Plastic collapse analysis of Mindlin–Reissner plates using a composite mixed finite element

The paper proposes a mixed finite element model and experiments its capability in the analysis of plastic collapse Mindlin–Reissner plates. The model is based on simple assumptions for the unknown fields, ensuring that it is easy to formulate and implement. A composite triangular mesh is assumed over the domain. Within each triangular element, the displacement field is described by a quadratic interpolation, while the stress field is represented by a piece-wise constant description by introducing a subdivision of the element into three triangular regions. The plastic collapse analysis is formulated as quadratic and conic mathematical programming problem and is accomplished by an interior-point algorithm, which furnishes both the collapse multiplier and the collapse mechanism. A series of numerical experiments shows that the proposed model performs well in plastic analysis, where it takes advantage of the absence of locking phenomena and the possibility of simply described discontinuities in the plastic deformation field within the element.