Subcritical damage mechanisms of bolted joints in CFRP composite laminates

A detailed experimental programme is presented that was conducted in order to establish a data base for strength and subcritical damage mechanisms of bolted joints in CFRP composite laminates. Single fastener double-shear tensile tests for various joint geometries were performed for a range of cross-ply and quasi-isotropic lay-ups of HTS40/977-2 CFRP material system. Penetrant enhanced X-ray radiography was used to define the subcritical damage locations which are of great importance when modelling the failure response of the joints. It is suggested that the subcritical damage planes can be modelled using cohesive zone elements (CZEs) in order to develop physically based strength prediction methods for bolted joints in CFRP laminates.