ball return tutorial (basic) - recurdyn technical...

B A L L R E T U R N T U T O R I A L ( B A S I C )

Ball Return Tutorial (Basic)

2

Copyright © 2016 FunctionBay, Inc. All rights reserved

User and training documentation from FunctionBay, Inc. is subjected to the copyright laws of the Republic of Korea and other countries and is provided under a license agreement that restricts copying, disclosure, and use of such documentation. FunctionBay, Inc. hereby grants to the licensed user the right to make copies in printed from of this documentation if provided on software media, but only for internal/personal use and in accordance with the license agreement under which the applicable software is licensed. Any copy made shall include the FunctionBay, Inc. copyright notice and any other proprietary notice provided by FunctionBay, Inc. This documentation may not be disclosed, transferred, modified, or reduced to any form, including electronic media, or transmitted or made publicly available by any means without the prior written consent of FunctionBay, Inc. and no authorization is granted to make copies for such purpose.

Information described herein is furnished for general information only, is subjected to change without notice, and should not be construed as a warranty or commitment by FunctionBay, Inc. FunctionBay, Inc. assumes no responsibility or liability for any errors or inaccuracies that may appear in this document.

The software described in this document is provided under written license agreement, contains valuable trade secrets and proprietary information, and is protected by the copyright laws of the Republic of Korea and other countries. UNAUTHORIZED USE OF SOFTWARE OR ITS DOCUMENTATION CAN RESULT IN CIVIL DAMAGES AND CRIMINAL PROSECUTION.

Registered Trademarks of FunctionBay, Inc. or Subsidiary

RecurDyn™ is a registered trademark of FunctionBay, Inc.

RecurDyn™/SOLVER, RecurDyn™/MODELER, RecurDyn™/PROCESSNET,

RecurDyn™/AUTODESIGN, RecurDyn™/COLINK, RecurDyn™/DURABILITY,

RecurDyn™/FFLEX, RecurDyn™/RFLEX, RecurDyn™/RFLEXGEN, RecurDyn™/LINEAR,

RecurDyn™/EHD(Styer), RecurDyn™/ECFD_EHD, RecurDyn™/CONTROL,

RecurDyn™/MESHINTERFACE, RecurDyn™/PARTICLES, RecurDyn™/PARTICLEWORKS,

RecurDyn™/ETEMPLATE, RecurDyn™/BEARING, RecurDyn™/SPRING, RecurDyn™/TIRE,

RecurDyn™/TRACK_HM, RecurDyn™/TRACK_LM, RecurDyn™/CHAIN, RecurDyn™/MTT2D,

RecurDyn™/MTT3D, RecurDyn™/BELT, RecurDyn™/R2R2D, RecurDyn™/HAT,

RecurDyn™/CRANK, RecurDyn™/PISTON, RecurDyn™/VALVE, RecurDyn™/TIMINGCHAIN,

RecurDyn™/ENGINE, RecurDyn™/GEAR are trademarks of FunctionBay, Inc.

Third-Party Trademarks

Windows and Windows NT are registered trademarks of Microsoft Corporation.

ProENGINEER and ProMECHANICA are registered trademarks of PTC Corp. Unigraphics and I-DEAS are registered trademark of UGS Corp. SolidWorks is a registered

trademark of SolidWorks Corp. AutoCAD is a registered trademark of Autodesk, Inc.

CADAM and CATIA are registered trademark of Dassault Systems. FLEXlm is a registered trademark of GLOBEtrotter Software, Inc. All other brand or product names are trademarks or registered trademarks of their respective holders.

Edition Note

These documents describe the release information of RecurDyn™ V8R5.

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

Importing Geometry......................................................................................... 9

Task Objective ...................................................................................................................... 9


Importing the CAD Geometry .............................................................................................. 10

Saving the model ................................................................................................................ 11

Creating the Ball Geometry ................................................................................................. 12

Saving the model ................................................................................................................ 13

Defining Joints and Forces ............................................................................ 14

Task Objective .................................................................................................................... 14

Estimated Time to Complete ............................................................................................... 14

Attaching the Return Piping to Ground ............................................................................... 15

Attaching the Container to Ground ..................................................................................... 15

Defining the Rotational Spring ............................................................................................ 16

Defining 3D Contact ...................................................................................... 17

Task Objective .................................................................................................................... 17


Defining Contact between Ball_1 and the Return ............................................................... 18

Defining Contact between Ball_2 and the Return ............................................................... 19

Defining Contact between Ball_1 and Ball_2 ...................................................................... 19

Defining Contact between Ball_1 and the Container .......................................................... 19

Defining Contact between Ball_2 and the Container .......................................................... 20

Adjust Contact Surface Resolution of Return ..................................................................... 20

Saving the Model ................................................................................................................ 21

Analyzing and Reviewing the Model.............................................................. 22

Task Objective .................................................................................................................... 22


Performing Dynamic/Kinematic Analysis ............................................................................ 23

Reviewing the Results ........................................................................................................ 23

Preparing and Running a New Simulation .......................................................................... 24

Comparing the Results of the Two Simulations .................................................................. 25

4

Determining the Reference Load ........................................................................................ 28

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 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.

Chapter

1


6

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.

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 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

Estimated Time to Complete

This tutorial takes approximately 51 minutes to complete.


