基于三角时差技术的二维板声发射源定位方法研究

发布时间：2018-06-24 03:13

本文选题：声发射 + 声源定位　；参考：《吉林大学》2017年硕士论文

【摘要】：材料的结构损伤较为常见,且在很多情况下会导致设备的性能降低,甚至带来安全隐患。声源定位作为声发射技术的目的之一,在损伤早期可以通过声源定位发现受损位置,避免或减少这类事故的发生。二维板类结构在汽车机身、液体储罐、航空设备、压力容器等各类结构中应用广泛,但是近些年来一些新型工程材料如纤维增强复合固体材料的使用,传统的时差法无法实现各向异性二维板类结构的声发射源定位,人们对于各向异性材料的声发射源定位的研究尚缺少认识。为此,本文开展了不受各向异性限制的基于新三角时差技术的二维板声发射源定位方法研究。本文针对二维板类结构,回顾声发射发展历程,从声发射理论知识入手,到波的传播特性、信号处理和仪器系统等,展开声发射源定位方法的研究工作,着重解释新三角时差技术的原理和实现,并在新三角时差技术基础上提出了一种“z”形四探头的定位方法,不仅具有三角时差技术不受各向异性的限制、无需知道板内声速分布、快速简易、传感器数量较少的优点,同时缩小了定位面积,为工程上声发射定位方法提供了一种可行的技术.同时在实验室进行实验验证的过程中,提出利用单通道的脉冲信号发射接收仪、示波器和2个超声波传感器实现声发射源定位实验方法。目前大多数高校实验室在大学物理实验中采取的归一正方形法、任意平面三角形算法等声源定位方法,要求定位的二维板必须为各向同性的,且需要提前知道板内的波速等信息.实验通常采用断铅进行模拟声发射源,用至少4个接收传感器及多通道采集设备完成实验,实验成本较高,计算过程复杂需要专业的计算软件,不适合普及及对物理问题的深入理解。这些问题严重制约了声发射技术在板状结构损伤定位中的深入应用。实验结果表明“z”形四探头技术和新三角时差技术都可以快速、较准确的定位出声源所在位置,新三角时差技术精确度较高,“z”形四探头定位技术占用的面积较小。对于工业等领域的无损检测声发射定位技术,贡献了一种应用更为广泛,不受各向异性限制、需要较少的超声波传感器探头、能够快速对二维板类声发射源定位的方法。
[Abstract]:Structural damage of materials is more common, and in many cases will lead to equipment performance degradation, and even bring safety risks. As one of the aims of acoustic emission technology, sound source location can be detected by sound source location in the early stage of injury to avoid or reduce the occurrence of such accidents. Two-dimensional plate structure is widely used in automobile fuselage, liquid storage tank, aeronautical equipment, pressure vessel and so on. But in recent years, some new engineering materials such as fiber reinforced composite solid materials have been used. The traditional time difference method can not realize the acoustic emission source localization of anisotropic two-dimensional plate structure, but the research on acoustic emission source localization of anisotropic materials is still lack of understanding. In this paper, the localization method of two dimensional plate acoustic emission source based on the new triangular time difference technique without anisotropic constraints is studied in this paper. This paper reviews the development of acoustic emission (AE), starting with the theory of acoustic emission (AE), the characteristics of wave propagation, signal processing and instrument system, etc., in this paper, the research of acoustic emission source location method is carried out. This paper mainly explains the principle and realization of the new triangular time difference technology, and puts forward a "z" shape four-probe positioning method based on the new triangular time difference technology, which has not only the limitation of the anisotropy of the triangular time difference technology. There is no need to know the distribution of sound velocity in the plate, which is fast and simple, and the number of sensors is less. At the same time, the location area is reduced, which provides a feasible technique for acoustic emission localization in engineering. At the same time, in the process of experimental verification in the laboratory, an experimental method of acoustic emission source location using single channel pulse signal transmitter receiver, oscilloscope and two ultrasonic sensors is put forward. At present, most university laboratories adopt the normalized square method, arbitrary plane triangle algorithm and other sound source localization methods, which require the two-dimensional plate to be isotropic. And need to know in advance the wave velocity and other information in the plate. The experiment usually uses lead broken lead to simulate acoustic emission source, and at least 4 receiving sensors and multi-channel acquisition equipment are used to complete the experiment. The cost of the experiment is high and the calculation process is complicated, which requires professional calculation software. It is not suitable for popularization and deep understanding of physical problems. These problems seriously restrict the deep application of acoustic emission technology in plate structure damage location. The experimental results show that both the "z" shape four-probe technique and the new triangular moveout technique can locate the sound source accurately, the accuracy of the new triangular time-difference technique is higher, and the area occupied by the "z" shape four-probe positioning technique is smaller. For the nondestructive testing (NDT) acoustic emission localization technology in industry and other fields, it contributes a more widely used method, which is not restricted by anisotropy, and requires less ultrasonic sensor probe, which can quickly locate the acoustic emission source of two-dimensional plate.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O42

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