Grey and Markov Prediction Model with Modified Residual Error of Aircraft Structure Lifetime in Corrosion Environment

Due to the limited sample sizes and random fluctuations of actual structure corrosion data of aircrafts in service, a lifetime prediction model of corroded aircraft structure was built based on grey theory. A Markov transfer equation was introduced to modify the residual error in order to improve the prediction accuracy of above model. The corrosion maintenance data of frame structure in cargo of a fleet containing 11 aircrafts with same classic type were collected to make the numerical analysis. The results show that the frame structure should be replaced according to the maintenance manuals because it will reach the second corrosion state in the age of 15 years, which means this kind of frame structure will be failure. The average relative error between predicted value of improved grey Markov model and actual value is 0.44%, obviously lower than that of uncorrected gery model 1.64%, and meets the requirements of engineering accuracy. Moreover, the predicted result bsaed on the model conforms to the actual outcomes of aircraft frame structure in civil aviation, which indicates that proposed model can be used to predict the lifetime for aircraft structure in service in corrosion environment.