Non-linear dynamic stability analysis of composite laminates under periodic in-plane compressive loads

This work deals with the investigation of the non-linear instability behaviour of the composite laminates subjected to periodic in-plane/axial load, through the "nite element formulation with dynamic response analysis. Here, C1 eight-noded shear-#exible plate element, based on a new kind of kinematics which allows to exactly ensure the continuity conditions for displacements and stresses at the interfaces between the layers of the laminate, and also the boundary conditions at the top and bottom surfaces of the laminate, is employed. The non-linear governing equations obtained are solved using the Newmark direct integration method coupled with a modi"ed Newton}Raphson iteration procedure. The analysis brings out various characteristic features of the dynamic stability such as existence of beats, their dependency on the forcing frequency, and the typical character of vibrations in the di!erent regions. Numerical results are also presented to highlight the in#uence of ply-angle and lay-up of the laminate on dynamic stability behaviour of the composite laminates.