Experimental analysis of failures in filled hole compression tests of carbon/epoxy laminate

In this study, failure modes occurring during Filled hole compression (FHC) tests were analysed using post-mortem analysis for failure pattern identification and high-speed cameras for failure scenario (damage initiation and progress). Two different failure scenario were experienced depending upon the stacking sequence: ∗ Net compression failure for high 0° oriented lay-ups. The crack initiation is observed near the bolt but the location differs with bolt tightening or not, enabling future validation of finite element models. ∗ Off-set compression failure for low oriented lay-ups. This failure mode was attributed to bearing by-pass loads in the literature. Nevertheless, this study demonstrates that a different scenario can occur linked to a specimen effect: first a delamination appears at the free edges of the specimens. Then, as the delamination area grows, a local buckling occurs creating a net failure at the tip of the wave. The results obtained in this study are the basis for developing more robust sizing methods for bolted joints based on physical understanding of failure mechanism and associated sensitivity parameters.