变厚度曲面构件超声检测灵敏度补偿

Sensitivity compensation method in ultrasonic inspection for curved components with variable thickness

为了解决变厚度曲面构件超声检测灵敏度补偿问题,提出声场计算与试验测量相结合的补偿方法.描述了单个高斯声束在介质中传播及穿透曲界面时的声场变化,根据自动探伤时探头位置、工件厚度和形状,利用多元高斯声束叠加方法,推导出水浸穿透法超声检测系统接收声场模型.在实际应用中,考虑介质吸收、散射引起的衰减,衰减系数通过试块插入取代法测量出.采用修正后的接收声场模型可以预测不同检测参数下的接收声压,准确计算出各点接收声压的衰减,进行灵敏度补偿.试验结果验证了该方法的正确性和实用性.

A new compensation method was proposed in order to solve the compensation problem in ultra- sonic inspection for curved components with variable thickness. The method combined sound field calcula- tion and experimental measurement technique. The Gaussian beam was introduced in order to calculate the receiving transducer ultrasonic field. The analytical expressions for the amplitude and phase of a Gaussian beam were described after propagation through media and interactions with curved interfaces. According to the conditions such as component thickness, shape and probe location, the receiving sound model of through-transmission ultrasonic inspection system was deduced based on multi-Gaussian beam superposi- tion method. In practice, additional attenuation caused by medium absorption and scattering should be considered. After the attenuation coefficient was measured by the method named inserted and substituted technique, the receiving sound model was modified. Then the receiving sound pressure was predicted with different parameters based on the modified model, and attenuation of the receiving sound pressure was cal- culated for sensitivity compensation. Experimental results showed the correctness and effectiveness of the new method.