Innovative Approaches for Improving Progressive Damage Modeling and Structural Life Prediction of Airframes

Technical Data Analysis, Inc. (TDA) proposes to create a functional link between a finite element solver and UNIGROW, a fatigue and fracture mechanics program implementing the two-parameter approach to fracture mechanics developed by TDA and Dr. Grzegorz Glinka of the University of Waterloo, with support from ONR. This link will enhance the capability of both programs by providing a means of analysis automation for fatigue crack growth. Currently, fracture mechanics analysis relies on simplified models based on empirical rules to determine stress intensity factors. However, the sometimes poor correlation of these models to real structure leads to a large amount of uncertainty in fatigue crack growth calculations. The proposed product will allow any real structure to be analyzed for crack growth using the well established weight function methodology. After creating a component finite element model, a simple linear static analysis will determine stress distributions on any number of user-identified or automatically-identified crack planes. Those stress results will be linked to UNIGROW, which will utilize the weight function approach to determine accurate stress intensity factors and fatigue crack propagation. The end result will be enhanced fracture mechanics analysis capability, leading to safer, more efficient designs.