微观缩松对齿轮箱箱体疲劳强度的影响

Effect of Micro Porosity on Fatigue Strength of Aluminum Alloy Gearbox

微观缩松是铝合金齿轮箱箱体中常见的缺陷之一,对齿轮箱的安全服役带来不利的影响。基于三维代表体积单元法建立微观缩松有限元模型,研究微观缩松对铝合金材料弹性模量、屈服强度和疲劳强度的影响规律。通过显微分析测得箱体中一典型缩松缺陷的孔隙率,结合缩松缺陷区域的材料力学性能完成箱体的局部疲劳强度评估。结果表明:随着铝合金缩松区域孔隙率的增加,AlSi7Mg材料的等效弹性模量、屈服强度和疲劳强度都显著降低,当孔隙率为10%时,材料屈服强度由195.5 MPa下降至157.0 MPa,铝合金箱体的局部疲劳安全系数下降15.6%。

The micro porosity is one of the common defects in aluminum alloy gearbox.which has an adverse impact on the safe service of the gearbox.In this paper,a finite element model of micro porosity is built based on the three-dimensional representative volume element,and the effects of micro porosity on the elastic modulus,yield strength and fatigue strength of aluminum alloy were investigated.Then,a porosity in the gearbox was measured by microphotography and the local fatigue strength was evaluated according to the mechanical properties of materials in the micro porosity area.The results show that the equivalent elastic modulus,yield strength and fatigue strength of AlSi7Mg decrease significantly with the increase of porosity.When the porosity is 10%,the yield strength of the material decreases from 195.5 MPa to 157.0 MPa,and the local fatigue safety factor of the aluminum alloy box decreases by 15.6%.