基于相控阵超声成像的圆柱类部件自动化无损检测理论与实践的研究

发布时间：2018-06-16 08:07

本文选题：圆柱类部件 + 自动化相控阵超声成像　；参考：《浙江大学》2016年博士论文

【摘要】：管类、轴类及棒材等作为在国民经济、国防建设和高新技术等相关领域应用广泛的圆柱类部件,其质量优劣直接决定相关设备的运行性能和使用寿命,长期以来对无损检测技术具有强烈需求。尽管目前无损检测方法众多,但由于超声无损检测技术具有其它方法难以媲美的技术优势,特别是相控阵超声技术具有波束柔性合成与自适应控制能力,能方便满足不同的应用需求,可有效减少检测死区和盲区,已成为了无损检测领域研究的热点之一,并受无损评价大趋势的驱动下正朝自动化超声成像检测方向迈进,在圆柱类部件定量无损检测方面蕴含巨大的发展潜力。然而,自动化检测往往是在水浸的方式下实施,面向的对象将是一种叠层结构,其声波传播特性更为复杂,声学信号除受激励脉冲和介质作用外,还受到界面声学效应的影响,导致成像分辨率影响因素复杂,加之在运动过程中发射和接收信号加重了衍射效应,现有的相控阵超声成像技术在成像分辨率和实时性等方面还存在诸多不足,难以满足圆柱类部件自动化定量无损检测的应用需求。基于以上背景,本学位论文结合国家自然科学基金项目"基于旋转声场的高性能自动化在线超声无损检测理论与实践研究"(No.51175465),提出开展基于相控阵超声成像的圆柱类部件自动化无损检测理论与实践的研究。在分析超声无损检测和相控阵超声成像相关技术研究现状及其发展趋势,明确圆柱类部件相控阵超声成像检测机理的基础上,重点开展相控阵超声波束的波束域自适应合成、叠层结构相控阵超声稀疏化反演成像以及全矩阵频域成像等关键技术的研究,并结合图像形态学预处理及其分割方法,完成超声成像结果的处理与分析,实现圆柱类部件缺陷定量无损检测。同时,研发一套相控阵超声成像检测系统,以满足无缝钢管质量自动化检测的应用需求。具体的研究内容及创新点体现在:第一章,阐述圆柱类部件在国民经济发展和现代国防建设中发挥的巨大作用,以及开展圆柱类部件自动化相控阵超声成像检测技术研究的重要意义,分析超声无损检测技术和相控阵超声成像检测技术的研究现状及其发展趋势,明确目前相控阵超声成像检测理论和相关技术所存在的问题,为本文的研究指明方向。同时,对本学位论文的研究内容及各章节进行安排。第二章,开展圆柱类部件相控阵超声成像检测理论基础的研究。在研究圆柱坐标系下波动方程及其通解的基础上,明确圆柱介质内声波的传播机理及超声成像分辨率的影响因素,并利用空间脉冲响应声学模型对相控阵超声换能器的辐射声场进行计算仿真及特性分析。同时,以叠层圆柱结构为应用对象,研究相控阵超声入射波束的控制方法,实现非均匀介质中波束的偏转与聚焦,为后续研究奠定必要的理论基础。第三章,提出一种相控阵超声波束的波束域自适应合成技术,有效改善波束自适应合成的实时性。将相控阵阵元所接收到的回波信号转换至波束域后,在波束域内,利用信号协方差矩阵逆的高阶次幂乘逼近目标信号子空间的同时,以最小方差法获得波束合成的权值向量,并投影到上述信号子空间上,确定出波束域最优权值向量,从而实现自适应波束合成。仿真与实验结果表明,该技术在确保相控阵超声成像横向与对比度分辨率的基础上,能大幅减少运算量,有利于实际工程应用。第四章,提出一种叠层结构相控阵超声稀疏化反演成像技术,高效和高分辨率实现基于波束合成的叠层结构相控阵超声成像。通过脉冲响应方法建立融合声学衍射和电子效应的相控阵超声成像线性模型,将图像重建问题转化为基于缺陷稀疏化分布特性的正则化反演问题,构造含有l2和l1范数的优化目标函数,并利用可分离近似稀疏重建算法得到最优解,快速获得高分辨率的成像结果。仿真与实验结果表明,该技术可以明显改善相控阵超声成像的横向和纵向分辨率,并具有较高的成像实时性。第五章,提出一种叠层结构相控阵超声全矩阵频域成像技术,将基于虚拟聚焦的全矩阵成像技术推广到叠层结构中应用。利用傅里叶变换建立全矩阵采集方式下阵列接收信号模型的频域表达式,采用逐层递推策略对叠层结构的阵列接收声场进行频域重建,并以同样方法重建阵列发射声场,使之与接收声场在感兴趣叠层深度上关联,进而利用虚拟聚焦成像条件以实现成像点的虚拟聚焦,达到叠层结构高分辨率全矩阵成像的目的。仿真与实验结果表明,该技术能满足叠层结构相控阵超声全矩阵成像的应用需求,具有较高的成像分辨率和实时性。第六章,开展相控阵超声图像处理技术的研究,实现缺陷定量超声无损检测。在对相控阵超声图像进行自适应小波阈值消噪、双线性插值以及形态学开闭重建等预处理的基础上,利用自动图像分割和边界跟踪方法确定包含缺陷的图像区域,并通过缺陷区域局部归一化及图像二次分割,获得缺陷的形状与尺寸,实现缺陷的自动化定量无损检测。第七章,根据上述各章节的相控阵超声成像检测理论与关键技术的研究成果,开展圆柱类部件自动化相控阵超声成像检测系统与应用的研究。在完成总体方案的设计基础上,采用基于PXI总线的虚拟仪器架构体系,开发插卡式相控阵超声检测仪器,并结合机电一体化技术,完成圆柱类部件自动化相控阵超声成像检测系统的研发。同时,利用所研发的检测系统对无缝钢管开展实验应用研究,实现管类部件的自动化相控阵超声成像检测,以验证本文相关理论与技术的可行性和有效性。第八章,总结论文取得的研究成果和创新之处,并展望未来的研究工作。
[Abstract]:Tube, shaft and bar are widely used as cylindrical parts in the national economy, national defense construction and high technology and other related fields. Its quality directly determines the operating performance and service life of the related equipment. It has a strong demand for nondestructive testing technology for a long time. Loss detection technology has the advantages of other methods, especially the phased array ultrasonic technology has the ability of flexible beam synthesis and adaptive control. It can meet the different application requirements and can effectively reduce the detection of dead zone and blind area. It has become one of the hot spots in the field of nondestructive testing, and is driven by the big trend of nondestructive evaluation. The moving direction is moving towards the direction of automatic ultrasonic imaging detection, which has great potential in the quantitative nondestructive testing of cylindrical parts. However, the automatic detection is often carried out in the way of water immersion. The object facing is a layer structure, its acoustic wave propagation characteristics are more complex, acoustic signals are subject to excitation pulses and media. It is also affected by the effect of the interface acoustics, which leads to the complexity of the imaging resolution, and the diffraction effect is aggravated by the transmitting and receiving signals during the movement. The existing phased array ultrasonic imaging technology