Effect of autofrettage on durability of CFRP composite cylinders subjected to out-of-plane loading

The objective of this study is to evaluate effects of autofrettage on durability of composite cylinders subjected to impact loading. Impact tests and damage observation were performed on the composite cylinders with and without autofrettage. Internal pressure tests were also conducted on the cylinders after impact tests. Simulated cycle tests were conducted on the rectangular plate specimens simulated as composite cylinders after impact tests. For the composite cylinder with autofrettage, absorbed energy became smaller, which was due to suppression of the damages, such as delamination. As a result, residual strength became larger and fatigue life became longer. It was clarified that CFRP composite cylinders with proper autofrettage were superior in the impact resistance.