斜楔块条件下超声换能器的声场仿真

摘要

Owing to that a large shaft is very difficult to be disassembled because of its complicated shape,large volume and quality,the fatigue cracks of shaft components are mainly tested by using a small angle longitudinal ultrasonic wave probe arranged on the end face of the shaft.Small angle longitudinal transducers are widely used in industry and for their reliable application,it is essential to have thorough understanding about the characteristics of radiation beam patterns produced in the medium.Considering the mode conversion and refraction at the interface,a model was developed based on the theory of spatial impulse response,which can be used to calculate the ultrasonic field of the small angle longitudinal transducer under wedge conditions.The ultrasonic field distribution patterns at various wedge angles were obtained by simulation.The field distribution in a half-round stair (HS) block was measured as an example,and the measurement results are in good agreement with the simulation results.The method can be used to simulate the acoustic field of small angle longitudinal transducers with different parameters,which is helpful to make the strategy decision for shaft inspection and improve the reliability of ultrasonic testing.%各种大型轴类零件形状复杂,体积和质量大,拆卸困难,主要用小角度纵波探头在轴端面实施探伤.小角度纵波超声检测方法在工业中有着大量的应用,对于小角度纵波探头的声场研究还较少.以空间脉冲响应为理论基础,根据界面条件下的波形转换以及超声波的透射规律,建立了小角度纵波超声探头在斜楔块条件下的空间声压模型,给出了其空间脉冲响应的计算公式,并仿真得到了不同斜楔块角度时介质中的声压分布图,利用半圆阶梯试块测试了声轴线的声压和指向性图,实验结果和仿真计算基本一致.该方法可用于不同参数的超声探头倾斜入射时的声场仿真,为制定轴类零件非拆卸情况下的检测策略,提高检测可靠性奠定基础.