Applications of DTALE: Damage Tolerance Analysis and Life Enhancement [3-D Non-plannar Fatigue Crack Growth]

The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and the SGBEM solution for the crack in the local finite-sized subdomain. In addition, some crack growth models are used to advance the crack front in fatigue and other stable-carck-growth situations. The crack-surface mesh is also changed correspondingly in the BEM model, while the FEM model for the uncracked structure is kept unchanged. The automatic crack growth analysis is achieved by repeating the fracture analysis, and the life of the structural components is estimated. Furthermore, the initial crack size and shape in a structure, as emanating from a microscopic defect, can be determined by utilizing the automatic crack-growth feature. Some state-of-the-art numerical solutions are also presented to indicate the type of problems that can now be solved using currently available techniques. All these methodologies are embedded in a user-friendly software, DTALE (Damage Tolerance Analysis and Life Enhancement), which is available for commercial use , in the safety evaluation and life-estimation of a variety of structures. Life enhancement methodologies with deliberate introduction of residual stress-fields, is also a feature of DTALE. keyword: damage tolerance analysis, life enhancement, arbitrary 3D surface crack, finite element method, symmetric Galerkin boundary element method, the alter1 Center for Aerospace Research & Education, University of California, Irvine, 5251 California Avenue, Suite 140 Irvine, CA, 92612, USA nating method.