Verified and Validated Software for Three-dimensional (3-D) Fatigue Crack Growth and Stable Crack Extension

A user-friendly software package for rapid fatigue evaluation of specific scalable flaw geometries, as well as stable tearing after crack length reaches a specified size, is being developed. The package will employ modified CRACK3D code and use VCCT with 10-noded tetrahedral elements to determine fatigue crack tip parameters (e.g. dK1, dK2, etc.) for fatigue cracks undergoing (a) mixed mode, in-phase fatigue conditions and/or (b) out-of-phase fatigue conditions, performing research that compares experimental evidence to computational predictions. To simplify the computational overhead, a computational model database with multiple selected flaw geometries and specimen configurations (e.g., corner crack from hole in tension) will be developed and a graphical user interface developed to efficiently convert model data into CRACK3D format for rapid analysis capability of scaled geometric configurations. BENEFIT: Automated scaling of models in the database will increase productivity of aerospace engineering personnel by simplifying the process of (a) building a FE model with cracks in several sizes and configures, (b) automating extraction of information necessary for decision making and (c) extending the concepts not only to uniaxial fatigue but to mixed mode fatigue conditions and even out-of-phase fatigue so that such conditions can be evaluated when necessary. It is expected that initial commercialization will be focused on the USAF and other DoD agencies requiring the use of the specific specimen geometries developed during Phase Additional commercialization will focus on specific structural areas where fatigue crack growth simulations are required on a consistent basis and the need is highest (e.g., tier 1 suppliers). Since the modules developed during this phase will reduce the cost of man power required for conducting crack growth simulations and minimize the requirement on engineer’s knowledge for correct use of the our simulation tool, expansion into these areas is consistent with the capabilities of the Phase II software.