曲面构件阵列超声频域逆时偏移成像方法研究

Research on the curved-surface components array ultrasonic frequency-domain reverse time migration imaging method

曲面构件因其独特的结构和力学特性,广泛应用于航空航天领域。然而,未知的曲面形状导致阵列超声检测时,声传播延时计算不准确,影响缺陷检测的精度。为解决这一问题,提出了一种不依赖声传播延时的适用于曲面构件的阵列超声频域逆时偏移成像方法。首先,利用阵列超声全聚焦方法对曲面构件表面进行成像;然后,对成像结果进行阈值分割和曲线拟合,重构构件表面形状并建立二维声学特性分布模型;最后,通过频域逆时偏移将来自超声波源的正向传播波场与缺陷反射体的反向传播波场进行互相关成像。实验结果表明,所提出的方法可以有效实现曲面构件内部缺陷成像,与传统的阵列超声全聚焦方法相比,缺陷的成像质量提升66%以上,缺陷定量平均误差降低37.04%以上。

Curved-surface components are commonly utilized in the aerospace industry due to their unique structural and mechanical properties.However,the irregular shapes of these components pose challenges in accurately calculating ultrasonic propagation delays during array ultrasonic testing,which can impact defect detection precision.This article proposes a novel frequency-domain reverse time migration imaging technique for array ultrasonic testing of curved surface components that eliminates the need for relying on ultrasonic propagation delays.The method involves utilizing the total focusing method to create an image of the curved surface component,followed by threshold segmentation and curve fitting to reconstruct the surface shape and create a two-dimensional acoustic property distribution model.Subsequently,frequency-domain reverse time migration is used to correlate the forward and backward propagation wavefields,resulting in an internal image of the curved surface component.Experimental results on curved samples show that this method successfully enables internal defect imaging of curved-surface components.Compared with the traditional ultrasonic full-focus method,the imaging quality is improved by more than 66%,and the average quantitative error of defects are reduced by more than 37.04%.