Bearing performance improvement of single-lap, single-bolt basalt composite joints by locally strengthening the joint location using carbon fibre

Abstract

The effect of local thickening with similar and different reinforcement materials for single-lap, single-bolt basalt composite joints was investigated. A vacuum-assisted resin transfer moulding technique was used to fabricate three types of test configurations, namely the reference basalt joint, the localised thickened joint using basalt fibre, and the localised thickened joint using the carbon fibre, i.e., localised carbon fibre hybridisation in sandwich-like and non-sandwich like manner. These configurations were tested under tensile loading and then examined using the Scanning Electron Microscopy (SEM). Laminating and thickening with a few layers of the same material (the basalt fibre) resulted in 56.6% and 104.6% improvement in load-bearing capacity and energy absorption, respectively. When these extra layers of basalt fibre for local thickening were replaced with the carbon fibre, an improvement of 80.2% and 167.3% in load-bearing capacity and energy absorption capacity, respectively, was attained. SEM imaging revealed that the addition of a few layers at the joint location altered the final failure mode from shear to interlaminar failures without substantially affecting the post-failure behaviour. This study revealed that localised inter-ply hybridisation is an important design parameter for bolted joints so as to enhance the bearing performance of the joint.