Mechanical performance and damage behavior of delaminated composite laminates subject to different modes of loading

This work focuses on the effects of delamination defects on the performance of laminated composites under different modes of loading. Based on the cohesive zone method, the finite element models are developed to investigate the mechanical performance and the damage behavior of laminated composites subjected to tensile and compressive load. Under compressive load, the load-bearing performance of laminates and bolted single-lap composite joints with delamination decreased by 31.9% and 13.7%, pre-embedded delamination laminates experience five main damage stages, and the failure mode of bolted single-lap composite joints with delamination defects is that damage occurs from the delamination position. On the contrary, the existence of delamination defects in a small area does not affect the tensile load-bearing performance and damage behavior of the specimens. Comparing the analysis results of finite element models with the experiments, the finite element models predict that the maximum load-bearing errors of laminate with delamination defects and bolted single-lap composite structure with delamination defects are within 5%. According to this analysis, it is found that the existence of delamination defects significantly decreases the load-bearing performance of laminated composites under a compressive load and changes the damage behavior.