An Experimental Study on Static Strength of Interference-fit Composite Joint with Blind Pumping Bolt Fastener

The experimental investigations were conducted in order to study the static strength of the mechanically fastened composite joints, involving interference-fit joint with blind pumping bolt and Sliding-fit joint with high lock bolt. The joint type of the specimens studied was single-bolt, double-lap, which is a standard test configuration in ASTM for composite joints. Interference-fits with different interferences and Sliding-fit were considered. During static tensile testing, the deformation of the bearing hole was measured by extensometer. According to ASTM D 5961 standard test method, the static strength and the static bearing strength defined as the bearing load at which the pin relative displacement is deformed to 4% the pin diameter (4%D) were obtained. Experimental results show that suitable interference can increase the static strength in comparison with the Sliding-fit case, and excessive interference can decrease the static strength. For the composite (T700/QY8911) and laying studied in this paper, when the interference is 0.5%, the static strength is increased by 2.8%; but when the interference is 3%, the static strength is decreased by 1.9%, comparing with the Sliding-fit joints.