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Autodesk® Inventor® Dynamic Simulation: Its Bark Is Worse than Its Bite! Dan Banach Autodesk Inc. MA2946-L Learning Objectives At the end of this class, you will be able to: Navigate the user interface in the dynamic simulation environment Edit joints and loads Understand simulation results Perform post-processing of simulation results About the Speaker Dan Banach Dan is an Autodesk Education Programs Manager at Autodesk, and is an Autodesk® Inventor® 2013 Certified Professional, an Autodesk Certified Instructor on Inventor, Autodesk Certification Evaluator, a nationally recognized instructor, and a longtime speaker at Autodesk University. Before joining Autodesk, Dan provided CAD solutions at MasterGraphics (an Autodesk Gold partner) to clients for more than 19 years. He has authored three books on Autodesk Mechanical Desktop and has co-authored sixteen books on Autodesk Inventor. Dan has also created Autodesk Inventor and Autodesk Inventor Publisher computer-based training courses for CADLearning.

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Page 1: Autodesk® Inventor® Dynamic Simulation: Its Bark Is · PDF fileAutodesk® Inventor® Dynamic Simulation: Its Bark Is Worse than Its Bite! 2 What is Dynamic Simulation 1. Dynamic

Autodesk® Inventor® Dynamic Simulation: Its Bark Is

Worse than Its Bite! Dan Banach – Autodesk Inc.

MA2946-L

Learning Objectives

At the end of this class, you will be able to:

Navigate the user interface in the dynamic simulation environment

Edit joints and loads

Understand simulation results

Perform post-processing of simulation results

About the Speaker

Dan Banach

Dan is an Autodesk Education Programs Manager at Autodesk, and is an Autodesk® Inventor® 2013

Certified Professional, an Autodesk Certified Instructor on Inventor, Autodesk Certification Evaluator, a

nationally recognized instructor, and a longtime speaker at Autodesk University. Before joining

Autodesk, Dan provided CAD solutions at MasterGraphics (an Autodesk Gold partner) to clients for more

than 19 years. He has authored three books on Autodesk Mechanical Desktop and has co-authored

sixteen books on Autodesk Inventor. Dan has also created Autodesk Inventor and Autodesk Inventor

Publisher computer-based training courses for CADLearning.

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What is Dynamic Simulation 1. Dynamic Simulation is a module in Autodesk Inventor Professional that gives you the ability to

replicate real world forces on Autodesk Inventor assemblies, which allows a thorough evaluation

of an assembly’s performance.

2. Examples of what you would use Dynamic Simulation are:

a. How long does it take to perform an action?

b. Are the loads and input forces powerful enough to drive the machine?

c. Is the machine strong enough? d. What force is required in the hydraulic jack to close a gate in two seconds? e. What is the path that a component travels? f. What is the maximum velocity a component reaches? g. What is the rate of acceleration of a component?

Dynamic Simulation Workflow

Follow this main workflow to create a dynamic simulation in Autodesk Inventor Professional.

1. Model assembly: Model the components that will be analyzed and assemble them.

2. Create /edit joints: Identify the locations where components move relative to one another.

Choose the type of joint from a standard joints, rolling joint, sliding joints, 2D contact and Forces

joint

3. Define environment: Add physical information about the machine: gravity, friction, damping, and

external forces.

4. Run simulation: Review the motion of the model by setting up the cycle time, number of steps

to show, and other items.

5. Analyze results: Plot and review information about the machine reactions as it runs, including

positions, velocities and acceleration, reaction forces and torques, and driving forces.

Trebuchet Assembly

Stress Analysis In this section you run a stress analysis that will be compared to the results after the dynamic simulation

analysis is run. To save time, the constraints and loads have been applied to this part.

1. Make the project file “MA2946-L.ipj” current - C:\DataSets\MA2946-L.ipj.

1. In the Open dialog box click the Trebuchet folder in the Frequently Used Subfolders area in the

Open dialog box and then double-click on Treb Arm.ipt.

2. Enter the Stress Analysis environment by clicking the Stress Analysis command on the

Environment tab > Begin panel.

