發(fā)布時間：2018-02-13 14:01

  本文關鍵詞： 管結構 導波 疊前逆時偏移 損傷識別　出處：《哈爾濱工業(yè)大學》2015年碩士論文　論文類型：學位論文

【摘要】：在現(xiàn)代工業(yè)中管道結構發(fā)揮著不可替代的作用,管結構的損傷與破壞會導致嚴重的工程事故及重大經(jīng)濟損失,因此對管道結構進行健康監(jiān)測與損傷識別十分必要。在諸多無損檢測方法中,基于超聲導波的無損檢測方法由于其快捷、造價低且適應大范圍檢測等優(yōu)點而受到廣泛關注。本文針對金屬圓管中的裂縫損傷,采用基于導波理論和疊前逆時偏移的方法對其進行損傷成像。本文中首先給出了各向同性空心圓管中導波的頻散特征方程,對三種沿軸向傳播的導波模態(tài)的基本傳播特性進行了分析,并根據(jù)簡正模態(tài)展開法探討了在局部非軸對稱荷載激勵下導波的幅值大小及位移場分布;其次,介紹了疊前逆時偏移方法的基本原理,對扭轉波在各向同性金屬管中的波動進行了建模。最后,試驗研究了d31型和d36型兩種壓電晶片環(huán)形陣列對圓管上裂縫損傷的檢測,應用數(shù)值模擬技術實現(xiàn)了波場的逆時偏移過程,然后采用激勵-時間成像條件提取了損傷的成像結果,將成像結果與損傷的實際狀態(tài)進行了對比,并分別分析了縱向模態(tài)和扭轉模態(tài)對裂縫損傷的檢測能力。研究表明,采用疊前逆時偏移的方法,根據(jù)圓管外表面上環(huán)形分布的傳感系統(tǒng)所采集到的反射信號,能夠成功的對圓管上的缺陷進行成像,試驗驗證了該方法對圓管上的裂縫進行成像的有效性和可應用性。
[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.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U178

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本文編號：1508325