DUCTILE FRACTURE SIMULATION OF A PIPE OF STEAM GENERATOR IN PWR

Ductile fracture of steam generator pipes may occur due to inner pressure. The final fracture process by inner pressure occurs as a burst of a pipe, and ductile high speed crack growth occurs with large deformation of the structure. For the simulation of such fracture process, Gurson's yield function is used as a constitutive equation, and large deformation theory is employed. As the simulation is conducted by load control condition, it is difficult to simulate burst phenomenon. Final fracture condition is discussed and finally crack opening displacement is chosen as burst fracture criterion. Fracture simulations of a pipe with multiple through cracks are conducted by changing distances between two crack tips. Burst loads are evaluated, and they are compared with estimated values by Maintenance rules. Surface crack problems are also simulated. Burst loads are also compared with results by limit load analysis method. Conservativeness of Conventional evaluation methods are studied and discussed.