Create an

assembly in

Inventor

Create /

Edit Joints

Define

environment

Run

simulation

Analyze

results

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3. In the browser expand the Constraints node and click on Pin Constraint:1 (The middle hole is

highlighted, showing that the part can rotate about this hole) and Fixed Constraint:1 (The end

hole is highlighted, showing that the part can cannot about this hole).

4. You can also find the reaction forces and reaction moment for each constraint by right-clicking on

the constraint and click Reaction Forces from the menu. The reaction force or reaction moment is

the force or moment which is required to reach equilibrium.

5. In the browser expand the Loads node and click on Force:1. This shows the direction of the force

that we believe will be applied to the part.

6. To see the magnitude of the applied forces, double-click on either the Force in the browser or on

one of the arrows in the graphics window. Notice that 100 lbforce has been applied to the outside

hole.

7. Run the simulation by clicking the Simulate command on the Stress Analysis tab >Solve panel

and then click Run from the Simulate dialog box.

8. Review the results by double-clicking on the Results entries in the browser. The following image

shows that the safety factor has a minimum value of 2.2.

Note: The results are only as good as the loads and constraints that were input.

9. Save and then close the file.

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Dynamic Simulation Environment In this section you explore the user interface and main tools in the Dynamic Simulation environment.

1. Open the file .\Trebuchet\Trebuchet Assembly Start.iam.

2. Enter the Dynamic Simulation environment by clicking Environment tab >Begin panel > Dynamic

Simulation.

3. The following image shows the initial components in the Dynamic Simulation environment.

a. Ribbon: Since we are still in Inventor the panel and tools change to reflect the Dynamic

Simulation environment.

b. Grounded: Components that have zero degrees of freedom and components that have

NO applied assembly constraints.

c. Mobile: Components with degrees of freedom allowing them to participate in the

simulation when forces are applied.

i) Welded Groups: When a rigid relationship (no degrees of freedom between

components) exists between components the components are placed in a

welded group.

d. Standard Joints: Joints created by automatic constraint conversion when entering the

dynamic simulation environment.

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e. External Loads: Loads that you can apply are Gravity, forces and torque applied to

components.

f. Simulation Player: Controls how the simulation is run.

Note: More information about these tools and other tools will be discussed throughout this paper.

Assembly Constraints vs. Joints Autodesk Inventor assembly constraints reduce the degrees of freedom of components in an assembly.

Joints are what Dynamic Simulation uses to allow components to move or rotate. Open degrees of

freedom in an assembly = mobility in Dynamic Simulation. Assembly constraints can automatically be

converted to joints in Dynamic Simulation. Below is a list of common assembly constraints and what joint

it is converted to.

Assembly Constraint(s) Standard Joint

Converted to

Dynamic Simulation

# of Degrees of

Freedom

Removed

Between

Components

Mobility

- Insert (circular edge, circular edge)

- Mate (line, line) and mate (plane, plane)

- Mate (cylindrical face, cylindrical face) and

mate (plane, plane)

Revolution

5 1

- Mate (line, line)

- Mate (cylindrical face, cylindrical face)

Cylindrical 4 2

- Mate Face to Face Planar 3 3

- Mate (line to line and an angle constraint)

- Combination of two mates (plane, plane) that

are not parallel

Prismatic

5 1

- Mate (point, point)

- Mate (spherical face, spherical face)

Spherical 3 3

- Mate (plane, plane) Planar 3 3

- Mate (line, point)

- Mate (line, spherical face)

Point Line 2 4

- Mate (plane, line) Line Plane 2 4

- Mate (plane, point) Point Plane 1 5

Note: A grounded component and a component that has no assembly constraints applied will be

grounded in the Dynamic Simulation environment.

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Mechanism Status Before running a simulation, use the Mechanism Status command to see if there are degrees of

redundancy (when assembly constraints are converted to joints they can over constrain the assembly at

specific area, which tells Inventor that there are multiple solutions to solve for), degrees of mobility

(movement or rotation), number of bodies (number of components in the assembly) and number of mobile

bodies (number of components that can move or rotate).

