径向压电超声传感器的制备及其在混凝土结构健康监测中的应用

发布时间：2018-03-19 19:23

本文选题：混凝土　切入点：健康监测　出处：《济南大学》2015年硕士论文　论文类型：学位论文

【摘要】：现在常用的超声传感器多用金属封装层做外壳,外贴于混凝土结构表面使用,不容易与混凝土相耦合,受到环境影响较大,从而使得测试信号严重的失准。且现在常用的压电超声传感器指向性单一,难以实现在多方向上的接发超声波信号。为了克服以上所述缺点,本论文致力于研制一种埋入式径向压电超声传感器,与混凝土相容性好,能够实现埋入混凝土结构中多方向的接收和发射超声信号。本论文的开展主要涉及到了径向压电超声传感器的制备以及其在混凝土缺陷监测中的应用,具体如下：(1)本实验以尺寸为24mm×20mm×15mm(外径×内径×高)的PZT-52压电陶瓷圆管作为接受型径向超声传感器的压电元件,以尺寸为25mm×22mm×14mm的PZT-41压电陶瓷圆管作为发射型径向超声传感器的压电元件,以水泥、环氧树脂质量比为1：1的混合物作为径向压电传超声感器匹配层材料,以钨粉、水泥、环氧树脂质量比为2：1：1的混合物作为径向压电超声传感器的背衬层材料,来制备径向压电超声传感器。制备的传感器具有体积小、造价低、与混凝土兼容性好的优点,其大小和混凝土大骨料相当。(2)对不同结构尺寸的发射型径向压电超声传感器进行时域分析和频域分析,研究了匹配层厚度和背衬层结构对发射型径向压电超声传感器性能的影响。研究得出,当匹配层厚度为11mm时,发射型径向超声传感器的首波幅值与峰-峰值都为最大,此时传感器的发射灵敏度最高,符合四分之一波长理论；当传感器中添加背衬层材料时,会在一定程度上降低了发射型传感器的发射灵敏度,但是却增加传感器的带宽。通过对径向发射型传感器在水中不同角度下的幅值分析以及在混凝土各面上的频域分析,研究了发射型径向超声传感器发射指向性,得出发射型径向超声传感器在其径向360。方向能够实现均匀发射超声波信号。(3)对不同结构尺寸的接收型径向压电超声传感器进行时域分析和频域分析,研究了匹配层厚度和背衬层结构对接收型径向压电超声传感器性能的影响。研究得出,当接收型径向超声传感器匹配层厚度为11.5mm时,传感器接收超声波信号的灵敏度最高,符合传感器匹配层四分之一波长理论；当传感器添加背衬层后,接收型径向超声传感器的灵敏度略有下降,但大大的增大了传感器的声学衰减性能,一定程度上增大了传感器的带宽；通过对径向接收型传感器在水下不同角度下的接收幅值分析以及在混凝土各面上的时域分析,研究了接收型径向超声传感器接收指向性,得出接收型径向超声传感器在其径向360。方向上能够实现均匀接收超声波信号。(4)将所制备的径向发射型和接收型超声传感器分别埋入到混凝土,在不同的混凝土厚度下,采集声速、幅值、频率这些特征值,这些特征值随着测试距离增大逐渐变小,得出所制备的径向超声传感器对混凝土厚度的变化反映灵敏。在混凝裂缝的检测中,各超声特征值均随着裂缝尺寸的增大而减小,径向超声传感器对混凝土结构内部裂缝(缺陷)反映灵敏、准确；超声特征值测试数据的偏离率随着裂缝尺寸增大而增大,但相较于外贴式超声检测,数据偏离率要小,得出埋入式的测试方法大大提高了测试数据的有效性、可靠性。
[Abstract]:Now commonly used multi ultrasonic sensor with a metal shell encapsulation layer, and affixed to the surface of the concrete structure is not easy to use, coupled with concrete, have greater impact on the environment, thus making the test signal misalignment serious. And now the transducer used a single point, it is difficult to achieve sending and receiving ultrasonic signals in multi direction in order to overcome the above shortcomings, this paper is devoted to the development of a piezoelectric ultrasonic sensor embedded radial, good compatibility with concrete, can be embedded in the concrete structure in the direction of the receiving and emission ultrasonic signal. This thesis mainly involves the development of radial piezoelectric ultrasonic sensor and its preparation in the monitoring of concrete defects in application, as follows: (1) in this experiment, the size is 24mm * 20MM * 15mm (diameter * diameter * height) PZT-52 pressure tube as the radial circular piezoelectric ceramic ultrasonic receiving The piezoelectric element of the sensor, the size is 25mm * 22mm * 14mm PZT-41 pressure tube as the piezoelectric element, emission type radial ultrasonic sensor circular piezoelectric ceramics with cement, epoxy resin, the mass ratio of 1:1 mixture as a piezoelectric ultrasonic sensor, radial layer material, mud water, tungsten powder, epoxy resin quality the mixture ratio of 2:1:1 piezoelectric ultrasonic sensor as the radial backing layer material, the preparation of radial piezoelectric ultrasonic sensor. The prepared sensor has the advantages of small volume, low cost, good compatibility and advantages of concrete, the concrete aggregate size and phase. When (2) emission of different radial dimensions piezoelectric ultrasonic sensor for time domain analysis and frequency domain analysis of the matching layer thickness and the effect of backing layer on the radial emission performance of piezoelectric ultrasonic sensor. It was found that, when the thickness of the matching layer is 11mm, radial emission The first wave amplitude and peak - peak of ultrasonic sensor is the largest, the highest emission sensitivity of the sensor, with 1/4 wavelength theory; when the sensor is added back lining material, will to some extent reduce the emission emission sensitivity of the sensor, but increase the sensor bandwidth. By analyzing the amplitude of radial emission the sensor at different angles under water and frequency in the surface of the concrete analysis, to study the emission type radial ultrasonic sensor emission directivity, obtained emission radial ultrasonic sensor in the radial direction of 360. can achieve uniform emission of ultrasonic signal. (3) received radial structure of different size of the piezoelectric ultrasonic sensor is analyzed time domain analysis and frequency domain of the matching layer thickness and the effect of backing layer on the receiving radial performance of piezoelectric ultrasonic sensor. It was found that, when The receiving type radial ultrasonic sensor, layer thickness is 11.5mm, the sensitivity of sensor receiving ultrasonic signals is the highest, with 1/4 wavelength sensor matching layer theory; when the sensor is added back lining layer after receiving sensitivity type radial ultrasonic sensor decreased slightly, but significantly increased the sensor acoustic attenuation performance, to a certain extent increase the sensor by receiving bandwidth; amplitude analysis of radial receiver sensor at different angles of underwater and on the surface of the concrete in the time domain analysis of radial ultrasonic sensor receiving receiving directivity, the receiver can achieve uniform radial type ultrasonic sensor receiving the ultrasonic signal in the radial direction. 360. (4) of the the preparation of the radial emission and receiving ultrasonic sensors were embedded in the concrete, the thickness of concrete under different sound speed acquisition, The amplitude, the frequency of these characteristic values, the characteristic values as the test distance increases gradually, that the radial ultrasonic sensor by change of the thickness of concrete is very sensitive. In the detection of cracks in concrete, the ultrasonic feature values are decreased with increasing crack size, radial ultrasonic sensor on the internal structure of concrete cracks (sensitive and accurate defect); ultrasonic feature value test data rate increases with crack size increased, but compared to the outside attached ultrasonic testing data, the deviation rate should be small, the embedded test methods can greatly improve the efficiency, the reliability of test data.

【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU317;TP212

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