The effect of interference fit size on the fatigue life of bolted joints in composite laminates

An experimental investigation was conducted to determine the effect of interference fit size on fatigue life of double lap-type single bolted composite joints. Tension–compression reversed force/stress ratio, R = −1, was selected to evaluate the fatigue tests. The joints with blind bolts of four interference fit sizes, 0% (neat fit), 0.5%, 1.8%, 3% were tested separately. The appropriate levels of fatigue stress were determined by the ultimate bearing strength of the fastener structure obtained from the static tensile tests. The bearing stress and the fatigue life (S–N) date of different interference fit sizes specimen were presented and the relationship between interference fit sizes and fatigue life were obtained. The experimental results show that the interference fit can improve fatigue life of bolted joints compared to neat fit. For the composite material studied in this paper, the joints with 3% interference fit has the best fatigue performance in lower bearing stress (less than 540 MPa), however in higher bearing stress (more than 660 MPa), the best size of interference fit is 1.8%.