激光冲击诱导应力波的机理初探

Primary Study on Mechanism of Stress Waves Induced by Laser Shocking

激光冲击处理时，用高功率密度脉冲激光束辐射金属表面。表面材料急剧气化，产生向材料内部传播的应力波。当应力波峰压大于材料的动态屈服强度时，使金属材料性能发生改变。用功率密度为3．88×1012W／m2、5．7×1012W／m2，脉宽为50ns的激光冲击覆盖玻璃约束层的铝试件表面，采用PVDF压电传感器测出距冲击表面0.1mm处的试件内应力波形。试验表明：数据可靠，它为激光冲击处理技术的工程应用提供了理论依据。

In the laser-shock process, the metal surface is irradiated with a high -power-density pulsed laserbeam. Rapid vaporization of the surface produces a compressive shock wave which propagates into the material. Whenpeak pressure of stress waves is bigger than the dynarnic yield strength of the material, the metal properties arechanged. Shock pressure measurements are made with the use of PVDF gauges applied on the back face of 0.1mmthick alurninum targets,covered with glass overlays and irradiated by laser pulses of 50ns duration,at incident laserpower density 3. 88 ×1012W/m2 and 5. 7×1012W/m2. Results show that the data are reliable and provide the theoreti-cal basis for engineering applications of laser-shock processing.