Chassis FEA Help

[scott_rfr]

So I have searched the forums and done my homework but I am still having some trouble with our chassis fea. I am currently using solidworks to model the chassis and ansys to do the fea.
I have been able to create simple beams in ansys and do the analysis (using the create geometry feature). My problem is bringing in the chassis into ansys. I have tried saving as an iges then importing to ansys. However I am not sure how to efficiently define nodes so that I can apply the beam elements. I can get the iges file in but how exactly do I define my nodes from here without manually creating nodes by inputing xyz location for every point on the chassis.

Thank you,
Scott Mingay
Rutgers FSAE

[scott_rfr]

So I have searched the forums and done my homework but I am still having some trouble with our chassis fea. I am currently using solidworks to model the chassis and ansys to do the fea.
I have been able to create simple beams in ansys and do the analysis (using the create geometry feature). My problem is bringing in the chassis into ansys. I have tried saving as an iges then importing to ansys. However I am not sure how to efficiently define nodes so that I can apply the beam elements. I can get the iges file in but how exactly do I define my nodes from here without manually creating nodes by inputing xyz location for every point on the chassis.

Thank you,
Scott Mingay
Rutgers FSAE

[Drew Price]

Without any prior experience doing this, can you import an *.iges from SW with just the nodes, and use the geometry builder to just insert the beams with the desired geometry in the right places? We had enough bad luck trying to get an *.iges into Ansys correctly that we just gave up and used Cosmos.

Best,
Drew

[billywight]

How is your chassis modeled? If you made it as a bunch of sweeps or weldment members, you can hide all the solid bodies, show all the sketches (sweep paths, etc) so only a wireframe is visible. Then create a 3D sketchand convert all the entities of the various sketches shown so the 3D sketch is now a wireframe of the chassis. Hide everything except for the 3D sketch. File, save as IGES, options and select IGES wireframe and export sketch entities. You should end up with an IGES wireframe of the chassis that will import into Ansys.

[scott_rfr]

I have the wire frame in Ansys. I already have a "cleaned up" wire frame of the chassis just contains the sketches ententes. So I have a bunch of lines and key points in ansys however I am having trouble creating nodes and beam elements from there.

Scott

[Mike Macie]

I think it would be easier/faster just to recreate your chassis in ansys instead of trying to figure this out. Just write down all your node locations from solidworks, enter them as keypoints in ansys, connect the points with lines, and define your elements.

Also the 07 and 08 version of Cosmos can do beam element analysis if you have it. The 07 version can only do straight members and the 08 version can do curved members. It's easy to set up and run if you want to compare results

[scott_rfr]

I would use cosmos however we are having a lot of licensing trouble with getting cosmos running. In the meantime I was trying to create an ansys model.

Scott

[L B0MB]

I briefly tried using ANSYS but it really is a lot of effort for running heaps of chassis FEA's

I modelled in SolidWorks and used COSMOS to perform the FEA directly on the SW models

In SW2007 you can use beam elements for a tubular chassis (straight sections of pipe only) which allows quick FEA's at around 30 seconds once the FEA environment has been created

I created line sketches and added tube with the weldment function. The material properties are then added in COSMOS

This was a very quick method of chassis analysis which was good as I did around 50 iterations of pipe location and sizing

None of this helps you with ANSYS tho...

[Chris Lane]

Hey Lewis,

Go and talk to the guys at Leap Australia in Perth. They are resellers of Ansys and run training courses there. Our chassis designer and I went to a 3 day introductory course for Ansys FEA. Highly worth it. The training dude Sam Nardella, really knows his stuff and is also a motorsport fan.

If you're serious about ANSYS, then doing this course saves you SO MUCH time fiddling with it.

[L B0MB]

Hi Chris

Thanks for the info but it was Scott Mingay from
Rutgers FSAE who was after the help with ANSYS

COSMOS was fine for what I was trying to achieve

Anyone else with ANSYS know-how?

[AJS]

We have developed a pretty nice text file that allows us to do multiple runs in ANSYS in a short amount of time. I've done well over 40 runs on it already. We can't quite figure out how to make each line a different tube thickness yet without going through the model in ANSYS and meshing them all separately. It works well for what we do though.

[benjo]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AJS:
We have developed a pretty nice text file that allows us to do multiple runs in ANSYS in a short amount of time. I've done well over 40 runs on it already. We can't quite figure out how to make each line a different tube thickness yet without going through the model in ANSYS and meshing them all separately. It works well for what we do though. </div></BLOCKQUOTE>

Can't you just break it up, so you for example:

real,1
lmesh,1,10,1 (lines 1:10 @ 1 line interval)
real,2
lmesh,11,30,1

Something like that anyway.

Then just go into solu and post process as you normally would.