基于铝合金表面粗糙度的疲劳可靠性分析

Fatigue Reliability Analysis Based on Surface Roughness of Aluminum Alloy

铝合金受到循环载荷时,表面粗糙度作为基础参数之一对疲劳性能有着关键影响。基于铝合金材料的疲劳拉伸试验以及裂纹的断口分析,开展了材料表面粗糙度与疲劳寿命关系的研究。首先,通过打磨机对铝合金材料采用不同的打磨方式和打磨时间进行打磨,得到不同粗糙程度的试件;然后对这些试件进行疲劳拉伸试验,得到了各粗糙度参数与铝合金疲劳寿命之间的关系曲线;之后,通过金相显微镜对裂纹位置进行断口分析,并采用结构细节疲劳额定值(DFR)对粗糙试件的疲劳寿命进行可靠性分析。分析结果证明,铝合金材料的表面粗糙度对其疲劳寿命具有直接影响,同时表面粗糙度对铝合金试件的DFR值也有较大影响,即材料的表面粗糙度越低,其DFR值就会越高,且疲劳寿命就相对越长。

During the process of aluminum alloy subjected to cyclic loading,surface roughness as one of the basic parameters has a key influence on fatigue performance.Based on the fatigue tensile test of aluminum alloy materials and the fracture analysis of cracks,the study of the relationship between the surface roughness of the material and the fatigue life is carried out.First,the aluminum alloy material is polished by a polishing machine using different polishing methods and polishing time to obtain test pieces with different roughness.Then the fatigue tensile test was performed on these polished materials,and the relationship curve between the roughness parameters and the fatigue life of the aluminum alloy was obtained.After that,the fracture location of the crack was analyzed by a metallographic microscope,and the fatigue life of the rough specimen was analyzed for the reliability of the rough specimen using the structural detail fatigue rating(DFR).The analysis results show that,the surface roughness of the aluminum alloy material has a direct impact on its fatigue life.Meanwhile,the surface roughness also has a greater impact on the DFR value of the aluminum alloy specimen.That is,the lower the surface roughness of the material,the higher the DFR value,and the longer the fatigue life.