超声波在固体中传播的有限元模拟

发布时间：2018-07-05 14:14

本文选题：超声波 + 相控阵　；参考：《武汉工程大学》2014年硕士论文

【摘要】：波在传播的过程中如果改变了其单一的传播路径，就会发生反射、折射和衍射等现象。超声波本身是一种高频率的波，而且指向性很好，所以超声波检测的主要原理也是利用这些比其它波表现更加明显的现象于来检测评定被检测的对象是否存在缺陷。目前国内已经开始初步的应用处在国际上最为先进的两种超声检测方法：相控阵与TOFD（衍射时差法）。由于起步缓慢，相关人才紧缺，设备也相应的落后，为了促进超声波检测技术的发展，本文对超声波检测的两种先进方法进行了有限元数值模拟研究。总的来讲，完整的研究分成二个部分，模拟研究是第一步，反推模拟过程是第二步，这里只是作第一部分的研究。主要的目的是证明有限元模拟仿真TOFD法检测的过程是可行的，可以对检测进行辅助，弥补了TOFD检测手段的局限性。模拟系统是由超声探头、楔块与缺陷试块三个模型构成。超声波时机械波，符合一般弹性波的传播规律，首先确立其在固体中传播的动态波动方程，然后再在有缺陷的模型中用TOFD法与相控阵法进行检测，，最后模拟超声波的传播过程，与实验结果进行对比分析。结果表明仿真中的回波幅值精确度不高，而缺陷回波的时间精度很高，这说明了将数值仿真应用在只测量传播时间就可以对缺陷进行定量的TOFD法中是切实可行的。 TOFD的超声模型是根据惠更斯原理建立的，模拟的重点是怎么样模拟相控阵的波源发射超声波，怎么样施加载荷以及在哪施加载荷。使用TOFD检测方法得到的人工缺陷的实验检测结果与仿真结果的相符程度很高。从另外的角度上说，运用仿真手段在实际检测中对检测结果进行辅助分析是切实可行的。传统的检测手段模拟的结果中会波幅值的准确率不高，但是运用超声TOFD检测法只用测量回波时间，弥补了这一缺陷，两者相辅相成，仿真结果与实验结果的对比说明这种方法是有效的。
[Abstract]:The reflection, refraction and diffraction will occur if the wave changes its single propagation path in the process of propagation. Ultrasonic wave is a kind of high frequency wave, and its directivity is very good. Therefore, the main principle of ultrasonic detection is to use these phenomena, which are more obvious than other waves, to detect and evaluate whether the detected object has defects. At present, two kinds of ultrasonic detection methods, phased array and TOFD (diffraction time difference method), have been applied in our country. In order to promote the development of ultrasonic testing technology, two advanced methods of ultrasonic testing are studied by finite element numerical simulation in order to promote the development of ultrasonic testing technology, because of the slow start, the shortage of related talents and the corresponding backwardness of equipment. In general, the whole study is divided into two parts, the simulation is the first step, the backstepping simulation is the second step, here is only the first part of the study. The main purpose of this paper is to prove that the finite element simulation TOFD method is feasible, which can assist the detection and make up for the limitation of the TOFD detection method. The simulation system consists of three models: ultrasonic probe, wedge and defect test block. The mechanical wave of ultrasonic wave is in accordance with the general law of elastic wave propagation. First, the dynamic wave equation is established, then the TOFD method and phased array method are used to detect the ultrasonic wave in the defective model. Finally, the propagation process of ultrasonic wave is simulated. The results are compared with the experimental results. The results show that the accuracy of echo amplitude in simulation is not high, but the time precision of defect echo is very high. This shows that it is feasible to apply numerical simulation to the TOFD method, which can measure the propagation time only. The ultrasonic model of TOFD is established according to Huygens principle. The emphasis of the simulation is how to simulate the wave source of phased array, how to apply the load and where to apply the load. The experimental results obtained by using TOFD method are in good agreement with the simulation results. From another point of view, it is feasible to use the simulation method to analyze the test results. The accuracy of wave amplitude is not high in the simulation results of traditional detection methods, but the echo time is only measured by using ultrasonic TOFD detection method, which makes up for this defect, and the two methods complement each other. The comparison between the simulation results and the experimental results shows that this method is effective.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB553

【参考文献】