The elastic-plastic failure assessment diagram of surface cracked structure

Surface crack is a common defect which causes the failure of engineering structures. Particularly, it is a main failure factor for high pressure vessel, reactor structure and astronautica structure. Therefore, the EPFM (Elastic-Plastic Fracture Mechanics) analysis for the surface cracked structure has been an intreasted problem. But, so far this problem has not been solved thoroughly because of its complexity. Recently, some researchers attended to solve this problem by means of 3-D finite element method, alternating method and boundary element method using the large-scale computer. Because of the high cost of calculation and the complexity of numerical technique, there are some difficults to apply these methods to solve the practical engineering problem.