喷丸表面粗糙度对疲劳寿命影响研究

摘要

为研究喷丸处理对铝合金表面粗糙度及其抗疲劳性能的影响,文章提出一种采用数值模拟计算表面粗糙度的方法.首先利用ABAQUS有限元软件建立多丸粒喷丸强化数值模型,将得到的残余应力结果与文献实验结果进行对比以验证该模型的准确性.然后选用轮廓最大高度Rz作为表面粗糙度参数,设计正交试验研究弹丸尺寸、冲击角度、冲击速度和弹丸数量对工件表面粗糙度的影响程度,进而分析喷丸表面粗糙度对应力集中系数和疲劳裂纹萌生寿命的影响.结果表明:四因素对Rz的影响程度依次为:弹丸直径>冲击角度>冲击速度>弹丸数量.疲劳裂纹萌生寿命受表面粗糙度的影响,但两者间并非一一对应关系.应力集中系数由工件表面粗糙度和弹坑底部曲率半径共同影响,且两者呈反比关系,即应力集中系数越大,疲劳裂纹萌生寿命越短.%In order to research to the effects of shot-peening on surface roughness and fatigue life about a-luminum alloy, a shot-peening numerical model with multi pellets was put forward using ABAQUS soft-ware to simulate shot-peening roughness in this paper. The residual stress numerical results were compared with experimental results to verify the model. Then an orthogonal experiment was carried out to study the effects of pellet size,impact angle,impact speed and the number of projectile impact on the surface rough-ness, which chose maximum contour height Rz as the surface roughness parameter. Furthermore,the rela-tionships among shot-peening surface morphology, stress concentration coefficient and fatigue crack initia-tion life were analyzed. The results showed that the influence degree of four factors on Rz in descending order was projectile diameter> angle of impact> impact velocity> number of projectile. Fatigue crack initiation life was indeed affected by the surface roughness,but their relationship was not one-to-one corre-spondence. Stress concentration coefficient was affected by both surface roughness and curvature radius at the bottom of crater. In addition, the stress concentration coefficient was proportional inversely with the fatigue crack initiation life,which meant the greater the stress concentration coefficient,the shorter the fa-tigue crack initiation life.