铝合金材料残余应力及缺陷对裂纹扩展的影响

Effect on crack propagation behavior due to residual stress and defects in aluminium alloy

对于铝合金材料中存在的Ⅰ型裂纹及混合型预裂纹,研究了残余应力及其材料中存在的缺陷对其扩展方向的影响.对应于实验过程中的实际裂纹,通过有限元解析模拟计算出无残余应力状态下裂纹端部的应力强度因子KⅠ和KⅡ,从理论上利用Erdogan-Sih的б0假说对裂纹的扩展方向作了预测.结果表明,无论是Ⅰ型预裂纹还是混合型预裂纹,其预测的裂纹扩展方向都与裂纹扩展的实验结果基本吻合.即裂纹的扩展方向主要受到循环载荷的影响,而与残余应力无关.

For cracks under mode Ⅰ and mixedmode conditions in aluminium ally, is studied effecting on direction of crack propagation due to residual stress and defects. Stress intensity factors KⅠ and KⅡ are calculated by finite element method （FEM） analysis with a ideal crack in a finite plate, corresponding with a experimental crack. So the direction of crack propagation could be predicted by applying 60 maximum criterion proposed by Erdogan - Sih. As a result, the crack propagation paths predicted by FEM are in good agreement with the experimental results, either mode I nor mixed - mode cracks. That is the direction of crack propagation is determined by the cyclic component of stress intensity factors, but it had nothing to do with the residual stress.