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klusaebaja View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote klusaebaja Quote  Post ReplyReply Direct Link To This Post Topic: A arms
    Posted: Aug/10/2011 at 4:15am
do a arms deform by buckling?? please let me know from your past experiences??
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Nick914 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nick914 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/10/2011 at 7:14am
If they are strong enough to resist bending, it should not be a problem.
You could also check with calculations, loadings are suggested on an other thread.
Nicholas Lefebvre

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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/10/2011 at 8:04am
If you do some simple thinking exercises and hand calculations you will find that Nick is right.  The only situation that could cause a control arm to buckle would be a turn or a little rubbing with another car.  If the arm buckled under that, it would bend with the car just sitting statically.
Kyle Collins
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Aug/10/2011 at 12:22pm
We have had ours buckle before but it was due to a barrel roll so that's an extreme circumstance that I would expect them to buckle under.
Robbie
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OctoberSky View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote OctoberSky Quote  Post ReplyReply Direct Link To This Post Posted: Aug/10/2011 at 11:33pm
*Baja shock-mounting a-arms don't buckle before bending.  I could definitely see a case in which, say, a front upper control arm (no shock mounted to it) could buckle, since they aren't ideally ever loaded in bending.  Then again, it could yield in compression first, depending on slenderness ratio, etc.  Think about you steering tie rod, it's sort of the same situation.  Again, you have to do the hand calc's, use the proper end conditions, etc. to be sure, but I probably wouldn't worry about it too much
UCLA Racing
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Post Options Post Options   Thanks (0) Thanks(0)   Quote p.lewis Quote  Post ReplyReply Direct Link To This Post Posted: Aug/11/2011 at 10:48am
All of our steering rods have buckled or broken a heim/clevis. We never crushed a steering rod because they're too long and the polar moment of inertia is small enough that the critical load for buckling is always smaller than crushing.
 
Use Nastran solution 105 for buckling. Hopefully that's available in Solidworks, Unigraphics, or whatever CAD/FEA software package you're using. Also, I think you might want to use a 1-D bar element model instead of 3-D solid elements for the buckling case to keep the analysis quick.
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OctoberSky View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote OctoberSky Quote  Post ReplyReply Direct Link To This Post Posted: Aug/11/2011 at 12:05pm
I haven't got around to trying buckling in Solidworks, but I use FEMAP (Nastran-based FEA) everyday at work, and for the 36.7 buckling analysis you can also control the scaling factors; usually from .01:5 is more than enough (I think default runs -10:10).  This should quarter your solve time; it only solves for positive eigenvalues.  

Edited by OctoberSky - Aug/11/2011 at 2:57pm
UCLA Racing
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