Strong and weak form

[oesa28337]

Hello,
I have a question about strong and weak form. We use weak form in FEM as it contains only first derivative of the displacement function, so we can use displacement functions with C⁰ continuity. This can help reducing the computation time. However, strain (and in turn stress) should be C^-1 continuous. Does that mean that we get discontinuities in the stress and strain solutions? This is contrary to my observation of any FEA of stress field, which seems to be continuous. Also, in FEM displacement functions, what if, if I use a quadratic polynomial? Does it mean that now I have C² continuous shape function?
Any comments, very welcome.

 

[JStephen]

There is a FEA subforum, perhaps check there:

http://www.eng-tips.com/threadminder.cfm?pid=727

 

[KootK]

My understanding is that FEM results are only accurate at the nodes. Everything in between is a continuous approximation of some sort.

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