Tensile Strength and Fatigue Properties of Z-Pinned Composite Lap Joints

摘要

The effect of z-pinning on the tensile strength, fatigue life and failure mechanisms of single lap joints is experimentally investigated. Under tensile loading, the tensile load to initiate delamination cracking in the adhesive bond-line to a lap joint can be reduced slightly by z-pinning, however the ultimate failure strength and elongation limit are improved by z-pins bridging the bond-line. Z-pinning is also highly effective in extending the tensile fatigue life of lap joints by the crack bridging mechanism. Transitions in the failure mechanisms were observed from joint debonding in the absence of pins to pull-out and/or shear failure of pins or tensile failure of the laminate, depending on the volume content and diameter of the z-pins. It is shown that under certain z-pinning conditions, bond-line delamination of the joint can be suppressed and the failure mechanism is changed to rupture of the composite laminate.