冷胀提高6005铝合金疲劳寿命的机理

针对冷胀对6005铝合金疲劳裂纹产生和扩展的影响,用单边预切口试样研究了含缺陷结构冷胀后的疲劳寿命,分析了不同情况下新裂纹产生的循环数;并用ANSYS软件进行了数值模拟,确定冷胀产生的残余应力场和塑性区及在不同参数下冷胀度对其的影响.结果表明:孔径和冷胀度对最大残余压应力值影响不大,都在材料屈服强度1～1.1倍的限定范围内,而冷胀度对塑性变形区和残余压应力区大小的影响则非常显著.

Mechanism of Fatigue Life Improvement of Aluminium Alloy 6005 by Cold Expansion

Aimed at the effect of cold expansion on the initiation and propagation of fatigue crack of alloy 6005, the fatigue life improvement of the damaged structures after the cold expansion process was investigated with the single edge pre-cracked specimens. The numbers of cycles to obtain a new crack initiation are analysed from the different cases. A numerical investigation with ANSYS code is conducted to determine the residual stress field and the size of the plastic zone generated by the cold expansion , the influence of the degree of cold expansion on the different parameters shows that the maximum value of residual stress is localized between 1 and 1.1 of the yielding stress for any value of the diameter of the hole and of the degree of cold expansion, and the DCE has a remarkable influence on the size of the zone of compressive residual stresses and on the size of the zone of olastic deformation.