Closed-form analysis of external patch repairs of laminates

The increasing use of composite material leads to the question of appropriate maintenance and repair techniques for composite structures. A preferred repair technique applies adhesively bonded patches, after the damaged laminate material has been removed by cutting or drilling a hole. In the present paper within the scope of classical laminate theory, the problem of a laminate plate with an elliptical hole repaired by elliptical patches under in-plane and/or bending load is investigated. For the considered base plate and repair patch arbitrary bending extension coupling is allowed. There are no restrictions for the elastic membrane and bending stiffnesses of the underlying layups. With regard to the hole and patch design any size of the elliptical shape is admitted. The analysis of the repair problem is performed by the complex potential method. The complex potentials are defined by appropriate series representations for the base plate, the repair region and the hole domain. The derived closed-form analytical solution provides all essential field quantities for an accurate and effective assessment of the external patch repair.