1. Click the Mechanism Status command from the Dynamic Simulation tab > Joint panel.

2. Review the information in the Mechanism Status and Redundancies dialog box, and then click

OK.

3. With experience you may decide to not automatically have the assembly constraints converted to

joints. To not convert assembly constraints to joints click the Simulation Settings command on the

Dynamic Simulation tab >Manage panel.

4. Uncheck the Automatically Convert Constraints to Standard Joints option and then click No, when

prompted to Maintain Standard Joints automatically created from Assembly Constraints?

5. Click OK and the Mobile Groups and Standard Joints nodes will be removed from the browser

and all of the components will be moved to the Grounded folder as shown in the following image

on the left.

6. Click the Mechanism Status command from the Dynamic Simulation tab > Joint panel.

7. Review the information in the Mechanism Status and Redundancies dialog box as shown in the

following image on the right. When done click OK.

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8. To automatically convert assembly constraints back to joints click the Simulation Settings

command on the Dynamic Simulation tab >Manage panel and then in the dialog box click (check)

the Automatically Convert Constraints to Standard Joints option and then OK.

9. Notice the Mobile Groups and Standard Joints nodes are recreated in the browser.

10. Click the Mechanism Status command from the Dynamic Simulation tab > Joint panel.

11. The information in the Mechanism Status and Redundancies dialog box is the same as when you

first started the Dynamic Simulation. When done click OK.

12. To better see which components are mobile (can move or rotate) you can change the color of

these components. To change the color of mobile components, right-click on the Mobile Groups

node in the browser and click Color mobile groups. The mobile components will automatically

change to different colors.

13. Remove the color of mobile components, right-click on the Mobile Groups node in the browser

and click Color mobile groups.

Create a Simulation In this section you create a simulation by defining gravity and creating additional joints.

1. Continue working on the Trebuchet Assembly Start.iam or if the components were moved, close

the assembly without saving the changes and reopen the file .\Trebuchet\Trebuchet Assembly

Start.iam.

2. Run the simulation by clicking the Play button in the Simulation Player dialog box.

3. When the simulation is played, no parts moved because gravity has not been defined. Notice that

the data in the browser is greyed out; this is because the Simulation Player environment is active.

To exit this environment, click the Construction Mode button in the Simulation Player dialog box.

Note: You need to wait for simulation to complete before you can click rewind

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4. Define gravity by double-clicking on the Gravity node in the browser.

5. In the Gravity dialog box, do the following:

a. Uncheck the Suppress option

b. Click the Entity Selection button and then select the top surface of the Ground part.

c. Reverse the direction of gravity by clicking the Flip Direction button.

d. Click OK

6. Run the simulation by clicking the Play button in the Simulation Player dialog box.

7. The simulation plays, notice the Projectile Arm goes through the Ground because there is no

relationship (joint) between the Projectile Arm and the Ground. In the Simulation Player dialog

box click Rewind to the beginning of the simulation button.

8. Exit the simulation player environment by clicking the Construction Mode button in the Simulation

Player dialog box.

9. To create a joint, click the Insert Joint command on the Dynamic Simulation tab >Joint panel.

10. In the Insert Joint dialog box select the 3D Contact joint from the dropdown menu and then select

the Projectile Arm part and the Ground part (it does not matter where you select on the parts) and

then click OK. It does not matter where you select on the part.

11. Run the simulation by clicking the Play button in the Simulation Player dialog box.

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12. As the simulation plays, the Projectile Arm now drags on top of the Ground component but goes

through the Projectile. In the Simulation Player dialog box click the Rewind to the beginning of the

simulation button.

13. Next you need create three more 3D Contacts joints. Click the Insert Joint command on the

Dynamic Simulation tab >Joint panel.

14. In the Insert Joint dialog box select the 3D Contact joint from the dropdown menu and do the

following:

a. Select the Projectile Arm and the Projectile, and then click apply

b. Select the Projectile and the Ground, and then click apply

c. Select the Projectile Arm and the Stopper and then click OK.

15. Run the simulation by clicking the Play button in the Simulation Player dialog box.

16. As the simulation plays, the Projectile Arm contacts the Projectile but bounces back because the

Projectile is grounded (no assembly constraints were applied). In the Simulation Player dialog box

click the Rewind to the beginning of the simulation button.

