工程层状结构中的弹性波及其应用

发布时间：2018-10-14 19:57

【摘要】：层状结构是工程中普遍存在的结构类型,层状结构中的界面是工程中的关键部位,界面粘接质量的好坏直接影响着工程的运营年限和使用安全。因此,界面粘接质量的检测,是加强工程后续施工质量控制的重要保障,也是消除沉降、漏水、坍塌等安全隐患的必要手段,更是确保工程设计使用寿命的有效步骤。工程中常使用的检测方法是弹性波检测法,也是检测层介质界面加固粘接质量比较有效的无损检测方法,研究各因素对弹性波在工程的层状结构中的传播效应的影响,对合理设计出针对工程实际问题的检测方案具有重要的意义。本文的主要研究内容及结果如下:(1)层介质材料波阻抗比对弹性波在工程层状结构中的传播影响。采用ANSYS有限元软件的瞬态动力学分析模块,分别建立介质置换层材料类型为混凝土、硬质岩、软质岩、泥岩的工程层状结构有限元模型。以界面粘接质量好坏进行划分,分别构造完整界面和缺陷界面模型,并进行求解分析,结果表明:异质性条件下相比均质性条件下,反射信号突出,并随介质波阻抗比降低愈加明显;因为缺陷的存在,使得应力波以扰动形式绕射传播到缺陷下表面,进而在内层介质中传递能量,而当介质波阻抗差异面明显时,透射能量减少,在缺陷两侧的反射能量增强。(2)界面粗糙度对弹性波在工程层状结构中的传播影响。采用ANSYS有限元软件的瞬态动力学分析模块,分别建立以曲率为0、0.25、0.5、0.75、1来表征不同界面粗糙度的两层层状结构有限元模型。以界面形貌差异进行划分,分别构造出存在不同界面缺陷的模型,并进行求解和分析,结果表明:当界面出现复杂形貌并随粗糙度逐渐增加的情况下,多次反射次数逐渐减少、时间逐渐减短,当粗糙度达到一定程度时,开始出现反射波形,说明形成延时反射信号不一定是因为检测对象存在孔洞等缺陷,而只是界面粗糙程度较高导致。(3)界面缺陷对弹性波在工程层状结构中的传播影响。通过有限元软件ANSYS构造钢筋混凝土三层层状结构,首先为了判断缺陷尺寸对弹性波在其中传播的影响,分别建立了缺陷横向尺寸变化对比的四组模型和缺陷纵向尺寸变化对比的四组模型,其次为了判断缺陷定位相对信号接收位置对弹性波传播影响,分别建立三组不同缺陷定位模型,并进行求解分析,结果表明:随着缺陷尺寸横向长度加长,反射信号波形初次反射波起跳时间提前,缺陷位置距离接收传感器位置越远,频谱图中高于共振主频的频率对应幅值增加,反射能量加强。通过本文的研究,对于采用弹性波法检测工程层状介质界面粘接质量的实施和数据分析具有一定的参考及指导意义。
[Abstract]:Layered structure is a common type of structure in engineering. The interface of layered structure is the key part in engineering. The quality of interface bonding directly affects the operation life and safety of the project. Therefore, the inspection of interface bonding quality is not only an important guarantee to strengthen the quality control of subsequent construction, but also a necessary means to eliminate the hidden dangers of settlement, water leakage, collapse and so on. It is also an effective step to ensure the service life of engineering design. The commonly used detection method in engineering is elastic wave detection method, and it is also an effective nondestructive testing method to detect the bonding quality of layer dielectric interface. The influence of various factors on the propagation effect of elastic wave in engineering layered structure is studied. It is of great significance to reasonably design the detection scheme for practical engineering problems. The main contents and results of this paper are as follows: (1) the influence of wave impedance ratio of layered materials on the propagation of elastic waves in engineering layered structures. By using the transient dynamic analysis module of ANSYS finite element software, the finite element model of engineering layered structure is established, which the material types of media replacement layer are concrete, hard rock, soft rock and mudstone. According to the quality of interface bonding, the complete interface model and defect interface model are constructed, and the results show that the reflected signal is prominent under heterogeneity compared with homogeneity. Because of the defect, the stress wave diffracted to the lower surface of the defect, and then transferred energy in the inner medium, and when the difference surface of the dielectric wave impedance was obvious, the stress wave diffracted to the lower surface of the defect, and when the difference surface of the dielectric wave impedance was obvious, the stress wave diffracted to the lower surface of the defect. The transmission energy decreases and the reflection energy increases on both sides of the defect. (2) the effect of interface roughness on the propagation of elastic waves in engineering layered structures. The transient dynamics analysis module of ANSYS finite element software is used to establish the finite element model of two-layer layered structure with curvature of 0.250.250.5and 0.75-1 to characterize different interfacial roughness. According to the difference of interface morphology, the models with different interface defects are constructed, and solved and analyzed. The results show that the number of multiple reflections decreases gradually when the complex morphology of the interface appears and the roughness increases gradually. The time decreases gradually, when the roughness reaches a certain degree, the reflection waveform begins to appear, which indicates that the formation of the delayed reflection signal is not necessarily due to the defects such as holes in the detection object. It is only due to the high degree of interface roughness. (3) the effect of interface defects on the propagation of elastic waves in engineering layered structures. In order to determine the effect of defect size on the propagation of elastic wave, the finite element software ANSYS is used to construct a reinforced concrete three-story layered structure. In order to judge the influence of the position of defect location on the propagation of elastic wave, four groups of models are established to compare the change of transverse dimension of defect and the change of longitudinal dimension of defect. Three groups of different defect location models were established and solved. The results show that with the length of the defect dimension lengthening, the initial jump time of the reflected signal waveform is advanced, and the defect position is farther away from the receiving sensor position. The corresponding amplitudes of the frequencies above the main resonance frequency in the spectrum are increased and the reflection energy is strengthened. Through the research in this paper, it has certain reference and guiding significance for the application and data analysis of testing the interface bonding quality of engineering layered medium by using elastic wave method.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43;TB302.5

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