CAJ | 학술논문

在疲劳断裂的中心圆孔试样孔壁取样进行显微硬度与残余应力的测试，结合有限元模拟结果对测试数据进行分析，从孔壁强度变化的角度研究孔零件在拉-拉载荷作用下发生疲劳断裂的原因。结果表明：疲劳断裂中心圆孔试样孔壁出现显微硬度梯度，长度方向孔壁表面获得最大硬度，宽度方向孔壁亚表层获得最大硬度，说明孔壁不同部位经受循环塑性应力影响程度不同，宽度方向孔壁发生应变硬化后循环软化成为薄弱区域；孔壁不同部位获得不同的切向残余应力场分布，长度方向孔壁表面获得最大残余压应力，宽度方向孔壁亚表层获得最大残余压应力，应力集中效应最强的宽度方向孔壁表面成为薄弱区域。
재피로단렬적중심원공시양공벽취양진행현미경도여잔여응력적측시，결합유한원모의결과대측시수거진행분석，종공벽강도변화적각도연구공령건재랍-랍재하작용하발생피로단렬적원인。결과표명：피로단렬중심원공시양공벽출현현미경도제도，장도방향공벽표면획득최대경도，관도방향공벽아표층획득최대경도，설명공벽불동부위경수순배소성응력영향정도불동，관도방향공벽발생응변경화후순배연화성위박약구역；공벽불동부위획득불동적절향잔여응력장분포，장도방향공벽표면획득최대잔여압응력，관도방향공벽아표층획득최대잔여압응력，응력집중효응최강적관도방향공벽표면성위박약구역。
Further research was performed to find out the causes of fatigue fracture from the perspective of hole wall strength change under tensile load;test data were analyzed based on the tested microhardness and residual stress, combined with the finite element simulation result. The analysis results show that the fatigue fracture samples present microhardness gradient. The hole wall surface of length direction has maximum hardness;the hole wall subsurface of width direction has maximum hardness. The effect of cyclic plastic stress on the hole wall differs with the change of position of the hole wall. The hole wall of width direction presents strain hardening first and then cyclic softening, and thus becomes the weak area. Different position of hole wall has different tangential residual stress field distribution. The hole wall surface of length direction has maximum residual compressive stress;the hole wall subsurface of width direction has maximum residual compressive stress. The hole wall surface of width direction becomes the weak area, resulting from stress concentration effect.