still has many shortcomings in the imaging resolution and real time, and it is difficult to satisfy the automatic quantitative nondestructive testing of the cylindrical components. Based on the above background, this thesis combines the National Natural Science Foundation Project "theory and Practice Research on high performance automated on-line ultrasonic nondestructive testing based on rotating sound field" (No.51175465), and puts forward the research on the theory and practice of the automatic nondestructive testing of cylindrical parts based on phased array ultrasonic imaging. The research status and development trend of ultrasonic nondestructive testing and phased array ultrasonic imaging are analyzed. On the basis of the mechanism of the phased array ultrasonic imaging detection of cylindrical components, the beam domain adaptive synthesis of phased array ultrasonic beams, the laminated structure phased array ultrasonic sparse inversion imaging and the full matrix frequency domain imaging are carried out. The research of key technology, combined with the image morphological preprocessing and the segmentation method, completes the processing and analysis of the ultrasonic imaging results, and realizes the quantitative nondestructive testing of the defects of the cylindrical parts. At the same time, a set of phased array ultrasonic imaging detection system is developed to meet the application requirements of the quality auto test of seamless steel tubes. The new points are embodied in the following aspects: Chapter 1, the great role of the cylindrical parts in the development of national economy and modern national defense, and the significance of the research on the automatic phased array ultrasonic imaging detection technology for cylindrical components, and the status and development of ultrasonic nondestructive testing and phased array ultrasonic imaging detection technology are analyzed. The trend is to clarify the existing problems of the current phased array ultrasonic imaging detection theory and related technology, and point out the direction for this study. At the same time, the research contents and chapters of this dissertation are arranged. In the second chapter, the theoretical foundation of the phased array ultrasonic imaging detection for cylindrical components is studied. On the basis of the process and its general solution, the propagation mechanism of acoustic wave in the cylindrical medium and the influencing factors of the resolution of ultrasonic imaging are defined, and the acoustic field of the phased array ultrasonic transducer is calculated and analyzed by using the spatial pulse response acoustic model. At the same time, the laminated cylindrical structure is used as the application object to study the ultrasonic incident wave of the phased array. In the third chapter, a beam domain adaptive synthesis technique for phased array ultrasonic beam is proposed to effectively improve the real-time performance of beam adaptive synthesis. The echo signal received by phased array element is converted to beamfield. At the same time, in the beam domain, using the high order power multiplication of the inverse of the signal covariance matrix to approximate the target signal subspace, the weight vector of the beam synthesis is obtained by the minimum variance method, and the optimal weight vector of the beam domain is projected on the above signal subspace and the adaptive beam synthesis is realized. The simulation and experimental results show that this technique is used. On the basis of ensuring the transverse and contrast resolution of phased array ultrasound imaging, the operation can greatly reduce the amount of computation and is beneficial to practical engineering