双层界面下非近轴近似多元高斯模型的相控阵声场模拟

非近轴近似多元高斯模型克服了近轴近似条件的限制,能保证较大偏转角度下模拟声场的精确度和效率。根据双层介质的瑞利积分模型和单层介质的非近轴近似多元高斯模型,推导出双层介质中基于非近轴近似多元高斯模型的单阵元辐射声场计算模型。并在得到各阵元声束偏转聚焦的延迟时间基础上,累加得到基于非近轴近似高斯模型的超声相控阵横波检测辐射声场计算模型。模拟计算带丙烯酸树脂楔块的超声相控阵探头在钢中横波检测的声束偏转与偏转聚焦辐射声场,并与近轴近似多元高斯模型的横波检测声束的偏转聚焦辐射声场进行比较分析。对比分析结果表明非近轴近似多元高斯模型计算速度更快,用时约为近轴近似多元高斯模型的1/13。此外,非近轴近似高斯模型方法横波检测的聚焦声束覆盖区域更大,能量更集中,更适于远场区域检测。 

Radiation beam simulation of ultrasonic phased array based on a nonparaxial multi-Gaussian beam model with double interfaces

The nonparaxial multi-Gaussian model can overcome the limitation of paraxial approximation and guarantee the efficiency of sound field simulation under the larger deflection angle. Based on the Rayleigh integral model in double media and the nonparaxial multi-Gaussian beam model in single medium, a nonparaxial multi-Gaussian beam model of a single rectangular array for shear wave detection is proposed. According to the delay time of each array for beam steering and focusing, a radiation beam field of ultrasonic linear phased array for shear wave detection based on a nonparaxial nmlti-Gaussian beam model is obtained through accumulation accordingly. Then this paper calculates the radiated sound field produced in the interrogated steel medium by a linear phased array transducer mounted on an acrylic wedge, and the comparative analysis between the proposed model and the paraxial nmlti-Gaussian beam model is performed to simulate the beam field with double interfaces. Simulation results show that the proposed model runs faster than the paraxial multi-Gaussian model, and it takes about 1/13 time of the latter. In addition, comparison analysis results indicate that the proposed model can cover the bigger inspection area, has more concentrated energy, and is more suitable for the far field detection.