Buckling and Postbuckling Analysis

[cptamerica]

Hello,

I'm pretty new to Abaqus, and I've been working on modeling buckling of a thermally loaded plate that is completely constrained on both ends. I've been using the Abaqus manual extensively along with other papers on the subject, but I still am unsure exactly what the results mean. If anyone could help me understand exactly what the eigenvalues mean (in the case of an applied temperature to a plate constrained on both ends with an assigned coefficient of thermal expansion), I would be very grateful. Also, I understand how to introduce an imperfection into a postbuckling analysis, but I do not understand what the postbuckling analysis actually does. The different approaches to postbuckling, such as regular static, damped static, Riks, or dynamic, are also confusing to me.

Thanks in advance

 

[uwcomposites]

Hello,

I am also unfortunately new to Abaqus, however, the resulting eigenvalues which you obtain from a FEM buckling analysis are the load factors. For instance, say you apply 1 Lbf/in compression to your plate, and the first eigenvalue is 10. That means that the predicted critical buckling load is 10 times higher than what you applied. The other eigenvalues are the critical bucking load for the higher buckling modes, which are instructive to look at, but generally your structure will go unstable at the lowest buckling mode. If you are applying thermal loading, the same concept applies, except I would think that a negative thermal gradient will result in compression and therefore buckling instability.

In general terms, at the onset of buckling, your structure will still have some load carrying capability (it's not game over yet). So understanding how much load you can still carry is what a post buckling analysis does. I will let someone with Abaqus experience answer you about the various approaches.

Best of luck to you