The Role of Fracture Toughness and Residual Stresses in the Fatigue and Fracture Behavior of Large Thick-Walled Pressure Vessels.

摘要

The fatigue and fracture behavior of large thick-walled cylinders were examined as a function of yield strength and fracture toughness level and with respect to the presence of residual stresses induced by autofrettage. An increase in fatigue life associated with the presence of autofrettage residual stresses was observed. Also,fatigue life increased with increased fracture toughness level,with the fracture mode changing from brittle to ductile. These results are interpreted and discussed in terms of recent fracture mechanics concepts. Analytical fracture mechanics relationships relating residual stress and fracture toughness level to cyclic crack propagation rate and relating fracture toughness to critical crack depth are presented and compared to the experimental results. The results of the investigation are used to interpret the cause of premature fatigue failures and formulate the basis for a design approach for improving the fatigue and fracture resistance of thick-walled pressure vessels. (Author)