缺陷散射对相控阵超声全聚焦成像的影响研究

相控阵超声全聚焦成像充分利用了检测信号,具有成像精度高、可进行缺陷识别等特点,是未来最具应用前景的相控阵成像算法之一。然而,目前相控阵超声全聚焦成像仍不能实现缺陷的高分辨率成像,无法对缺陷进行准确的定性、定量分析。为此,采用有限元仿真相控阵传感器的全阵列采集(FMC)过程,在全矩阵数据的基础上设计全聚焦成像程序,对圆孔和裂纹两种典型缺陷进行TFM成像,研究典型缺陷的TFM成像规律,从缺陷散射的角度分析影响相控阵超声全聚焦成像的因素。结果表明,实际检测中相控阵超声传感器只能接收到缺陷的部分散射信息,而相控阵超声在缺陷处的散射场分布与缺陷的类型、尺寸、角度及入射波类型、入射角度等因素有关,因此能否接收到缺陷散射的主要能量是影响全聚焦成像精度的关键。

Research on the effect of defect scattering on phased array ultrasonic TFM imaging

Fully utilized the detection signal, phased array ultrasonic total focus method (TFM) imaging can achieve high imaging precision and identify defects, which is one of the most promising future phased array imaging algorithms. However, the TFM imaging can not achieve high resolution imaging of defects, and can not make accurate qualitative and quantitative analysis. Therefore, in this paper, the finite element method (FEM) is used to simulate the full matrix capture (FMC) process of phased array sensors. A TFM imaging program is designed based on the full matrix data. TFM imaging is performed on two typical defects of circular hole and crack, and the TFM imaging law of typical defects is studied. The factors affecting phased array ultrasound imaging are analyzed from the perspective of the defect scattering. The results show that phased array ultrasonic sensor can only receive the partial scattering information of the defect in the actual detection. Moreover, the scattered field distribution of phased array ultrasound is related to the type, size, angle of the defect and incident wave type, and incident angle and so on. Thus, the main energy of the defect scattering can be received is the key factor to the accuracy of the TFM imaging.