激光冲击对金属板料裂纹的影响模型

Study on Metal Crack Mode under Laser-shock Processing

研究了含有裂纹的金属板料在激光冲击波载荷作用下裂纹尖端应力强度因子和裂纹扩展速度的变化,利用断裂力学理论,对激光冲击加载下裂尖参数计算模型进行优化,采用应力强度因子叠加法,将外加载荷引起的应力强度因子和激光冲击后残留的残余压应力引起的应力强度因子叠加,推导出下裂纹尖端应力场强度因子表达式,由此可精确计算出金属板料的裂纹萌生寿命和裂纹扩展速度,实验验证了航空钛合金Ti6Al4V激光冲击后残余应力对裂纹扩展速度的影响,从而建立了激光冲击作用对板料裂纹扩展的影响的理论模型。

The relationship of the tip of the crack dynamic stress intensity factor and the velocity of the crack propagation in the metal sheet and laser shock parameters were investigated. A new mode of the tip of the crack was put forth by the theory of fracture dynamics, and then the dynamic stress intensity factor of the crack under the laser shock wave was also obtained. And superposition method was adopted to add dynamic stress intensity factor arisen by the external load and dynamic stress intensity factor arisen by the remains residual stresses. Transformation on the characteristics of aerial alloy Ti6Al4V by laser shock processing and influence on the fatigue life with these transformations were studied. The influence of surface residual stress by laser shock processing and the outer load on crack propagation velocity was discussed. Utilizing these solutions the crack initiation life were developed to evaluate exactitude.