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激光冲击强化技术是一种新型的材料表面改性技术。在实际应用中,由于激光光斑直径通常在20 mm以下,工件表面大范围的激光冲击强化需要采用多个光斑搭接。运用实验和数值模拟的方法,探讨了光斑在不同中心距下诱导的残余应力场的分布规律,研究了不同搭接率对残余应力分布的影响,以及两种不同加载顺序下表面残余应力的分布特性。结果表明:相邻光斑中心距对两光斑之间区域的残余应力有重要影响,随着两光斑中心距的减小,相邻光斑之间区域的应力场由残余拉应力转变为残余压应力;搭接率越大,获得的残余压应力幅值越大,残余应力分布越均匀;从中间到两侧的多点冲击方式能获得较大、较均匀的残余压应力。
Laser shock enhancement technology is a new type of material surface modification technology. In practical applications, a wide range of laser shocks on the surface of a workpiece require multiple spot overlap due to laser spot diameters typically below 20 mm. The distribution of residual stress field induced by different spot distances is discussed by means of experiment and numerical simulation. The influence of different overlap rates on residual stress distribution and the distribution of surface residual stress under two different loading sequences are studied characteristic. The results show that the center distance of adjacent spots has an important influence on the residual stress in the area between the two spots. With the decrease of the center distance of the two spots, the stress field in the area between adjacent spots changes from residual tensile stress to residual compressive stress. The larger the lap-lapped ratio, the larger the residual compressive stress is and the more uniform the residual stress distribution. The larger and more uniform residual compressive stress can be obtained from the multi-point impact mode from the middle to both sides.