激光冲击钛合金薄壁件动态响应及残余拉应力形成机制

为探究激光冲击薄壁件时残余拉应力的形成机制,利用ABAQUS软件对0.5mm钛合金薄壁件激光冲击条件下的冲击波作用规律和材料动态响应规律展开研究。结果表明,冲击波在薄壁件内反射时交替形成高数值拉伸波和压缩波,在压缩波和拉伸波的耦合作用下应力分布混乱并呈现"多峰"特点,形成了峰值为426 MPa、厚度达0.125mm的拉应力层,且最大残余拉应力位于表面处。基于冲击波反射规律揭示了薄壁件中残余拉应力的形成机制,并通过增加试件厚度以降低反射拉伸波强度发现5mm厚试件内最大残余拉应力仅为70 MPa,且表面处的拉应力转化为了压应力,从而提出了通过导波等方式控制应力波反射强度的薄壁件残余应力调控方法。

Dynamic Response and Residual Tensile Stress Formation Mechanism of Titanium Alloy Thin Walled Piece in Laser Shock Peening

To investigate the residual tensile stress formation mechanism of thin walled piece in laser shock peening, the shock wave propagation law and the dynamic respond law of 0.5mm titanium alloy thin walled piece are analyzed by ABAQUS software. The results show that when in reflecting in the thin walled piece, the shock wave forms high intensity tensile wave and compression wave in turn. The stress distribution in depth is disordered under the action of tensile wave and compression wave, and is characterized by multiple peaks. The tensile stress field is located within 0.125mm beneath the surface and the residual tensile stress up to 426 MPa appears on the surface. The formation mechanism of residual tensile stress is revealed based on the shock wave reflection law. The maximum residual tensile stress is only 70 MPa in the 5mm thick plate and tensile stress at the surface translates into compressive stress by reducing the intensity of reflected tensile wave. Therefore, based on the principle of controlling the reflection wave pressure, a method of stress field regulation by exporting shock wave is proposed.