17. Next you need create a Spatial joint to allow the projectile to move. Click the Insert Joint

command on the Dynamic Simulation tab >Joint panel.

18. In the Insert Joint dialog box select the Spatial joint from the list and then select the Projectile Arm

and in the Insert Joint dialog box click the Component 2 selection button and then select the

Projectile and then click OK. It does not matter where you select on the part.

19. Run the simulation by clicking the Play button in the Simulation Player dialog box.

20. As the simulation plays, the Projectile is thrown into the air. If desired, change your viewpoint and

rerun the simulation.

21. Save the file.

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Trace Points and the Output Grapher

To get more information about the simulation, you can add trace points that will show a range of motion or

a path. You can also use the Output Grapher to examine a variety of results from the simulation

including; results for forces, position of joints, acceleration, and velocity.

1. If you successfully completed the last section, you can continue working on the same file. If you

were not able to complete the previous section, open the file .\Trebuchet\Trebuchet Assembly -

Force Joints Added.iam

2. Enter the Dynamic Simulation environment by clicking Environment tab > Begin panel > Dynamic

Simulation.

3. Open the Output Grapher by clicking the Output Grapher command on the Dynamic Simulation

tab > Results panel.

4. Add a trace by right-clicking on the Traces option in the left side of the Dynamic Simulation

Output Grapher dialog box and click Add Trace from the menu.

5. First select the location to add the trace, in the graphics window select the end of the Projectile

Arm as shown in the following image on the left.

6. In the Trace dialog box do the following (shown in the following image on the right).

a. In the Display trace column (displayed in graphics window), check the Trajectory option

b. In the Output trace value column (display in the Output Grapher), check the Trajectory,

Velocity and Acceleration options.

c. Select the Change Color option for the Trajectory and change it to green.

d. Click Apply

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7. Add another trace to the Projectile, use the same Display trace and the Output trace value

column as you did in step 6 but change the color, to a color of your choice.

Note: If desired you can change the name of the traces by clicking on the trace entry in the

Output Grapher dialog box and enter a new name.

8. In the Output Grapher dialog box expand the Traces > Positions node for both the Trace:1 and

Trace:2 and check the P[Z] (position of the Z axis).

9. Change the viewpoint to look directly at the Front view by clicking the FRONT plane on the

ViewCube.

10. With the Output Grapher dialog box open, run the simulation by clicking the Play button in the

Simulation Player dialog box. The trace parts will appear on the screen and in the Output Grapher

dialog box as the simulation is run.

Note: In the Simulation Player dialog box, you can adjust the length the simulation will run and

the number of steps that will be captured.

11. In the Output Grapher dialog box double-click on a point on the graph and the components will

move to reflect the selected time.

12. If desired turn on the visibility of the velocity and acceleration of the Projectile.

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13. In the chart area in the Output Grapher dialog box, right-click on one of the trace points or on one

of the column name’s and click Unselect all Curves from the menu.

14. In the left column in the Output Grapher dialog box expand the Standard Joints node and then

expand Revolution:3 (Welded group:2, Welded group:1) and then from the Force folder check

Force[Z]. The name of the Revolution number may be different.

Note: From the stress analysis you did in the first section, you know the minimum safety factor is

near the end of the long section of the TrebArm.ipt, which happens to be near Revolution Joint:3.

15. The results should appear in the graph area in Output Grapher dialog box, similar to what is

shown in the following image on the left. If the results are not in the graph rerun the simulation by

clicking the Play button in the Simulation Player dialog box.

16. In the chart area in the Output Grapher dialog box, right-click on one of the Force[Z] points or on

the column name and click Search Max. from the menu as shown in the following image on the

right. The components will move to this point in time.

17. Save the file.

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Export to FEA To get more accurate stress analysis results, you can export the forces and loads from the Dynamic

Simulation environment to the Stress Analysis environment. In this section you will export the reactionary

forces on the Treb Arm.ipt to the Stress Analysis environment.

