Interfacial crack growth of delaminated composite laminates under hygrothermal environment

The laminated composite structures in harsh hygrothermal environment are easy to undergo premature buckling and delamination propagation. This paper proposes a theoretical study on the nonlinear buckling and interfacial crack propagation of thick plate containing delamination by considering the hygrothermal effect and the contact effect. Based on the variational principles of variable boundary, the total potential energy of the laminates subjected to hygro-thermal-mechanical loading is established from which the governing equations for nonlinear post-buckling and the expression of energy release rate for delamination propagation are derived. The post-buckling equilibrium paths of the laminates characterized by the in-plane load vs deflection amplitude curves are determined via perturbation technique and Galerkin approach. With the available solutions from post-buckling analysis, the theoretical solution of threshold load corresponding to the delamination propagation is determined according to Griffith fracture criterion. By developing MATLAB program, numerical calculations are performed to discuss the effect of the temperature, the hygroscopic concentration and the delamination conditions on the buckling and delamination propagation threshold load. The solutions are compared with the results from ABAQUS finite element analysis and the predictions obtained from classical laminated plate theory, both showing good agreements with the presented theoretical solutions. Results show that hygrothermal environment reduce the buckling load and the delamination propagation threshold load. Besides, neglecting the transverse shear strain may overestimate the load-carrying capacity of the laminates. © 2022 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.