Fatigue design of an autofrettaged thick-walled pressure vessel using CAE techniques

order to increase the fatigue life of an autofrettaged thick-walled pressure vessel, computer aided engineering techniques were applied. The fatigue life increase of the external grooved pressure vessel was achieved by relieving the high-stress concentration at the external groove. Shape optimization of the external groove incorporating the finite element stress analysis was performed, resulting in an optimized double grooved pressure vessel which showed a 34% decrease in maximum equivalent stress compared with the conventional single grooved pressure vessel. The fatigue life increase of the double grooved pressure vessel was verified by the simulation fatigue tests using C-shaped specimens, resulting in a 10-times-longer fatigue life. The predicted fatigue life of the pressure vessel using the local strain approach agreed with the simulation fatigue life within a factor of three. (C) 1998 Elsevier Science Ltd.