超声聚焦探头在固体中辐射声场的动态光弹测量方法

Dynamic photoelastic measurement method of ultrasonic focusing probe radiating sound field in solid

超声聚焦探头在声场聚焦区域具有很高的检测灵敏度和分辨力,是工业超声检测中常用的探头。聚焦探头在固体中的聚焦特性直接影响检测效果,其传统测量方法通过水中聚焦参数间接换算而来,结果存在一定的误差。动态光弹法可以直接观测透明固体中的探头辐射声场,具有直观、无反射体或水听器的浸入影响、全场观测等特征。进一步采用圆偏振光并结合Senarmont补偿法,可精确测量透明固体中探头辐射声场的绝对应力分布,给出聚焦探头在固体中的聚焦参数,包括焦距、焦柱长度和焦斑宽度。实验测量结果与有限元仿真计算及小球反射法测量结果吻合较好,表明了动态光弹法定量测量聚焦探头辐射声场的可行性。

The ultrasonic focusing probe of high sensitivity and high resolution in the focus area is a commonly used in industrial ultrasound testing field.The focusing characteristics of focusing probe in the solid directly affect the detection effect.The traditional measurement method is indirectly converted by focusing parameters in water,which is not direct and accurate.The dynamic photoelastic method can directly measure the sound field parameters in the transparent solid with the characteristics of intuitive and no immersion effect of reflector or hydrophone in the whole field.The absolute stress distribution of ultrasonic probe radiation in transparent solid can be accurately measured by using circularly polarized light combined with Senarmont compensation method.And the focusing characteristic such as focal distance,focal length and width can be got meanwhile.The experimental results agreed with the finite element simulation and small ball reflection method well,which verifies the effectiveness of dynamic photoelastic method in measuring solid sound field of focusing probe.