Stress ratio influence on Paris parameter and fatigue driving force pertinent to material properties

Abstract

Paris model is widely used since it was proposed in 1963 due to simplicity and universality, but it cannot consider stress ratio (R) effect and curve fitting is always needed to obtain Paris parameters when R is changed. Based on Goodman curve and analysis of 22 groups of fatigue crack growth (FCG) data, an analytical FCG rate model is proposed by linking Paris parameters and fatigue driving force at R ≠ 0 (from 0 to 0.5) to those at R = 0 and material constants (tensile strength and fatigue limit at R = −1). Results show that proposed model can well predict FCG behavior at different R values based on Paris parameters at R = 0.