1. If you successfully completed the last section, you can continue working on the same file. If you

were not able to complete the previous section, open the file .\Trebuchet\Trebuchet Assembly -

Force Joints and Traces.iam.

2. If needed, enter the Dynamic Simulation environment by clicking Environment tab > Begin panel

> Dynamic Simulation and open the Output Grapher by clicking the Output Grapher command on

the Dynamic Simulation tab > Results panel.

3. Since the Treb Arm, is in a welded group, you need to clear the existing results and then use the

Export to FEA command before running the simulation.

a. In the Simulation Player click the Construction Mode button as shown in the following

image on the left.

b. In the Output Grapher dialog box, click the Clear button as shown in the following image

on the right.

4. In the left column in the Output Grapher dialog box expand the Standard Joints node and then

expand Revolution:3 and then from the Force folder ensure that Force[Z] is checked.

5. In the Output Grapher dialog box click the Export to FEA button.

6. The Export to FEA dialog box appears, in the graphics window select the Treb Arm and then click

OK.

7. Next you have to connect each joint to the hole on the part. In the FEA Load-Bearing Faces

Selection dialog box you select a joint and then select the hole on the part where the joint is. After

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connecting a joint with its hole, the yellow explanation point disappears. After connecting the

four joints click OK.

a. Revolution:3 = Far left hole

b. Revolution:4 = Middle hole

c. Revolution:5 = Far right hole

d. Revolution:12 = Top hole (for the stopper)

8. Run the simulation by clicking the Play button in the Simulation Player dialog box.

9. In the chart area in the Output Grapher dialog box, right-click on one of the Force[Z] points or on

the column name and click Search Max. from the menu.

10. Next you set which time step will be exported. In the Output Grapher dialog box, do the following.

a. On the Max stress row, click (check) the Export to FEA box.

b. From the top toolbar, click the Export to FEA button.

11. The Export to FEA dialog box appears again, in the graphics window select the Treb Arm and

then click OK.

12. Exit the Dynamic Simulation environment by clicking the Finish Dynamic Simulation command on

the Dynamic Simulation tab > Exit panel.

13. Enter the Stress Analysis environment by clicking the Stress Analysis command on the

Environment tab > Begin panel.

14. Create a new simulation by clicking the Create Simulation command on the Stress Analysis tab >

Manage panel.

15. In the Create New Simulation dialog box, check the Motion Loads Analysis option, the Treb Arm:1

part and the exported time step will automatically be selected. Then click OK.

Note: You can export as many steps as desired; you would then select a step from the Time Step

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list which you want to analyze.

16. The loads and forces where automatically applied from Dynamic Simulation all you need to do is

run the simulation by clicking the Simulate command on the Stress Analysis tab >Solve panel and

then click Run from the Simulate dialog box.

17. Analyze the results by double-clicking on the Results entries in the browser. The following image

shows that the safety factor has a minimum value of 15.

Note: With a safety factor of 15 you can remove material to reduce the weight and then rerun the

analysis.

18. If desired you can create a report about the simulation by clicking the Stress Analysis tab >Report

panel.

19. Save and close the file

Optional Exercise

Increase the Velocity of the Projectile In this exercise, your goal is to modify the trebuchet to increase the velocity of the projectile.

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1. In the Open dialog box click the Boom Arm folder in the Frequently Used Subfolders area in the

Open dialog box and then double-click on Trebuchet Assembly – Max Velocity.iam.

2. Edit components in the trebuchet to increase the velocity of the projectile.

3. In the Output Grapher, confirm the velocity of the Projectile – Trace:2 V[Z]. The starting,

maximum velocity is 153.03700 in/s.

4. When done, close the file and do not save the changes.

Boom Arm Assembly

Redundant Constraints At some point when you perform a Dynamic Simulation analysis and the assembly constraints are

automatically converted to joints, you will see a dialog box stating that there are redundant joints.

Redundant joints are created when two or more assembly constraints are converted to joints and the

movement of the joint is over constrained. In the chart, in the first section of the paper you see how many

degrees of mobility are left after applying an assembly constraint. When Dynamic Simulation creates

these joints from each assembly constraint the joints cannot contradict each other. In this section you will

see where two Mate (line-line) constraints create a conflict / redundant joint.

