COSMOSMotion Essentials TrainingCOSMOSMotion 2007

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About this coursePrerequisitesCourse Design PhilosophyUsing this bookA note about filesConventions used in this bookClass Introductions

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Design Validation ProductsCOSMOSWorks

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What is Motion Simulation ?Study of moving systems or mechanismsMotion of a system is determined byMechanical joints connecting the partsThe mass and inertia properties of the componentsApplied forces to the system (Dynamics)Driving motions (Motors or Actuators)Time

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Mechanism typesKinematic SystemMovement of part(s) under enforced or constrained motionFully controlled and only one possible motion result irrespective of force and massZero degree of freedomDynamic SystemMovement of part(s) under free motion subject to forcesPartially controlled and infinite number of results depending on forcesGreater than zero degrees of freedom

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Understanding BasicsMass and InertiaNewtons First LawConservation of momentumDegrees of freedomRigid bodyGrounded partsMoving partsConstraintsRestrictions placed on a parts movement in specific degrees of freedomMechanical joints are connections that restrict the movement of one part to anotherJoint motionGravity

xyPendulum restrainedto pivot about mountingpoint

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Constraint MappingMapping of SolidWorks assembly mates (constraints) to COSMOSMotion joints.100+ ways of defining SolidWorks mates. Basic constraint types are merged to simplified mechanical joints.One Orthogonal Concentric mate in SolidWorks becomes a Concentric joint.One Coincident and One Orthogonal Concentric mates in SolidWorks becomes a Revolute joint.One Point to Point coincident mate in SolidWorks becomes a spherical joint

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User InterfacePull down menuIntellimotion builderMotion toolbarIntellimotion browser

Lesson 1Governor Mechanism

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Lesson 1: TopicsIntroduction to the COSMOSMotion Feature ManagerUnderstand basic capabilities of COSMOSMotionRun a SimulationCreate a result plot

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Lesson 1: Defining and Simulating a MechanismPartsMoving PartsGround PartsConstraintsJointsJoint PrimitivesCam ConstraintsForcesApplied ForcesFlexible ConnectorsGravityResults

Lesson 2Crankslider Mechanism

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Lesson 2: Topics

Create moving and ground partsReview basic joint types in COSMOSMotionUnderstand Automatic Constraint mappingApply motion to a jointCreate a result plot

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Lesson 2: Constraint Mapping Concept1 Coincident and 1 concentric mates becomes a revolute joint

1 Concentric mate becomes a cylindrical joint

A point on a point coincident mate becomes a spherical joint

A point on an axis coincident mate becomes an Inline Joint

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Lesson 2: Results Collar-1 not only translates along collar_shaft-1 but also rotates. The rotation needs to be prevented

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Lesson 2: Motion on Joints

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Lesson 2: ResultsPower Consumption in MechanismWhy is Power Consumption negative in some places?

Lesson 3Piston Crankshaft Mechanism

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Lesson 3 TopicsReview basic joint types in COSMOSMotionCreate Mechanical Joints Apply motion to a jointCreate and review results

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Lesson 3: Basic Joint Types

Joints used to constrain the relative motion of a pair of rigid bodies by physically connecting them.Joint Primitives used to enforce standard geometric constraints

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Lesson 3: Joint definitionLocationDirection

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Lesson 3 Results

Torque required to drive the mechanism

Lesson 4Coupler

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Lesson 4 TopicsSimulate motion of gears using joint couplersJoint coupler to associate the movement of one joint with anotherModeling gear-mate from SolidWorks model

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Lesson 4: CouplersAny one of the following joint combinations will create a coupler:Revolute-RevoluteRevolute-TranslationalRevolute-CylindricalTranslational-CylindricalTranslational-TranslationalCylindrical-CylindricalOnly motion transfer. No load transfer

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Lesson 4: Coupler Definition

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Lesson 4: Gear Mate in SolidWorksSimulate Couplers using Gear Mate in SolidWorks

Lesson 5Door Mechanism

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Lesson 5 TopicsCreate springs and damper entities in COSMOSMotionAttach different parts together to move them as a single entityConstrain the motion of a cylindrical joint to achieve correct mechanism behaviorModify springs and dampers to achieve desired design goals

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Lesson 5 Attaching PartsPhysically attach one part to another Two parts will be welded or rigidly connected to one another. No relative motion between the two parts Initial orientation between the two parts will be locked and will be maintained throughout the simulation

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Lesson 5: SpringsTranslational Spring Force = -k (X - X0)n + F0Where:k = Spring stiffness coefficient (always > 0)X = Current distance between the spring connection points X0 = Reference length of the spring (Free length) n = Exponent defining spring characteristicF0 = Reference force of the spring (preload)Positive force repels the two parts.Negative force attracts the two parts.Similar force expression applies to Torsional Springs

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Lesson 5: DampersTranslational Damper Force = c*vn Where:c - Translational damping coefficientv - Current relative velocity between parts at the attachment pointsn - Exponent. Similar force expression applies to Torsional Dampers

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Lesson 5: Results gas_piston-1 not only translates along gas_cylinder-1 but also rotates. The rotation needs to be prevented

