Inventor General Discussion

## Inventor General Discussion

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Posts: 206
Registered: ‎12-12-2003
Message 1 of 8 (1,138 Views)

# Autodesk Inventor Dynamic Simulation

1138 Views, 7 Replies
12-20-2013 08:23 AM

I am new to Inventor 2014 Dynamic Simulation and would greatly appreciate more detailed information on making joints than can be found in the tutorials.  This is one fantastic tool and I would like to learn to use it.

I do have a specific question. I made a simple simulation of a freely falling cylinder with rounded nose falling onto a transverse fixed cylinder using a 2d contact joint. The simulation showed the falling cylinder make contact and bounce back as it should. The output grapher showed the forces generated at contact on each bounce. I did some fairly simple physics calculations to see if my calculated forces were in the same ballpart as the dynamic simulation forces and they were within reason. When I changed material on the falling cylinder from steel to rubber the contact forces dropped. However, when I changed material on the stationary cylinder from steel to rubber, the contact forces did not change. Can anyone tell me the procedure used in dynamic simulation to generate these contact forces. Thanks for the help. Phil

Changing the Material wont help

Change restitution co-efficient properties in 2d contact will help to some extent

The coefficient of restitution (COR) of two colliding objects is a positive real number between 0.0 and 1.0
representing the ratio of speeds after and before an impact, taken along the line of the impact. Pairs of objects
with COR = 1 collide elastically, while objects with COR < 1 collide inelastically.

For a COR = 0, the objects effectively "stop" at the collision, not bouncing at all. An object (singular) is often described as having a coefficient of restitution as if it were an intrinsic property without reference to a second object, in this case the definition is assumed to be with respect to collisions with a perfectly rigid and elastic object. The Coefficient of Restitution is equal to the Relative Speed After Collision divided by the Relative Speed Before Collision

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Message 2 of 8 (1,135 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-20-2013 08:25 AM in reply to: pquenzi

Get the Wasim Younis Book 2 from Amazon.com

This was an interesting assembly posted yesterday

http://forums.autodesk.com/t5/Inventor-General/Dynamic-Simulation-Parameters/td-p/4702905

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Message 3 of 8 (1,124 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-20-2013 08:50 AM in reply to: JDMather

JDMather wrote:

Get the Wasim Younis Book 2 from Amazon.com

This was an interesting assembly posted yesterday

http://forums.autodesk.com/t5/Inventor-General/Dynamic-Simulation-Parameters/td-p/4702905

100% concur.

Wasim Younis' book is the gold standard when it comes to dynamic simulation.  There's probably nobody on earth who isn't employed by Autodesk that knows more - and can teach more - about how to use Inventor's simulation products.

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Posts: 206
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Message 4 of 8 (1,123 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-20-2013 08:51 AM in reply to: JDMather
Okay, I ordered it. Still would appreciate any explanation on this post if possible. Thanks. Phil
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Message 5 of 8 (1,113 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-20-2013 09:13 AM in reply to: pquenzi

pquenzi wrote:
... Still would appreciate any explanation on this post if possible.
...

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Autodesk Inventor 2015 Certified Professional
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Message 6 of 8 (1,103 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-20-2013 09:54 AM in reply to: pquenzi

Here are the files.

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Posts: 311
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Message 7 of 8 (1,066 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-23-2013 09:07 AM in reply to: pquenzi

Changing the Material wont help

Change restitution co-efficient properties in 2d contact will help to some extent

The coefficient of restitution (COR) of two colliding objects is a positive real number between 0.0 and 1.0
representing the ratio of speeds after and before an impact, taken along the line of the impact. Pairs of objects
with COR = 1 collide elastically, while objects with COR < 1 collide inelastically.

For a COR = 0, the objects effectively "stop" at the collision, not bouncing at all. An object (singular) is often described as having a coefficient of restitution as if it were an intrinsic property without reference to a second object, in this case the definition is assumed to be with respect to collisions with a perfectly rigid and elastic object. The Coefficient of Restitution is equal to the Relative Speed After Collision divided by the Relative Speed Before Collision

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Ravi Kumar MB,
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Message 8 of 8 (1,049 Views)

# Re: Autodesk Inventor Dynamic Simulation

12-23-2013 01:15 PM in reply to: pquenzi

Thank you. I did play with the coefficient of restitution a little and I see how it works. Your comment about the second body being assumed perfectly elastic is basically what I was interested in. As long as I know what the assumptions are I'm good for now. Phil

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