Descriptive relationships between bearing response and macroscopic damage in GRP bolted joints

The aim of this investigation was to examine the relationships between laminate architecture, macroscopic damage and important bearing response characteristics such as damage load, ultimate failure load and post-failure behaviour in general purpose glass-fibre reinforced polyesters. Six representative laminates with varying 0° roving, 90° roving and chopped strand mat contents were tested for their bearing response in a single-bolt double shear lap configuration. Three specimen configurations were tested. The first specimen geometry was the standard coupon geometry of the ASTM D5961 bearing response test with a pitch distance ratio ‘w/D’ of 6 and an end distance ratio ‘e/D’ of 3. The second and third geometries used a ‘w/D=6, e/D=6’ and ‘w/D=2, e/D=3’. The diversity in laminating sequences and geometries led to equally diverse failure patterns. However, interesting general trends were observed that went beyond this diversity, thereby creating a global picture of failure in GRP bolted joints.