Physics, Dynamics simulation 4

[rlee53]

I'm looking for a software to simulate the interaction of machinery and objects, similar to what can be done with Working Model 2D and Dynamic designer. It needs to model contact and friction, gravity, etc. What else is out there? I will only need it occasionally, so I can't justify several thousand dollars. I'm looking for lower cost software.

 

[GregLocock]

FreeCAD

http://www.dmoz.org/Science/Software/Simulation/

and

http://www.dmoz.org/Computers/Robotics/Software/Simulation/

modelica

Sadly none will match Working model I suspect. If you do find anything good let us know.


Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[PSE]

You could try looking/searching through this site as well. A quick search using physics simulation yielded over 1600 responses so you might want to drill carefully.

http://sourceforge.net/

Regards,

 

[49again]

Do a Google search on "sketchyphysics"

 

[rlee53]

Thanks for the replies. In the meantime I came across several other free sources.

I'm testing one called "Newton Playground" that works fairly well for creating an animation/visualization.

The sketchphysics from google looks similar; I'll give it a try also. I think my CAD software even has an add-on that will output to sketchup; so that may be convenient.

In my search I came across a lot of physics simulators and libraries used in computer game and entertainment applications. Some very sophisticated.

 

[namdac]

What CAD platform are you using? Most of todays cad software does simulations in 3-D. You might get by with a third party ad-on, but check to be sure you do not have the ability already. Yet, are not aware of it's existance within the program structure.
Regards,
Namdac

 

[GregLocock]

Full physics simulators including contacts and friction? Really, can you give an example?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[rlee53]

I believe Greg is correct.

What I was looking for is to model free body collisions.
My software, Alibre, only does motion simulations with kinematics. I cannot model physics with contact and friction among free, unconstrianed bodies, only kinematics with things like linkages.

The last time I used Solidworks or Pro/E, I don't think either could do physics, however mechanica did do a pretty good job with contact between cams, including liftoff of the roller from the cam surface.

 

[pdybeck]

SolidWorks 2008 with physical simulation...

http://www.solidworks.com/pages/onl...sical_simulation/d36_physical_simulation.html

In addition SolidWorks Office Premium uses software from MSC (CosmosMotion - which uses the ADAMS) that is able to solve physics based simulations including considerations for contact and friction. It picks up where the simluation leaves off in the core SolidWorks program. Reaction forces can be exported to CosmosWorks FEA for a static study of stress/strain.

 

[pdybeck]

sorry... - which uses the ADAMS software engine....

 

[pdybeck]

Here is a quick demo of Cosmos Motion in SolidWorks...

http://www.solidworks.com/pages/onl.../d51_motion_analysis/d51_motion_analysis.html

 

[rlee53]

Thanks pdybeck. The bowling simulation is much closer to the type of simulation that I'm interested in; do you know exactly what level of solidworks is used; the basic package, Office, or Office Premium, or other, etc?

Approximately what is the current list price for that particular package? I had quotes for 2007 last year, but at the time did not have any justification to buy.

 

[pdybeck]

I am pretty sure the base package would be able to accomplish the bowling simulation - plain old SolidWorks.

 

[IRstuff]

seems to be something funny about those bowling pins. They're not behaving the way I would expect.

TTFN

FAQ731-376

 

[rlee53]

I noticed that too. The pins seem to move in a clump initially, rather than bouncing around the way I would expect in reality. Are the material properties settings perhaps WAY off, or is it not modelling physics very well, or is the demo not what is implied by the video?

 

[pdybeck]

Yes,

Friction is not simulated under the core program in physical simulations. You would need the CosmosMotion portion of the software to simulate friction, and then it would look and behave correctly. The easiest way to get CosmosMotion is to purchase SolidWorks Office Premium. CosmosMotion uses the ADAMs software engine, while physical simulation in the core program uses the PhysX™ software engine by AGEIA. Upon installing 2008, the AGEIA software engine is installed.

 

[pdybeck]

I should also mention that in CosmosMotion you have control over the elastic properties of the bodies as they contact. You can set the impact and coefficient of restitution properties for bodies. You are not seeing this under physical simulation with the AGEIA engine. I'm not sure if the AGEIA engine can do this kind of thing, or whether its been disabled for SolidWorks. In CosmosMotion friction and elastic propeties are applied according to default materials to bodies in contact. You can change materials and also tweak the values to whatever you need. The time to solve the motion simulation with 3D contact enabled in CosmosMotion will increase due to the frictional and impact calculations being performed that are not considered under the core phyiscal simulation by AGIEA.