On the nonlinear analysis of shells with eigenmode-affine imperfections

Existing stability design rules for thin shell structures are generally concerned only with simple geometries and simple/uniform loading conditions. For more complex situations, nonlinear finite element analysis provides a powerful tool for assessing the buckling strength of shells. Since shells are generally sensitive to initial geometric imperfections, a reliable prediction of their buckling strength is possible only if the effect of geometric imperfections is accurately accounted for. A commonly adopted approach is to assume that the imperfection is in the form of the bifurcation buckling mode (eigenmode-affine imperfection) of a suitable magnitude. This paper discusses a number of issues in the nonlinear analysis of shells with eigenmode-affine imperfections.