A rational and efficient local stress recovery method for composite laminates

Abstract

Common stress recovery methods usually cannot introduce the stress boundary conditions. The general mixed finite element method can only solve the whole model and its calculation requires large memory resources. A stress recovery method using generalized mixed elements in a local model is proposed in this paper. The elements surrounding some nodes where stress results are required are selected to construct a local noncompatible generalized mixed element model, which is used to introduce the stress boundary conditions in the local model. For the problem of composite structures, the modified generalized mixed variational principle is used to obtain the solution equation of out-plane stress, and then the local models for the linear system of in-plane stress are constructed according to different material layers. The continuous results of in-plane stress in each layer of material can be obtained, and the discontinuity of in-plane stress at the interface of each material layer is ensured at the same time. Numerical examples show that this method can obtain objective and more accurate stress results. Compared with the mixed finite element method for whole model, the present method greatly improves the computational efficiency.