Fatigue analysis of cracked thick aluminum plate bonded with composite patches

Repairs of metallic aircraft structures with composite patches have been accepted as a reliable technology, and studies for crack repairs to 11.43 mm thick aluminum plate are conducted in this paper. The stresses analyses are performed for four different aluminum plates, including no crack, with crack, with crack and single-side patched composites, as well as crack and double-side patched composites. The stress intensity factor analysis and the fatigue life calculations are performed for the following two cases: the cracked aluminum plate and the cracked plate repaired with the composite patches. The fatigue experimental tests for the above structures were conducted with MTS test machine. The Paris law of crack propagation and the nonlinear material properties of the aluminum combined with the FEM is to predict the fatigue life. It is showed that fatigue crack propagation characteristics obtained from FEM match very well with the experimental results.