激光冲击成形下3A21铝板料表面残余应力

Residual Stress of 3A21 Aluminium Sheet by Laser Shock Processing

激光冲击成形的重要特点之一就是能在工件表面形成残余压应力,起到强化的作用,对具有抗疲劳性能要求的航空结构件有重要意义。本文对激光冲击成形的3A 21防锈铝板的残余应力分布特性进行了研究。用X射线应力测定仪进行了三个方向残余应力的测量,建立了主应力计算公式,分析其形成机制与分布特性。试验结果表明:在脉冲能量42 J、脉冲宽度23 ns、脉冲功率1.2×109W作用下,板料正反两面产生的残余应力小于-100M Pa,且均为压应力,除变形区域顶点主应力方向为0°外,其他点的主应力方向约为-30,°且正方形板料对角线方向应力大于穿过中心边长方向的应力。

One of significant characteristics by laser shock processing is to form the residual stress on the workpiece surface and has a strengthening function. It is important to improve the fatigue strength of the aviation structure. Distributing characteristics of the residual stress of 3A21 antirust aluminum by laser shock processing are studied. Residual stresses of three directions are measured by XRD, and the counting formula of the main stress is built. Finally its forming mechanism and distributing characteristics are analyzed. Experimental results show that under conditions of the pulse energy 42J, the pulse width 23 ns, pulse power 1.2×10^9W, residual stresses of positive and negative sides are less than -100 MPa, and all are compressive stresses. Except for the main stress direction of deforming zone peak is 0°, the main stress direction of other points is approximately -30°. And the stress of the square sheet diagonal direction is bigger than that of the length direction of the across center side.