the figure below).

You gain additional insight with this set of curves because you can see that in the first simulation, the impact of Ball_1 involves only Ball_1, while in the second simulation, the two medium impacts involve first Ball_2 and then Ball_1. To learn more about what is happening, display the animation of the second simulation in combination with the plots.


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To display the animation with the plots:

1. Click the lower right window to make that pane active.

2. In the toolbar, click the Load Animation tool.

A message appears warning you that you will lose the plot in the window.

3. Dismiss the message.

The animation loads into the lower right window and the animation toolbar appears in the Plotting window.

4. Change the rendering to Shaded and change the view to be able to see clearly inside the container.

5. Click the Play button and carefully examine the animation at the point of the second impacts.

Notice that the second impacts are because of Ball_1 striking Ball_2 rather than the bottom of the container. The first of the second impacts is the force of Ball_1 as transmitted through Ball_2 and the second of the second impacts in Ball_1 later impacting the bottom of the container.

Determining the Reference Load Now that you understand the interaction of the balls and the container, you can develop a load case for use in Finite Element Analysis (FEA). An examination of the two simulation results indicates that the worst-case loading condition occurs when a ball drops down directly on the bottom surface of the inside of the container. The loads of Ball_1 and Ball_2 are similar in the first simulation even though their velocities were significantly different. This seems reasonable because the vertical drop is the same for both balls. You can use the Trace Data tool to find out the peak loads.

To find the peak loads:

1. In the toolbar, click the Trace Data tool.

2. Place the cursor at the first peak of the second simulation.

The cursor snaps to the peak and the Data Display appears as shown in the figure on the right.

The first row contains the animation frame number.

The second row contains the X value (time).

The third row contains the Y value, which is the contact force of interest.


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You now have a force value that needs to be applied to the FEA model. You need a location to apply the force.

To plot the location of Ball_2 as it impacts the container:

1. Click in the upper right window to make that pane active.

2. Expand Bodies.

3. Expand Ball_2.

4. Right-click Pos_TX, and then select Draw.

5. Right-click Pos_TY, and then select Draw.

6. Right-click Pos_TZ, and then select Draw.

7. In the toolbar, click the Trace Data tool.

8. Move the cursor along the TX and TZ curves until you are at animation frame 487. You can then read off the X and Z position of the center of Ball_2. Move that point down to the bottom of the container and you will have the location to apply the maximum load (scales with a safety factor) to your FEA model.

To define the container in dynamic equilibrium, you need to know the rotational acceleration of the container. The quickest way to obtain that information is to plot the rotational acceleration at the revolute joint.

To plot the rotational acceleration of the container:

1. Click the upper left window to make that pane active.

2. To add a Plot Page to the upper left pane, in the toolbar, click the Add Page tool.

3. Expand Joints as needed.

4. Expand RevJoint1.

5. Right-click Acc1_Relative, and then select Draw.

6. Again, use the Trace Data tool to investigate the first peak in the data. It occurs at animation frame 487, the point of Ball_2 making impact with the container.

With the rotational acceleration of the container, you can define a component in dynamic equilibrium for your FEA study. With dynamic equilibrium, your model will be less sensitive to the constraint locations in the model. You should contain the model at the pivot location and add another constraint to control the rotation.


32

Ideas for Further Exploration

Here are few more things to consider:

The force in the container revolute joint was not at zero before the balls entered the container. Why not?

How would the results change if the container material were changed from steel to aluminum?

Above the assumption was made that the balls rolled more quickly with a lower contact damping. Plot the ball velocity for both balls and both simulations. Was the assumption correct?

Answers to the first two items:

The initial vertical force reflects the weight of the container.

Initial force in the revolute joint would be lighter and the container swing would be larger due to the impact of each ball.

Thanks for participating in this tutorial!

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