Buckling/Plastic Collapse of Plates under Cyclic Loading

Abstract

To assess the load carrying capacity of a ship's hull under extreme longitudinal bending, it is very important to know the behaviour of individual structural members. In this connection, the behaviour not only under monotonously increasing load but also under cyclic load as well as during unloading and re-loading after buckling/plastic collapse has to be investigated into.
From this point of view, a series of elasto-plastic large deflection analysis is performed by the Finite Element Method on plates subjected to cyclic inplane load. The main conclusions obtained are :
(1) The inplane rigidity during unloading after buckling/plastic collapse converges upon a certain value with the increase in applied strain.
(2) The residual deflection, when unloaded after the compressive ultimate strength has been attained, increases with the increase in applied compressive strain, whereas the recovered deflection during unloading tends to become a constant.
(3) When extreme cyclic load is applied under constant strain amplitude, the stress-strain and stress-deflection relationships tend to converge to the respective certain loops after several cycles, but not completely converge.