Burst and progressive damage behavior of composite overwrapped pressure vessels with multi-stepped butt joints between the dome and cylinder

This study investigates CFRP overwrapped pressure vessels featuring a bonded dome-cylinder structure. A stepped butt-joint structure without adhesive was employed as the bonding structure between the dome and cylinder section. The effects of joint length (step length) and joint position were examined through burst tests. After CFRP pressure vessels of four kinds simulating the dome/cylinder bonded configuration were produced, and subsequently subjected to burst tests. Using an X-ray CT scanner, internal damage in the pressure vessels was investigated after burst testing. The results indicate minimal influence of the step length L at the joint, and show that higher burst pressures were achieved when the joint was located closer to the dome section. Furthermore, progressive damage analyses based on finite element method with a cohesive zone model (CZM) were conducted to evaluate the experimentally obtained results. Damage behavior estimated from the numerical simulation roughly agreed with the experimentally obtained results.