Damage Behavior and Failure Prediction Model of Protective Coatings for Aircraft Metal Structure under Multi-factor Coupling Effect

Samples simulating the substrate and its protective coating of central wing, flat tail shaft and other parts of aircraft were tested under multifactor coupling effect of ultraviolet ray, thermal shock, low temperature fatigue and salt mist. The damage morphologies and electrochemical parameters of different samples after different test periods were statistically analyzed. The results show that the damage is mainly color change and bubbling, and there is a certain correspondence between the damage morphology and the impedance modulus at low frequency. The range of low-frequency electrochemical impedance modulus at different failure stages and the corresponding failure morphologies were given in this paper. The protective coatings failure prediction models at home and abroad were investigated and analyzed. The failure prediction models mainly include impedance modulus data processing method and aging dynamic model. Based on the analysis of the limitations of the existing models, the aging dynamic model was improved, a full frequency aging dynamic model was proposed, and a new neuronal network failure prediction model was established. The prediction results of the models were compared and analyzed by using the experimental results of aluminum alloy, steel and their protective coatings under different experimental conditions.