Three-Dimensional Fracture Mechanics Analysis

Efficient and accurate stress analysis methods are required to perform routine fracture mechanics analysis of surface and corner cracks in structures. Such analysis capabilities form the basis of fatigue life predictions for growing cracks in gas turbine engine structures. Boundary-integral equation (BIE) methods offer significant advantages to the fracture mechanics analyst in ease of use, accuracy, and modeling efficiency. Techniques for modeling three-dimensional fracture mechanics problems using the boundary-integral equation method are reviewed. Strain energy release rate modeling, together with crack opening displacement data, are found to give accurate and systematic estimates of crack front stress intensity factor distributions. Accuracy of the techniques are evaluated for well-known buried elliptical crack problems. Numerical models are extended to surface and corner cracks.