Nonlinear analysis and damage monitoring of a one-sided patch repair with delamination

A simple analytical model using beam theory is developed to study a one-sided patch structure with delamination, considering the effect of large deflection and thermal stress. The method is based on the concept of equivalent delamination, which is analytically defined and employed to describe delay in load transfer between patch and parent plate with eccentrically aligned neutral axes. The analytical model has closed form solutions and good agreement with nonlinear finite element analysis (FEA) as well as experimental results is shown. The relation between the delamination propagation and the strains at monitoring locations is derived and feasibility of delamination monitoring based on surface strains is analytically demonstrated.