Issues of Direct Application of Fracture Toughness Determination Procedures to Coupled Composite Laminates

摘要

The article presents examples of difficulties related to direct application of the standardized DCB and ENF test methods to composite laminates with mechanical couplings. It reveals delamination as one of the most common damage forms in the considered group of engineering materials. The paper is a part of the study presented in detail in other papers published elsewhere [2-4,11]. The Finite Element Method simulations of the interlaminar cleavage formation and growth prior to the physical experiments is shown as necessary. The advantages of the numerical methods of delamination modeling, such as the virtual crack closure technique in planning the experiments and introducing essential modifications in data reduction schemes are presented. The presence of unexpected mode-mixity in the standard fracture-toughness tests applied to the mechanically coupled composite laminates is also shown.