Setting Up Your Simulation

Environment

Task Objective

Learn how to set up the simulation environment.


1 minute

Chapter

2


8

Starting RecurDyn

To start RecurDyn and create a new model:

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

RecurDyn starts and the Start RecurDyn dialog box appears.

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

3. Click OK.


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.


5 minutes

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:

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: Return.x_t (The file location: <Install Dir> /Help /Tutorial /Professional /Basic /Tut4_Ball_Return)

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 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 View Control Toolbar, click the Zoom tool.

Type the z key on the keyboard.

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

On the View Control Toolbar, click the Shade tool.

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

On the View Control Toolbar, click the Rotate tool.


11

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 file location: <InstallDir>/Help/Tutorial/Professional/Basic/Tut4_Ball_Return)

The geometry representing the container appears in the working 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


Saving the model

1. From the File menu, click Save As.

2. Save the model different directory, because you cannot simulation in tutorial directory.


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:

1. From the Body group in the Professional tab, click the Ellipsoid. Enter the following:

Point: Enter 3000, 1000, 0 in the Input Window toolbar

Distance: Enter 90 in the Input Window toolbar

2. From the Body group in the Professional tab, click the Ellipsoid tool. Enter the following:

Point: Enter 700, 0, 0 in the Input Window toolbar

Distance: Enter 90 in the Input Window toolbar

To update the ball bodies:

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

In the General tab, change Name to Ball_1.

In the Graphic Property tab, change Color to Red.

In the Body tab:

Change Material Input Type to User Input.

Change Mass to 10.

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

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.


2. Display the Properties dialog box for Body2:

In the General tab, change Name to Ball_2.


13

In the Graphic Property tab, change Color to Red.

In the Body tab:

Change Material Input

Type to User Input.

Change Mass to 10.

Change Mass Moment of

Inertia (Ixx, Iyy, Izz) to

70000.


Your model appears as shown in the figure below.

Saving the model

From the File menu, click Save.


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.


10 minutes

Chapter

4


15

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. From the Joint group in the Professional tab, click the Fixed Joint.

2. Set the Creation Method toolbar to Body, Body, Point.

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

4. Click the Return geometry.

5. Click the point 1600, 0, 0 in the working 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 View Control Toolbar, click on the Select Zoom tool.

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.

1. From the Joint group in the Professional tab, click the Revolute Joint

2. Set the Creation Method toolbar to Point.

3. 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 about -2600, -850, 1430 you should then click the left mouse button to create the revolute joint.


16

4. 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 -2600, -850, 1430 in the Input Window toolbar.

Defining the Rotational Spring

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

To create the rotational spring:

1. From the Force group in the Professional tab, click the Rotational Spring.

2. Set the Creation Method toolbar to Joint.

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


17

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


10 minutes

Chapter

5


18

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 window.

2. From the Curve and Surface group in the Geometry tab, click

the Face Surfurce.

3. Set the Creation Method toolbar to Solid(Sheet), MultiFace

4. Enter ImportedSolid1 in the Input Window toolbar. And then the FaceSurf Operation dialog box appears.

5. To select all eight interior surfaces, click an

interior face after selecting the Add/Remove

(Continuous) option.

6. 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.

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

clicking Exit.


19

To create the contact between Ball1 and the Return:

From the Contact group in the Professional tab, click the Sphere To Surface. 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. 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:

From the Contact group in the Professional tab, click the Sphere To Sphere. 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 window.

2. From the Surface group in the Geometry tab, click the Face Surface.

The Modeling Option toolbar should already be set to MultiFace.

3. To select all 17 interior surfaces, click interior faces after selecting the Add/Remove option.


20

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 window, and then clicking Exit.

To create the contact between Ball1 and the Container:

From the Contact group in the Professional tab, click the Sphere To Surface. 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. 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).


21

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.

Saving the Model

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


22

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.


5 minutes

Chapter

6


23

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 use Output File Name function efficiently, the Create Output Folder option is turned off.

a. From the Model Settings group in the Home tab, click Simulation. The Simulation dialog box will appear.

b. Select the General tab. Make sure the Create Output Folder check box is not checked.

c. Click OK

To perform a dynamic/kinematic analysis:

1. Click the Dyn/Kin. from the Simulation

Type group in the Analysis tab.

The Dynamic/Kinematic Analysis dialog box appears.

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

End Time: 8

Step: 200

Plot Multiplier Step Factor: 10

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 of the Animation Control in the Analysis tab. 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.


24

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.

To perform a dynamic/kinematic analysis:

1. Click the Dyn/Kin.from the Simulation Type in the Analysis tab.

The Dynamic/Kinematic Analysis dialog box appears.

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

End Time: 8

Step: 200

Plot Multiplier Step Factor: 10

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.


25

Comparing the Results of the Two Simulations

To plot the reaction forces at the container joint:

1. Form the Plot group in the Analysis tab, click the Plot.

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

2. From the File menu, click Import.

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.


26

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 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. From the View group in the Howe tab, click the Show All Windows 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.

To display the animation with the plots:

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

2. From the Animation group in the Tool tab, click the Load Animation.

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.


27

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.


28

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. From the View in the Home tab, click the

TraceData.

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.

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 window 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. From the View in the Home tab, click the TraceData.

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.


29

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 539, 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.


30

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!

ball return tutorial (basic) - recurdyn technical...

Documents