Static strength and damage evaluation of high speed drilled composite material using acoustic emission and finite element techniques

In this paper, a very promising procedure to evaluate damage initiation and propagation of high speed drilled composite laminates base on Acoustic Emission (AE) and Finite Element (FE) techniques is proposed. First, the extent of delamination after high speed drilling was measured in unidirectional and woven composite specimens under different feed rate and cutting speed parameters. Three point bending tests were then performed to investigate the effect of drilling-induced delamination on static strength and the damage mechanisms in the drilled specimens. FE simulation including Cohesive Zone Modeling (CZM) and an improved Continuum Damage Mechanics (CDM) approaches was conducted to predict damage initiation and propagation of each distinct damage. Besides, AE was also used to notice the damage emergence and investigate these damage mechanisms. The results showed that the effect of drilling parameters on static strength is insignificant, however the main accomplishment of this work is illustrating a good consistency between experimental procedure, exhaustive FEM and AE techniques. FEM and AE can be used as efficient ways to predict damage initiation and failure of composite structures and also to evaluate damage mechanisms in drilled composite materials with two kinds of lay-up. Consequently, it is feasible to understand the effect of lay-up on occurring different damage mechanisms.