Fatigue Crack shape Variations by a Residual Stress and Fatigue Life Predition

J. Ocean Eng. Technol. 1993;7(2):68-78.

잔류응력에 의한 피로균열면 형상변화 및 수명예측

강용구,서창민,박원종

금오공과대학교 기계설계공학과,경북대학교 기계설계과,동환산업㈜기술연구소

Keywords: Residual Stress, Residual Stress Intensity Factor, True Effective Stress Intensity Factor, Crack Closure, Crack Growth Equation, Aspect Ratio, Life Predicton

핵심용어: 잔류응력, 잔류응력확대계수, 진유효응력확대계수, 균열닫힘, 균열성장식, 균열면 형상비, 수명예측

Abstract

Fatigue crack shape variation by a residual stress during crack growth and life predition are studied. An analytical method is presented to predict the influence of a residual stress due to heattreatment on crack shape variations. Computer simulation results using this me thod are graphically shown that crack growth rate to surface direction are decreased due to compressive residual stress exisiting in surface area. These results are commpared with experimental results. The fatigue life is also predicted by computer simulation of crack aspect ratio variation which is based on the surface crack length increment per unit cycle calculated from a-N diagram. Predited life is about 12 percent lower than experimental life.