用于结构损伤检测的OPFC超声相控线阵驱动理论及技术研究

发布时间：2018-05-06 13:58

本文选题：正交异性 + 压电复合材料　；参考：《江苏大学》2013年博士论文

【摘要】：用于声／电转换的超声相控阵驱动器是超声相控阵检测系统的关键组成部分之一,通过延时控制,超声相控阵驱动器具有自动聚焦和偏转的能力,可以对被测结构进行多方位快速扫描。由于相控阵驱动器直接产生超声波,因此它的结构形式及性能直接影响超声相控阵检测的性能和成像质量。针对复杂工程结构损伤特性及现有超声相控阵检测技术中驱动器存在的不足,在压电正交异性机理研究基础上,通过理论分析、数值仿真与实验验证研究了伸缩型压电正交异性纤维复合材料(Orthotropic piezoelectric fibe composite, OPFC)元件及相应的用于金属结构和混凝土结构损伤检测的OPFC超声相控线阵换能器,拓展了复杂工程结构无损检测新技术,为超声相控检测技术提供了理论和实验指导。基于力-电耦合理论,构造了伸缩型振动的压电正交异性纤维复合材料(OPFC)元件,系统地分析了各相材料特性、结构尺寸对OPFC驱动元件性能的影响规律,并对其驱动性能进行了测试分析。针对现有的超声相控阵换能器应用中单一PZT阵元力/电参数可设计性不足等原因,设计相应的用于金属结构和混凝土结构损伤检测的OPFC超声相控线阵换能器,突显出其驱动电压低,有效地抵制了栅瓣对有效信号的干扰；结合声场指向性分析,采用有限元法对金属中聚焦声场分布分析,研究不同参数变化时聚焦点处总位移的变化,得出最佳相控阵阵元间距、阵元宽度、阵元数等参数。研究了用于金属结构和混凝土结构损伤检测的OPFC驱动器的制备方法,对自行研制的叉指式OPFC元件进行了性能测试,并与常规PZT元件性能进行了对比分析,得出用于金属结构检测的叉指型OPFC具有低声阻抗和高机电耦合系数,而用于混凝土结构检测的OPFC超声驱动器的得灵敏度和带宽比传统换能器分别提高了3.9dB和27.21%。为有效克服材料阻尼对超声波传播过程的衰减,基于现场可编程门阵列(FPGA)的高集成度、高运行速度和可编程的特性,研制了16通道的相控延时和可控强度聚焦偏转发射/接收装置,实现了任意波形信号的直接数字合成,对OPFC超声相控驱动技术进行了结构损伤检测实验验证,取得了预期的效果。实验结果表明与现有超声相控阵驱动技术相比,其驱动聚焦能量、检测灵敏度都能得到提高,检测范围进一步扩大,验证了将OPFC超声相控线阵驱动/传感器用于结构损伤检测的可行性。
[Abstract]:Ultrasonic phased array driver for acoustic / electrical conversion is one of the key components of ultrasonic phased array detection system. By time-delay control, ultrasonic phased array driver has the ability of automatic focusing and deflection. The structure under test can be scanned quickly in multiple directions. Because phased array driver produces ultrasonic wave directly, its structure and performance directly affect the performance and imaging quality of ultrasonic phased array detection. In view of the damage characteristics of complex engineering structures and the shortage of actuators in the existing ultrasonic phased array detection technology, based on the research of piezoelectric orthotropic mechanism, the theoretical analysis is carried out. Numerical simulation and experimental results show that the stretching piezoelectric orthotropic piezoelectric fibe composite, OPFC) elements and the corresponding OPFC ultrasonic phased array transducers for damage detection of metal structures and concrete structures are studied. The new technology of nondestructive testing for complex engineering structures is extended, which provides theoretical and experimental guidance for ultrasonic phase control testing technology. Based on the mechanical-electric coupling theory, a piezoelectric orthotropic fiber composite material (OPFC) element with telescopic vibration is constructed. The characteristics of each phase material and the influence of the structure size on the performance of the OPFC driving element are systematically analyzed. The driving performance is tested and analyzed. Aiming at the lack of design ability of single PZT element force / electric parameter in the application of ultrasonic phased array transducer, the corresponding OPFC ultrasonic phased array transducer for damage detection of metal structure and concrete structure is designed. It highlights its low driving voltage and effectively resists the interference of the gate lobe to the effective signal. Combining with the analysis of the directivity of sound field, the finite element method is used to analyze the distribution of focused sound field in metal to study the change of the total displacement at the focal point when different parameters change. The optimum parameters, such as the spacing of phased array elements, the width of array elements and the number of elements, are obtained. The preparation method of OPFC driver for damage detection of metal structure and concrete structure is studied. The performance of cross finger OPFC element developed by ourselves is tested and compared with that of conventional PZT element. The cross finger type OPFC used for metal structure detection has low impedance and high electromechanical coupling coefficient, while the sensitivity and bandwidth of OPFC ultrasonic driver for concrete structure detection are improved by 3.9dB and 27.21, respectively. In order to overcome the attenuation of material damping on ultrasonic propagation process, based on the high integration, high running speed and programmable characteristics of FPGA (Field Programmable Gate Array), A 16-channel phase-controlled delay and controllable intensity focusing deflection transmitting / receiving device is developed. The direct digital synthesis of arbitrary waveform signals is realized. The structure damage detection experiment of OPFC ultrasonic phase-controlled drive technology is carried out. The expected results have been achieved. The experimental results show that compared with the existing ultrasonic phased array drive technology, its driving focusing energy and detection sensitivity can be improved, and the detection range is further expanded. The feasibility of applying OPFC ultrasonic phased array drive / sensor to structural damage detection is verified.
【学位授予单位】：江苏大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU317

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