Theoretical Model of Non-stationary Gamma Strength Degradation Random Process Based on P-S-t Curve
The degradation process of components'strength generally changes with time and has different statistical characteristics in various periods,belonging to a typical non-stationary process.Due to the difficulty in directly measuring the data representing degradation states(wear,fracture,etc.)during the degradation process and the lack of degradation data,the P-S-t curve,which characterizes the fatigue performance of the material,is relatively easy to obtain.Therefore,the shape parameter of the Gamma process can be assumed as a nonlinear function and the P-S-t curve of material is applied to estimate the characteristic parameters of the Gamma process in this paper.Based on this assumption,a theoretical model of the non-stationary gamma strength degradation process based on the P-S-t curve is established.A numerical example shows that the proposed theoretical model can effectively describe the trends of strength degradation.This provides a new theoretical foundation for time-varying reliability analysis.
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