Behavior of Fatigue Crack Initiation and Growth in SM45C Steel under Biaxial Loading

J. Ocean Eng. Technol. 2004;18(6):84-90.

KIM SANG-TAE;PARK SUN-HONG;KWUN SOOK-IN;

School of Mechanical Engineering, Yeungnam University;School of Mechanical Engineering, Yeungnam University;School of Materials Engineering, Korea University;

이축하중을 받는 SM45C강의 피로균열의 발생과 성장거동

김상태;박선홍;권숙인;

영남대학교 기계공학부;영남대학교 기계공학부;고려대학교 재료공학부;

Keywords: SM45C, Biaxial Loading, Mean Stress, Crack Initiation, Crack Propagation, Crack Growth Direction

핵심용어: 이축하중, 평균응력, 균열생성, 균열 성장, 균열진전 방향

Abstract

Fatigue tests were conducted on SM45C steel using hour-glass shaped smooth tubular specimen under biaxial loading in order to investigate the crack formation and growth at room temperature. Three types of loading systems, were employed fully-reserved cyclic torsion without a superimposed static tension or compression fully-reserved cyclic torsion with a superimposed static tension and fully-reserved cyclic torsion with a superimposed static compression. The test results showed that a superimposed static tensile mean stress reduced fatigue life however a superimposed static compressive mean stress increased fatigue life. Experimental results indicated that cracks were initiated on planes of maximum shear strain whether or not the mean stresses were superimposed. A biaxial mean stress had an effect on the direction that the cracks nucleated and propagated at stage 1 (mode II).