Determination of the post-critical state of compressed plates within the bi-nonlineary theory

In a majority of strength problems related to sandwich structures the concept of the linear displacement state is used. This state of displacements is defined with the help of the broken line hypothesis, which is used for the determination of critical states within the geometrically linear theory and for analysis of post-critical states of geometrically non-linear theory.

In the paper, taking into account the non-linear displacement state of the core and the geometrically linear theory for faces and core (binonlinear theory), we carry out an analysis of post-critical loads. The problem is solved by means of the energy method. The post-critical stresses are described by a general formula applied also for a uni-axial compressed plate simply supported at both edges.