Total Fatigue Life Assessment of Complicated Structures

Global Engineering and Materials, Inc. (GEM) along with its team members Northwestern University, Lockheed Martin, and Boeing Company, propose to develop an automatic software tool for 2D/3D fatigue crack growth prognosis of complicated structures under multi-axial loading. The XFAT toolkit will be developed by integrating a unified crack initiation and propagation model with an enhanced mesh independent extended finite element toolkit (XFA) for ABAQUS. A direct mesh independent crack path tracking will be used for a 2D crack while a fast and robust level set characterization and update will be implemented for an arbitrary 3D crack and its growth. To accurately determine the mixed mode fracture parameters, an interaction integral will be implemented for the direct computation of mixed-mode stress intensity factors. A unified crack initiation and propagation solution module will be developed for the total fatigue life assessment. The proposed technique permits crack initiation or arbitrary insertion of initial cracks, independent of a base 3D model, and allows non-self-similar crack growth pattern without conforming to the existing mesh or local remeshing. Verification and validation of both 2D/3D fatigue crack growth modules for Abaqus will be performed using test data collected from LM/Boeing and from GEMs existing Navy sponsored programs.