In the recent years, a number of studies on the fatigue crack opening and crack closure load have been carried out. Present investigation serves as an intermediate point to complete a failure prediction model with a more practical value for determination of leak before the break (LBB) problem in pressure vessels and pipes. An attempt has been made to solve this problem by using analytical, numerical and experimental methods. Method of linear fracture mechanics at analytical investigation by using the analogy between the stress strain state at stress concentrator and the crack tip and strain intensity factor is adapted to the nominal elastic-plastic loading. Investigation has showed that numerical results are in good agreement with the experimental results. However, the proposed analytical model satisfactorily matches with the experiment in the middle of the crack, which is acceptable for LBB conception, and incorrect at the crack tip, which is non-acceptable for the fracture mechanics conception.
展开▼
