Characteristics of Parameters for the Distribution of fatigue Crack Growth Lives wider Constant Stress Intensity factor Control

J. Ocean Eng. Technol. 2003;17(2):54-59.

일정 응력확대계수 제어하의 피로균열전파수명 분포의 파라메터 특성

김선진

부경대학교 기계공학부

Keywords: Fatigue Crack Growth Life, Weibull Distribution, Stress Intensity Factor, Non-Gaussian Random Process Simulation

핵심용어: 피로균열전파수명, 와이불 분포, 응력확대계수, 비가우스 확률과정 시뮬레이션

Abstract

The characteristics of the parameters for the probability distribution of fatigue crack growth life, using the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length equals the number of cycle curves that are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratios of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth life seems to follow the 3-parameter Wiubull,, showing a slight dependence on specimen thickness and stress intensity level. The shape parameter, $alpha$, does not show the dependency of thickness and stress intensity level, but the scale parameter, $eta$, and location parameter, ${gamma}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.