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Lesson 5: Results Velocity goal is satisfiedDoor does not stop in 30 secondsShould we increase or decrease spring stiffness?Spring stiffness: 1 N/mmDamper Co-efficient: 5 N (sec/mm)

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Lesson 5: Results Velocity goal is satisfiedDoor stops in 30 secondsSpring stiffness: 2 N/mmDamper Co-efficient: 10 N (sec/mm)

Lesson 6Hatchback Mechanism

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Lesson 6 TopicsCreate an Action Only force to simulate an Change the mass properties of a partUse Impact forces to control two parts from interfering each other

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Lesson 6: ForcesAffect the dynamic behavior of a mechanismDo not prohibit or prescribe motion and so do not add or remove degrees-of-freedom from your model.Force EntitiesTranslational and Torsional Springs Translational and Torsional Dampers Action-Only Forces/Moments Action-Reaction Forces/Moments Impact ForcesFlexible ConnectorsGravity

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Lesson 6: Force DefinitionForce TypeWhether the loading is a force or a moment.LocationDirectionAlong an axis defined by an edge, plane or cylindrical surface.Along the line-of-sight between two points MagnitudeEnter a pre-defined function expression (step, harmonic, spline).Enter an equation directly into the Function Expression field using the library of built-in COSMOSMotion functions.

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Lesson 6: Action Only Force

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Lesson 6: Material PropertiesAdding MaterialsModifying Material Properties

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Lesson 6: Results

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Lesson 6: Impact ForcesIntermittent force that is dependent on relative distance between two components). Impact forces are used to simulate the collision between two parts. As two parts approach within a specified distance, the impact force becomes active, and a force specified by the impact parameters is applied to both of the colliding parts. The collision is dependent on the materials and geometry of the bodies colliding.

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Lesson 6: Impact ParametersImpact Force = Spring Force + Damping ForceStiffness: Depends on material properties and curvature of interacting surfacesExponent: Determines impact force characteristicMax Damping: Simulates energy loss in collisionPenetration: Depth at which maximum damping occurs. Length: distance at which the impact force is activated (parts contact)

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Lesson 6: Impact ParametersImpact Force = Spring Force + Damping ForceStiffness: Depends on material properties and curvature of interacting surfacesExponent: Determines impact force characteristicMax Damping: Simulates energy loss in collisionPenetration: Depth at which maximum damping occurs. Length: distance at which the impact force is activated (parts contact)

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Lesson 6: Impact ParametersGood numbers for impact parameters:Stiffness: 10000 lb/in10000 N/mmExponent: 1.1-1.3 1.1-1.3 Damping:0.1-100 lb-s/in1-100 Penetration: 0.0001 in0.01 mm

d cannot be specified as 0

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Lesson 6: ResultsTranslational displacement of the concentric joint between the piston and cylinder partsNotice that the displacement is held at 8 inches which means that the impact force does not allow further translation between the parts

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Lesson 6: ResultsMagnitude of the impact force applied

Lesson 7Contacts

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Lesson 7 TopicsApply Point to curve contact

Apply Curve to curve contact

Apply 3D Contact

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Lesson 7: Understanding ContactsPoint-curve - Restricts a point on one rigid body to lie on a curve on a second rigid body.

Curve-curve - Constrains one curve to remain in contact with a second curve.

Intermittent curve-curve - Applies a force to prevent curves from penetrating each other. Only active if the parts are touching

3D Contact Applies a force to prevent bodies from penetrating each other. Only active if the parts are touching

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Lesson 7: Impact Forces Vs ContactsContact is similar to an impact force in that the material properties of the parts are used to define the contact parameters.

Contact differs from an impact force since any point along a curve or geometry is used in the contact

Contact simulates friction forces between parts.

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Lesson 7: 3D ContactSurface Representation of parts:Tessellated GeometryFaster but less accurate in certain contact situations like point to surface or multiple contacts Precise GeometryLonger simulation time but produces accurate results

Contact Containers

Lesson 8 Railcar Mechanism

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Lesson 8: TopicsApply Gravity force to the mechanism

Create an Action-Reaction force to accelerate the railcar

Learn some advanced plotting techniques in COSMOSMotion

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Lesson 8: Action Reaction Force

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Lesson 8: ResultsProbing translational velocity plot of body-1

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Lesson 8: ResultsPlotting multiple plots in the same XY graph

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Lesson 8: ResultsReplacing X axis time scale with a desired results quantity

Lesson 9 Floor Jack Mechanism

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Lesson 9 Topics Apply motion to a partUse different types of motion functionsMake a design change and study mechanical advantage

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Lesson 9: Part Motion

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Lesson 9: Function Types ConstantStep Functiond0 = Initial value of displacement d1 = Final value of displacement t0 = Start step time t1 = Final step timeHarmonicAmplitude; Frequency; Time Offset; Phase Shift; Average

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Lesson 9: Function Types SplineYou can use your own motion data to control your mechanism by importing data points. To import data points, they must be in a .TXT or .CSV file format.You may import an unlimited number of data points.

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Lesson 9: ResultsTranslational Displacement of the cylinder joint connecting the piston and cylinderForce on handle Force to move the piston. A very small force is required to push the handle. This gets amplified internally at the piston cylinder area