Prediction of vibration fatigue life of fiber reinforced composite thin plates with functionally graded coating under base random excitation

This study presents the prediction of the vibration fatigue life of fiber reinforced composite thin plates (FRCTPs) with the functionally graded coating (FGC) under base random excitation. A dynamic model of an FGC-FRCTP under such an excitation loading is developed using the first-order shear deformation theory, random vibration theory, complex modulus method, etc. The natural frequency, stress frequency response function, and stress power spectral density curves are solved by the Rayleigh-Ritz method and frequency domain random vibration analysis approach. Moreover, the random fatigue life of the FGC-FRCTPs is successfully predicted by the Dirlik, Bendat, and Tovo-Benasciutti distribution. Finally, the preparation approaches of the FGC and the coated specimens are introduced, and detailed experimental investigations are performed. It has been found that the prediction errors of fatigue life using the Bendat, Dirlik and Tovo-Benasciutti distributions are less than -14.6 %, which proves that the current model can be employed to evaluate the fatigue resistance of the FGC-FRCTPs. Also, the impact of key coating parameters on the vibration fatigue life of the studied coated structures is evaluated. To improve their fatigue resistance, it is advised to select a large coating area, coating thickness ratio, and functionally graded index with the coating position near the constrained edge of the FGC-FRCTPs.