1. In the Open dialog box click the Boom Arm folder in the Frequently Used Subfolders area in the

Open dialog box and then double-click on Boom Arm Assembly - Start.iam.

2. Enter the Dynamic Simulation environment by clicking the Dynamic Simulation command on the

Environment tab > Begin panel.

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3. In this file the automatic conversion of assembly constraints to joints is off. To automatically

convert assembly constraints back to joints click the Simulation Settings command on the

Dynamic Simulation tab >Manage panel and then in the dialog box click (check) the Automatically

Convert Constraints to Standard Joints option and then OK.

4. The Dynamic Simulation dialog box will appear, telling you that the mechanism is over-

constrained by 1 degree as shown in the previous image. This means that that there is one

conflict. Click OK to close the dialog box.

5. In the browser notice the symbol. This tells us where the conflict exists. Expand the Standard

Joints node and then expand Cylindrical:1… and click Mate:13.

6. The Mate (line-line) constraint in the center of the cylinder is highlighted. This gives you place to

investigate the redundancy.

7. Exit the Dynamic Simulation environment by clicking the Finish Dynamic Simulation command on

the Dynamic Simulation tab > Exit panel.

Note: You can delete and edit assembly constraints in the Dynamic Simulation environment, or

exit the environment and make the changes in the assembly environment.

8. In the browser expand the Cyl_Bucket_foot_Deeper_Rod:1 and click on Mate:8 and then

Mate:13. These two Mate (line-line) command intersect and are causing the redundancy.

Note: To solve the redundancy you will delete a Mate (line-line) constraint and replace it with a

Mate (point-point) constraint. A Mate (line-line constraint maintains 2 degrees of mobility and the

Mate (point-point) maintains 3 degree of mobility. When the two constraints are converted to

joints there will be 1 degree of mobility where the cylinder is connected to the cylinder bucket foot.

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9. In the browser right-click on Mate:8, and click Delete from the menu.

10. Move the end of the cylinder rod away from the assembly.

11. Next you apply an assembly constraint. Follow these steps.

a. Click the Constrain command from the Assemble tab > Component panel.

b. In the graphics window select the circular edge of the Compensator:1 (yellow part) and

then the circular edge of the hole on the Cyl_Bucket_foot_Deeper_Rod:1 (grey part).

c. Click OK.

Note: In the optional exercise you learn how to simplify the cylinder that will remove the

redundant joint and place the joint in the middle of the shaft.

12. Enter the Dynamic Simulation environment by clicking the Dynamic Simulation command on the

Environment tab > Begin panel.

13. You notice there was no redundancy message and the symbol has been removed.

14. Save the file.

Simulation

1. If you successfully completed the last section, you can continue working on the same file. If you

were not able to complete the previous section, open the file.\Boom Arm\Boom Arm Assembly -

Constraint Fixed.iam.

2. If needed, enter the Dynamic Simulation environment by clicking Environment tab > Begin panel

> Dynamic Simulation.

3. Define gravity by expanding the External Loads node in the browser and then double-clicking on

the Gravity node and then do the following:

a. Uncheck the Suppress option

b. Click the Entity Selection button and then select the top surface of the Arm.

c. Reverse the direction of gravity by clicking the Flip Direction button.

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d. Click OK

4. Run the simulation by clicking the Play button in the Simulation Player dialog box. The bucket

swings down and through the Arm and through the cylinder.

5. Set the simulation to its beginning position, by clicking the Rewind button in the Simulation Player

dialog box.

6. Next you define the time in which the length of the stroke of the cylinder. To make this change

you need to be in the construction mode, in the Simulation Player click the Construction Mode

button.

7. In the browser, under the Standard Joints node, double-click on Cylindrical:1(Cy_Bucket_…

8. Click the dof 2 (T) tab. The (T) tells you that this is a translational degree of freedom. The Edit

initial conditions button should be current as shown in the following image on the left. Set the

current position to zero, by right-clicking in the Position cell and click Set offset as shown in the

following image on the right. This change does not affect the assembly constraint offset value; it

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just gives you an easy way to set a distance based on the current position.

