Damage characterization in composite laminates with holes

Erartsın, Ozan
The main objective of this study is to conduct progressive failure analysis (PFA) of quasi-isotropic open-hole tension coupons that exhibit different failure patterns, namely brittle, pull-out, and delamination failure. Effect of delamination, in-situ strengths and degradation trend on failure patterns and loads are also investigated. Explicit finite element method is used for the study. Intra-laminar regions in the finite element model were modeled with 3-D continuum shell elements and interlaminar regions were modeled with 3-D interface elements with bilinear tractionseparation formulation of Cohesive Zone Method (CZM). Hashin’s failure criterion is used along with linear gradual damage evolution for intra-laminar regions. Results are compared with the open-hole tension tests that are conducted and taken from the literature. The results show that the model developed here gives satisfactory results in modeling the damage progression in open-hole tension laminates where three different failure patterns are involved. It is also observed that the delamination plays an important role for the damage progression in openhole tension laminates; thus, neglecting it may result in inaccurate prediction of damage patterns and overestimated ultimate loads.