applications. In the fourth chapter, a layered structured phased array ultrasonic sparse inversion imaging technique is proposed to achieve high efficiency and high resolution of phased array ultrasonic imaging of laminated structure based on beamforming. The response method establishes a linear model of phased array ultrasonic imaging with acoustic diffraction and electronic effects. The problem of image reconstruction is transformed into a regularized inversion problem based on the distribution characteristic of defect sparsity. The optimal objective function is constructed with L2 and L1 norm, and the optimal solution is obtained by using the separable approximate sparse reconstruction algorithm, and the high score is obtained quickly. The simulation and experimental results show that the technique can obviously improve the horizontal and longitudinal resolution of phased array ultrasound imaging, and has high imaging real-time performance. In the fifth chapter, a layered structured phased array ultrasonic full matrix imaging technique is proposed, and the full matrix imaging technology based on the virtual focus is extended to the stack. The frequency domain expression of the array receiving signal model under full matrix acquisition is established by Fourier transform, and the array receiving sound field is reconstructed in the frequency domain by the layer by layer recursive strategy, and the array transmitting sound field is reconstructed by the same method, so as to relate the received sound field to the interest layer depth, and then use it. The virtual focusing imaging conditions are used to realize the virtual focus of the imaging points to achieve the purpose of high resolution full matrix imaging of stacked structures. The simulation and experimental results show that the technology can meet the application requirements of the phased array ultrasonic full matrix imaging of the laminated structure, and has high imaging resolution and real-time performance. The sixth chapter is to carry out the phased array ultrasonic image. On the basis of adaptive wavelet threshold de-noising, bilinear interpolation and morphological opening and reconstruction, automatic image segmentation and boundary tracking are used to determine the missing image region, and the local normalization of the defect region is made by using the method of automatic image segmentation and boundary tracking. The shape and size of the defects are obtained by two segmentation and image segmentation. The automatic quantitative nondestructive testing of the defects is realized. In the seventh chapter, according to the research results of the theory and key technology of the phased array ultrasonic imaging detection in the above chapters, the research on the automatic phased array ultrasonic imaging detection system and the application of the cylindrical components is carried out. On the basis of the design of the case, the Virtual Instrument Architecture System Based on PXI bus is used to develop the intercalation phased array ultrasonic testing instrument, and the research and development of the automatic phased array ultrasonic imaging detection system for cylindrical parts is completed with the mechatronics technology. In order to verify the feasibility and effectiveness of the related theories and techniques in this paper, the automatic phased array ultrasonic imaging detection of this kind of components is presented to verify the feasibility and effectiveness of the related theories and techniques in this paper. The eighth chapter summarizes the achievements and innovations of the thesis, and looks forward to the future research work.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG115.285

【参考文献】