THREE-DIMENSIONAL ELASTO-PLASTIC ANALYSIS OF THICK LAMINATED COMPOSITE PLATES USING HYBRID-INTERFACE ELEMENTS

摘要

A novel elasto-plastic material model for laminated composite plates has been developed and incorporated in 3D hybrid-interface-displacement finite element formulation. Incremental iterative scheme has been adopted to obtain inelastic response of laminated plates. Isotropic hardening and associated flow rule have been considered in development of plasticity theory. The material model accounts for different yield strengths of FRPC in tension and compression. The model has been generalized for anisotropic materials by introducing parameters of anisotropy. Normal shear interaction terms have been introduced in the yield function to have better agreement with experimental results. Parameters of anisotropy have been evaluated with reference to the shear strength instead of normal strength to account for nonlinear behaviour of lamina under shear. Proposed elasto-plastic formulation is the first of its kind to estimate anisotropy and hardening parameters with reference to shear strength and ensures realistic positive definite value of effective stress for all possible states of stress. Numerical examples have been presented to demonstrate the validity and effectiveness of the present formulation. Formulation has been applied to various numerical problems and the influence of ply-angle on elasto-plastic behavior of thick as well as thin laminate is discussed. The transverse shear strength of the laminae has been observed to significantly affect the load-deflection behavior of thick laminated plates.