Abstract
A mechanically fastened joint in Carbon Fiber Reinforced Plastic (CFRP) laminates is necessary for its advantages in inspection, replacement and reliability, nevertheless its disadvantage in stress concentration. The mechanical joint should be designed to make the bearing failure mode occur because the strength is high and the joint fails non-catastrophically, while it fails catastrophically in other tensile and shear-out modes. In this study, the damage evolution of the pin joints for both [0/±45/90]3S and [90/±45/0]3S CFRP laminates and its difference between static and fatigue loading were discussed in detail. No difference between the macroscopic external appearance of damaged specimens under fatigue and static loading was observed, but the microscopic internal damage differed in critical damage and evolution. In static tests all the inside 0° layers had kinking at the maximum load and the kinking to be a trigger to the final failure with intense delamination and matrix crack. On the other hand, under fatigue loading the final damages mostly started from collapse at the loaded surface edge. It was also found that the total delamination length was longer in the case of fatigue at the same total matrix crack length and that [90/±45/0]3S presented higher strength than [0/±45/90]3S in both static and fatigue cases.
