Study on T-bolt and pin-loaded bearing strengths and damage accumulation in E-glass/epoxy blade applications

In this paper, the ultimate bearing strengths of pin-loaded double shear and T-bolt loaded connections were studied in thick composites, where the diameter of the pin equates to the thickness of the laminate. These bearing strengths were obtained for E-glass / Epoxy laminates of [(±45, 03)n ,±45], and a Vf of 54%. It is found that the values for ultimate bearing failure and first non-linearity of pin-loaded connections should be reduced by 25% and 38% respectively, when applied to T-Bolt connections. The failure modes prior to ultimate failure were primarily dominated by fibre matrix shear out and delamination. As far as laminates with specific reinforcement architecture and a large percentage of reinforcement orientated to the load axis are concerned, the long term service life of T-Bolt connections may be impacted due to the visible onset of damage at a similar level to that accepted by Germanischer Lloyd for load introduction zones.