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FEA Von Mises vs Principal Stress Awesome
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Posted by: promech

04/08/2005, 13:31:55

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I have done an FEA analysis where the results indicate that the max principal stress is significantly higher than the von mises stress (700 ksi vs 1100 ksi). The material is hardened tool steel. Does this sound normal? I usually get results that are reasonably close for most analyses.






Modified by Administrator at Sat, Sep 09, 2006, 09:12:34


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Re: FEA Von Mises vs Principal Stress
: FEA Von Mises vs Principal Stress -- promech Post Reply Top of thread Engineering Forum
Posted by: swearingen

04/11/2005, 08:20:07

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You can have cases where the principal stresses are much higher than your von mises stresses. For instance, if you have near equal compression stresses in the prinicpal axes, the von mises stresses will be very low. Of course, if you have all equal compressive (or tensile) stresses, there is NO von mises stress...







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Re: FEA Von Mises vs Principal Stress
: Re: FEA Von Mises vs Principal Stress -- swearingen Post Reply Top of thread Engineering Forum
Posted by: promech

04/11/2005, 08:45:12

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I see. Shape vs volume, right? In either case, which criterion should I use? It sounds like I should use max principal (even though the material is ductile).

I stated my question in reverse. My von Mises stress is 1100 ksi, max principal is 700 ksi. I always thought that max principal is usually slightly higher.







Modified by promech at Mon, Apr 11, 2005, 09:42:48


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Re: FEA Von Mises vs Principal Stress
: Re: FEA Von Mises vs Principal Stress -- promech Post Reply Top of thread Engineering Forum
Posted by: swearingen

04/11/2005, 17:43:12

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The only way you can get von mises stresses greater than a max principal stress is when one or both of the other stresses is negative (compressive).







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: Re: FEA Von Mises
: Re: FEA Von Mises vs Principal Stress -- swearingen Post Reply Top of thread Engineering Forum
Posted by: Engineer fahim

01/17/2010, 08:41:04

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Sir,
I am using coventorware software for FEA analysis and i in my structure a part is behaving like a contilever beam ,a force of 300uN is applied at the tip of cantilever while other end of beam is fixed , it give me should give me tensile stesses at upper part and compressive at bottom side but it is giving me all tensile stresses at both side these are Von-mises stresses ,anybody who can give the reason for this kindly advise me?







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