Application of the critical load assessment method for stable crack growth analysis

A new systematic procedure has been developed for analyzing stable crack growth. In this method, the crack instability point can be predicted from a single J-l record, which is developed from a given material J r- curve and the J- integral-related solutions resulting from stress analysis of a flawed structure. Here l represents the physical load applied to the structure. The development of the J-l relation that satisfies the equilibrium state of crack growth is so simple that hand calculator analysis is possible for complex structural geometries with available j- related stress analysis results. The advantage of the new method over existing ones, such as the failure assessment diagram approach or the tearing instability theory, is that it can predict the critical physical load level and the crack instability point at the same time without resorting to the use of a fixed diagram or evaluating tearing modulus. The validity of the procedure has been demonstrated by solving a center-cracked tensioned panel with various loading mechanisms (displacement-controlled, load-controlled and mixed loading systems) and a pressure vessel geometry under internal pressure.