THE VIRTUAL CRACK EXTENSION METHOD FOR CREEP FRACTURE

Knowledge of the creep behaviour of materials used in structures which operate for many years is of fundamental importance when assessing the integrity of such structures. The additional consideration of cracks which may occur in metals is also important. For discrete cracks, characterising parameters associated with the creep conditions at the crack tip may be evaluated to determine whether the crack will grow slowly, rapidly, or remain stationary. For arbitrary structures containing such defects, the finite element method is particularly effective for calculating the time-dependent stress analysis. The particular fracture parameters can then be evaluated using algorithms based on existing technology for contour integration, and a new virtual crack extension technique. These features are described and compared in application to a laboratory compact tension specimen.