Buckling Analysis Types

Figure 1: LUSAS Eigenvalue dialog

Most finite element packages will offer you two types of eigenvalue buckling analysis.

The linear analysis is much simpler, quicker to run, and adequate in most cases but does not correctly model any of the following situations:

The archetypal case where these effects are likely to be significant is in the analysis of a shallow arch, e.g. a Von Mises Truss.

The non-linear analysis works in all situations, but is much more complicated and more computationally expensive, as the analysis needs to use trial and error to extract eigenvalues at various different load factors to narrow down which ones give eigenvalues of zero.