A delay-time model with imperfect inspection for aircraft structure subject to a finite time horizon

According to the failure characteristic of aircraft structure, the delay-time model is an effective method to optimize maintenance activities of aircraft structure to decrease maintenance cost rate. In order to be consistent with the actual situation as much as possible, imperfect inspections, threshold and repeated intervals are been considered in the delay-time model. What´s more, the all exsiting delay-time models assume that the inspections are over an infinite time horizon that doesn´t match the reality, so a delay-time model with imperfect inspection for aircraft structure subject to a finite time horizon is proposed to solve the above problem. In the proposed model, the nonhomogenous poisson process is studied and adopted to obtain the renewal probabilities due to defects or failures between the different two successive inspections, and an algorithm is applied based on the Nelder-Mead downhill simplex method to solve the model. Finally, a numerical example is illustrated as a case study, and the result proves the model validity and effectiveness.