9. Click the Edit imposed motion button.

10. In the Cylindrical:1(Cyl_Bucket_foot… dialog box do the following.

a. Click (check) the Enable imposed motion option

b. Click the Position radio button

c. Click in the Value area

11. Next you set the time and distance the cylinder will travel within this time. In the Imposed Motion

dialog box do the following.

a. Change the starting point for the X1 = 0 s and Y1 = 0 mm

b. Change the Ending point for the X2 = 3 s and Y2 = -750 mm

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c. Click the OK to close the Imposed Motion dialog box.

12. Click OK to close the Cylindrical:1 dialog box.

13. Run the simulation by clicking the Play button in the Simulation Player dialog box.

14. Open the Output Grapher by clicking the Output Grapher command on the Dynamic Simulation

tab > Results panel.

15. In the left side of the Output Grapher dialog box expand Standard Joints > Cylindrical:1>Driving

Force and click (check) the U_imposed[2] option.

16. In the graph area of Output Grapher dialog box, review the results of the imposed force.

17. Set the simulation to its beginning position, by clicking the Rewind button in the Simulation Player

dialog box.

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18. Next you apply a force to the bucket. To add this force, you need to be in the construction mode,

in the Simulation Player click the Construction Mode button.

19. Change the viewpoint so you can see the teeth like what is shown in the following image on the

left. And then click the Force command on the Dynamic Simulation tab > Load panel, and then do

the following.

a. Define the location of the force by clicking an endpoint on the middle tooth

b. Define the direction of one of the long vertical edges on one of the teeth.

c. In the Force dialog box change the Magnitude to 500 lbforce, it will automatically be

converted to Newtons.

NOTE: You can also enter the value in Newtons or metric units.

d. Reverse the direction of the force to it is point toward the inside of the bucket by clicking

the Direction button.

e. To keep the force parallel to the selected edge, though the range of motion, click the

Associative Load Direction option.

f. Click the OK button.

20. Run the simulation by clicking the Play button in the Simulation Player dialog box.

21. In the Output Grapher dialog box, review the imposed force.

22. Save and close the file.

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Optional Exercise

Simplified Cylinder with Two Lines In the last exercise you fixed a redundant issue between two conflicting assembly constraints. You can

simplify the geometry by using lines to represent components such as cylinders.

1. Open the file .\Boom Arm\Boom Arm Assembly - Cyl - Two Lines.iam.

2. To save time, this assembly has a level of detail that will suppress the existing cylinder with two

lines. In the browser expand the Level of Detail node and then double-click on Cylinder - Two

Lines.

3. In the browser expand Cyl Line:1 and Cyl Line:2 and investigate the assembly constraints that

were created. Click and drag on the bucket, notice how the bucket responds the same as when

the full cylinder was used.

4. Use what you learned in the first two exercises to create a simulation of this assembly.

a. Convert assembly constraints to joints

b. Setup gravity

c. Apply an imposed motion of 750 mm to Cylindrical:2 (Cyl Line:1, Cyl Line: 2)

d. A force of your choosing

5. Review the results.

6. When done, close the file and do not save the changes.

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References

The original Trebuchet assembly was created by John Helfen of Autodesk Inc.

View a video of the simulation of the Trebuchet created by John Helfen

at:http://www.youtube.com/playlist?list=PL1E99F2E1549EBEC7&feature=plcp

The original Boom Arm assembly was created by Saso Janjevski and can be downloaded from:

http://grabcad.com/library/case-cx350b

Additional Resources

Learn more about simulation from Autodesk Simulation Workshop

www.autodesk.com/simulationworkshop

Autodesk SIM Squad: Autodesk team of simulation experts who speak the language of CFD, FEA,

and all things mechanical and plastic injection molding

simulation.http://usa.autodesk.com/adsk/servlet/pc/index?id=16661243&siteID=123112

Additional videos from John Helfen: www.youtube.com/johnhelfen

Up and Running with Autodesk Inventor Professional 2013 : Part 1 Stress and Frame

Analysis

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Up and Running with Autodesk Inventor Professional 2013 : Part2 Dynamic

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