激光冲击圆杆曲面诱导的残余应力数值模拟

采用有限元分析方法对激光冲击2024铝合金圆杆圆周曲面诱导的动态应力波及其残余应力进行了数值模拟。首先，在ABAQUS/Explicit显式分析模块中模拟了峰值压力为2 GPa激光冲击波在16 mm杆中诱导的应力波的传播过程。随后，在ABAQUS/Standard隐式分析模块中进一步计算在圆杆曲面上诱导的残余应力。在此基础上，分析了圆杆直径的大小对应力波峰值衰减和残余应力分布的影响，并进行了相关的试验验证。研究结果表明，峰值压力为2 GPa冲击波在16 mm的杆中诱导的弹塑性的应力波，应力波的峰值压力在400 ns时间内迅速衰减至250 MPa。冲击后，在距光斑中心小于0.5 mm冲击区域内分布不均匀残余应力，在光斑中心处形成了残余拉应力，轴向S11值为42 MPa；在半径为0.5~1.5 mm的冲击区域分布着残余压应力，S11值大约在250 MPa。应力波在传播过程中，其压力峰值衰减的速率随着杆径的增大而减慢，表面形成的残余压应力均随杆径的增大而增加。

Numerical simulation of residual stresses induced by laser shock on the circumference surface of round rod

The finite element method was employed to simulate the dynamic stress waves and residual stresses induced by laser impacting the cylindrical surface of round rod made of 2024 aluminum alloy. During simulation, the code ABAQUS/Explicit was firstly utilized to simulate the process of the stress wave propagation in the rod with the diameter 16 mm, which was induced by the laser shock wave with peak value 2 GPa. Subsequently, the other code ABAQUS/Standard was used to calculate further the residual stresses distributed in the cylindrical surface of rod. Based on the simulation results, the effects of the rod diameter on the attenuation of the peak pressure of the stress wave and the residual stress distribution were investigated. Corresponding experiments were carried out to validate the calculated results as well. The results indicate that the peak pressure of the stress wave induced by the 2 GPa shock wave decreases rapidly to 250 MPa within 400 ns in the round rod with diameter 16 mm. After laser shocking, an uneven residual stresses are distributed in central region of the impacted surface, and tensile residual stresses are formed at the center, where the value of residual stresses S11 reaches 42 MPa. While compressive residual stresses are formed in other impacted areas(radius from 0.5 mm to 1.5 mm), where the compressive residual stresses S11 are roughly 250 MPa. During the propagation of the stress wave, the decay rate of its peak pressure decreases with the enlarging rod diameter, and the compressive residual stresses distributed on the cylindrical surface increase with the increasing rod diameter.