为了研究约束层和激光功率密度对激光冲击强化AZ31B镁合金所诱发的冲击波的影响,采用响应快、频响高的绝缘膜组合式高聚物压电传感器和数字示波器对强激光诱发的冲击波进行测量。利用测得的有约束层和无约束层时的压电波形,分别得到相应的冲击波压力波形并进行比较;同时将不同激光功率密度下得到的压电波形转化为冲击波压力波形并进行对比。研究结果表明,在有约束层的情况下冲击波峰值压力是无约束层时的8倍左右,且脉冲的持续时间也有显著提高;在约束层的绝缘击穿阈值范围内,随着入射激光功率密度的增加,冲击波的峰值压力也随之增大。

In order to study the effect of overlay and laser power density on shockwave in laser shock processing to AZ31B magnesium alloy,the laser induced shockwave was measured by a polyvinylidene fluoride (PVDF) gauge with short rise time and high response frequency and a digital oscillograph. Based on the piezoelectric waves measured in the overlay geometry and direct ablation regime,pressure waves were obtained and compared;the pressure waves acquired in different laser power density conditions were also compared and analyzed. The research results show that the peak pressure of laser shockwave in the overlay geometry is about as eight times as it is in the direct ablation regime,and the duration time of the pulse is extended obviously. Below the dielectric breakdown threshold of the overlay,the peak pressure of laser shockwave is improved with the increase of the laser power density.