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klusaebaja
Bolt Sorter Joined: Jul/09/2011 Status: Offline Points: 11 |
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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
Organizer Joined: Jun/16/2010 Location: U Laval Status: Offline Points: 256 |
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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.
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Nicholas Lefebvre
Universite Laval |
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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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.
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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Rob71zilla
Welding Master Joined: Feb/09/2009 Location: Utica, NY Status: Offline Points: 324 |
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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.
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Robbie
Former Team Captain SUNY Institute of Technology Current Engineer for Remington Arms A Redline a day keeps the carbon away. |
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OctoberSky
Welding Master Joined: May/20/2009 Location: Los Angeles Status: Offline Points: 123 |
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*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
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UCLA Racing
2010-2012 Captain "we'll never win mini baja" -Cheddar |
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p.lewis
Welding Master Joined: Oct/05/2009 Location: Greater Detroit Status: Offline Points: 296 |
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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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University of Rochester Alum
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OctoberSky
Welding Master Joined: May/20/2009 Location: Los Angeles Status: Offline Points: 123 |
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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 |
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UCLA Racing
2010-2012 Captain "we'll never win mini baja" -Cheddar |
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