STOCHASTIC CHARACTERISTICS OF FATIGUE CRACK GROWTH RESISTANCE OF SM45C STEEL

摘要

Reliability analysis based on fracture mechanics requires knowledge of the on statistical parameters m and C in the fatigue crack growth law da/dN=C(ΔK){sup}m. The purpose of the present study is to investigate if it is possible to explain the change of parameter m by the fluctuation of C only. In this study, we apply the Paris-Erdogan law treating the parameter C as random and the parameter m as constant. Fluctuations in crack growth rate are assumed to be dependent only on C. The material resistance to fatigue crack growth (Z=1/C) is treated as a spatially random process, that varies along the crack path. The theoretical crack growth rates at various stress intensity factors are discussed. Additionally, the results of constant ΔK fatigue crack growth tests are reported for the structural steel, SM45C. The experimental data have been analyzed to determine the probability distribution of fatigue crack growth resistance.