Evaluation of the Perturbation Sensitivity of Composite Laminated Shells

Imperfection sensitivity and its influence on the limit loads of shells are widely discussed phenomena. Both phenomena may be classified with respect to the type of imperfection, which may be generalized to a perturbation. As perturbations influence the stability of shells, the identification of unfavorable perturbations is essential for the design of shells. The perturbation energy concept enables one to identify unfavorable perturbations of different kinds and to evaluate the sensitivity of fundamental states against buckling by the perturbation energy. This paper discusses the perturbation sensitivity of unstiffened composite laminated cylindrical shells consisting of unidirectional layers. Moreover, an approach for a load-level-specific modification of the perturbation sensitivity is introduced.