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Simulation Study Constantly Failing

Simulation Study Constantly Failing

Simulation Study Constantly Failing

(OP)
I am trying to model and optimize a piece of climbing equipment called a 'cam', but am struggling to get an accurately restrained study to solve.

I have been able to do so by fixing a few small faces near where the points of contact would be, but that is not very accurate as the restrained faces actually strengthen the assembly.

The more accurate method it to use 2 parallel walls with defined contact to the cam lobes. I have tried this as many ways as I can think: no penetration (with specified friction), penetration, bonded, shrink fit, with and without large displacement flagged, with the walls 'fixed' completely, with them as a set material and only the outer face as fixed geometry.

Most of my effort has gone into a static study, but I have even tried it as a non-linear to help ramp the main force in smoothly, since the frictional force is a function of it. No go. I get failures ranging from a 'study failed' to 'incremental elastic strain too large', and other vague failures.

Basically, in real life, a spring preloads the lobes into the wall. the main axle pivot sits above the plane made by the lobe contact points (at the camming angle). As downward force is applied to the main stem, more force is redirected outwards into the walls, generating more frictional force and eventually bending the lobes and axle. I have tried using defined friction (between the lobes and wall) from .4 up to 1. I have preloaded the lobes with force on a particular set of faces nearly parallel to the walls, and also as a torque on the lobes.

What am I missing here guys? Are the study types I am using not suited for this situation?

Any help would be GREATLY appreciated! I'm sure you know how much time you can burn up waiting hours only to come back to a failed study!



 

RE: Simulation Study Constantly Failing

(OP)
I'm trying a slightly different now. I went back to a static study. Used collision detection to position my test walls (for some reason it will not let me use a coincidence mate between the wall and cam lobe). I then inserted a plane on each side using the test wall face and hid the walls. I then chose a virtual wall contact set between the lobes and the planes and added friction. For some reason, after clicking okay to the virtual wall contact set, it doesn't appear in the contact list. Any ideas?

RE: Simulation Study Constantly Failing

Can you post your model or a simplified version?

Rob Stupplebeen

RE: Simulation Study Constantly Failing

(OP)
What are you looking for exactly? The assembly and all individual components? This model is about as simplistic as I can make it... I was just hoping that I could get some guidance on what type of study, settings, constraints, contacts, etc from those with experience.

The major issue seems to be using the smooth curved cam lobe contacting the wall face to restrain the assembly and redirect force using friction.

RE: Simulation Study Constantly Failing

(OP)
Anyone?

RE: Simulation Study Constantly Failing

Do a plane model in Cosmos/M. It will run faster and be easier to troubleshoot.

TOP
CSWP, BSSE
www.engtran.com  www.niswug.org

"Node news is good news."

RE: Simulation Study Constantly Failing

(OP)
Can you give me a brief explanation on how to do that?

RE: Simulation Study Constantly Failing

Do you have Geostar installed? That is the pre/post processor for Cosmos/M. I think it still comes with Simulation.

TOP
CSWP, BSSE
www.engtran.com  www.niswug.org

"Node news is good news."

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