基于叠前逆时偏移方法的圆管损伤识别

发布时间：2018-02-13 14:01

本文关键词： 管结构导波叠前逆时偏移损伤识别　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：在现代工业中管道结构发挥着不可替代的作用,管结构的损伤与破坏会导致严重的工程事故及重大经济损失,因此对管道结构进行健康监测与损伤识别十分必要。在诸多无损检测方法中,基于超声导波的无损检测方法由于其快捷、造价低且适应大范围检测等优点而受到广泛关注。本文针对金属圆管中的裂缝损伤,采用基于导波理论和叠前逆时偏移的方法对其进行损伤成像。本文中首先给出了各向同性空心圆管中导波的频散特征方程,对三种沿轴向传播的导波模态的基本传播特性进行了分析,并根据简正模态展开法探讨了在局部非轴对称荷载激励下导波的幅值大小及位移场分布;其次,介绍了叠前逆时偏移方法的基本原理,对扭转波在各向同性金属管中的波动进行了建模。最后,试验研究了d31型和d36型两种压电晶片环形阵列对圆管上裂缝损伤的检测,应用数值模拟技术实现了波场的逆时偏移过程,然后采用激励-时间成像条件提取了损伤的成像结果,将成像结果与损伤的实际状态进行了对比,并分别分析了纵向模态和扭转模态对裂缝损伤的检测能力。研究表明,采用叠前逆时偏移的方法,根据圆管外表面上环形分布的传感系统所采集到的反射信号,能够成功的对圆管上的缺陷进行成像,试验验证了该方法对圆管上的裂缝进行成像的有效性和可应用性。
[Abstract]:Pipeline structure plays an irreplaceable role in modern industry. The damage and destruction of pipe structure will lead to serious engineering accidents and major economic losses. Therefore, it is necessary to carry out health monitoring and damage identification for pipeline structures. Among the many nondestructive testing methods, the ultrasonic guided wave based nondestructive testing method is very fast. The advantages of low cost and suitable for large-scale detection have attracted wide attention. In this paper, the crack damage in metallic circular pipes is studied. Based on the theory of guided wave and the method of prestack inverse time migration, the damage imaging is carried out. In this paper, the dispersion characteristic equation of guided wave in an isotropic hollow tube is first given. The basic propagation characteristics of three kinds of guided wave modes propagating along axial direction are analyzed, and the amplitude and displacement distribution of guided waves under the excitation of local non-axisymmetric loads are discussed according to the normal mode expansion method. The basic principle of prestack inverse time migration method is introduced, and the wave of torsional wave in isotropic metal tube is modeled. Finally, two kinds of piezoelectric wafer ring arrays, d31 and d36, are experimentally studied to detect the crack damage on a circular tube. The inverse time migration process of the wave field is realized by numerical simulation technique. Then the damage imaging results are extracted by using the excitation-time imaging condition, and the imaging results are compared with the actual state of the damage. The ability of longitudinal mode and torsional mode to detect crack damage is analyzed respectively. The results show that the method of prestack inverse time migration is used to measure the reflected signals collected by the annular sensor system on the outer surface of the pipe. The defect on the circular pipe can be successfully imaged, and the experimental results show that the method is effective and applicable to the cracks on the pipe.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U178

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