Dual failure analysis of 3D structures under cyclic loads using bFS-FEM based numerical approaches

Failure mechanism of 3D structures cannot always be produced by the low-order finite elements due to the so-called volumetric locking effect. In this paper, dual numerical approaches based on the bubble face-based smoothed finite element method (bFS-FEM) are developed, ensuring that the locking problem is prevented and accurate load factors of elastic-perfectly plastic structures under cyclic actions are achieved. The failure mechanisms, in terms of plastic dissipation, are realized as incremental or alternative plastic failure modes, enabling different treatments in engineering practices. Moreover, the pseudo-static approach is capable of providing three-dimensional stress fields at the failure state, which is crucial for structural design. Interaction diagrams associated with various load-types and-ranges are illustrated in numerical experiments, showing that the bearing capacity envelopes of structures under cyclic loads are evidently smaller than that of proportional loads.