剩余吸收层对激光冲击效果影响的实验研究

激光冲击过程中,剩余吸收层对冲击效果影响显著,但其影响规律少有人关注。文中选择厚度、材质不同的材料作吸收层,实施激光冲击,控制激光参数,使得靶材表面留有剩余吸收层。通过表征靶材表面冲击区域凹坑尺寸、力学性能,以及直接检测冲击时靶材背面的冲击波信号,研究剩余吸收层对冲击效果的影响规律。结果表明:剩余吸收层会显著衰减冲击波,进而削弱靶材的冲击效果;对确定的约束层和靶材,存在具有最佳声阻抗值的理想吸收层,使得作用于靶材的冲击波强度最大;激光冲击时,为获得好的冲击效果,必须根据约束层、靶材等,选择合适吸收层,优化吸收层涂覆厚度。文中结果为激光冲击时吸收层材质和厚度的选择提供了依据。

Experimental study on the effect of the remaining absorbing layer on laser shock processing

Remaining absorbing layers have a significant influence on the shock effects of metal samples in laser shock processing(LSP). However, the influence laws are still pending. In this paper, the experiments of LSP were conducted with different materials as the absorbing layers. The influence of the thicknesses of the absorbing layer was also studied. To guarantee that there were remaining absorbing layers on the target surface after shock, the laser parameters were carefully chosen. The influence laws of the remaining absorbing layers on the laser shock effect were researched by measuring the laser shock induced-pit sizes and the mechanical properties of the shocked zones. Furthermore, the shock wave signals on the back of the metal samples were tested by PVDF detector. Experimental results show that, the remaining absorbing layers can attenuate shock wave seriously. Therefore, the shock effects are weakened accordingly. Through the experimental and theoretical research, it can be found that there exist an ideal absorbing layer with the optimal acoustic impedance, when the confinement layer and metal sample are determined. With the ideal absorbing layer, we can get the strongest shock effect. For achieving good results in LSP, the absorbing layer material should be carefully chosen according to the confinement layer and metal sample. In the same time, the thickness of an absorbing layer should be controlled reasonably. The results of this paper can provide guidance for choosing the most appropriate absorbing layer for different metal samples in LSP.