Postbuckling of composite laminates under compressive load and temperature

Abstract

Here we study the thermo-mechanical postbuckling response of fibrous composite laminates. This study is based on the Natural Mode Method and invokes rigid-body and straining modes of deformation that are assigned to the edges of flat and shallow shell laminated triangular finite elements. Some new ideas on the subject are introduced and implemented in the conceived nonlinear algorithm, most notably the incorporation of temperature-dependent material properties (cubic variation), the decomposition of the total strain energy into its invariant natural components, assessing also their effect on failure initiation, the combined effect of load and temperature and the influence of initial imperfections on the overall behaviour, and finally comments on some of the intricate differences revealed for some problems by using the flat and shallow shell triangular elements. Comparisons with reported analytical and experimental results is attempted where available. Overall, the computational experiments substantiate the developed methodology and show its potential to treat larger and more complex panels and also contribute to their design.