Finite Element Method (FEM) for Bonded Repair Design

A repeatable finite element methodology will be developed to accurately simulate fatigue cracks initiation and propagation in aircraft wing components with unconventional bolted bonded patch repairs. The geometry and FEM parametrization and creation will be conducted using RapidFEM. The developed FEM methodology will leverage the fatigue analysis tools of ANSYS. During the iterative process, condensed stress quantities (such as the max principal stress, von Mises stress, etc.) will be used to find the crack initiation sites. The critical plane approach will be then employed to find the crack orientation, while Paris’ law will be used to determine the new crack extension using the stress intensity factor information at the vicinity of the crack front. To ensure the desired robustness and accuracy of the multiaxial fatigue life prediction tool and its ability to interpret and use the provided fatigue input data (S-N curve, etc.), various geometries with several repair types will be tested under single and combined fatigue failure modes. Low-cycle and high-cycle fatigue analyses will be considered and different types of load cycle profiles will be employed. A classroom training will be prepared and ready to administer. The developed methodology will be validated against current ASTM standards.