钢筋混凝土构件损伤检测中的声发射机理及特性研究

发布时间：2018-06-13 11:38

本文选题：钢筋混凝止构件 + 声发射特性　；参考：《江苏大学》2015年博士论文

【摘要】：针对混凝土构件损伤检测中声发射的复杂性,基于弹性波理论,采用破坏分解分析法对钢筋混凝土构件破坏过程中的损伤机理进行实验研究；采用“参数分析”与“波形分析”的杂交法分析构件破坏过程中的声发射特征,并对波形进行Hilbert-Huang变换得到声发射信号的三维能量谱,进而提取声发射信号中的最大瞬时幅值及其对应的特征瞬时频率,建立了相应的检测评估钢筋混凝土构件损伤的声发射测试准则。本文的主要研究可分为以下内容：针对混凝土构件的常见开裂破坏过程,基于弹性波理论,采用矩张量模拟声发射源,建立声发射的有限元数值模型,研究声源激发、超声波传播特征及信号接收,以揭示声发射源的力学机理,根据超声波的传播特性建立了声发射损伤检测的传感器设置原则。构建一种由基本破坏到复杂破坏的研究策略,实验研究了若干个基本破坏模式(包括素混凝土开裂破坏、钢筋拉伸破坏、钢筋与混凝土的粘结滑移破坏等)中的声发射机理及特性。提出了兼具“参数分析”快速、实时和“波形分析”全面、准确等优势的杂交分析方法,实现对声发射信号的量化表征。采用具有自适应特性的Hilbert-Huang变换(HHT)分析波形获得声发射信号的三维能量谱,确定了两个能够充分表征声源强度和性质的声源最大瞬时幅值及其对应的特征瞬时频率的特征参量,并据此两特征参量建立甄别不同声发射源(损伤)的机制。基于基本破坏形式下若干个典型损伤的声发射特性,对钢筋混凝土构件的声发射信号进行了研究,建立了其整体破坏过程与基本破坏试验的关系,提出了钢筋混凝土构件声发射损伤类型识别判据。并基于此,对纯弯曲状态下普通钢筋混凝土梁的破坏过程进行了损伤识别,获得了能够直观反映损伤状态的整体时-频-能量分布变化图,实现了对钢筋混凝土梁损伤状态的定量评价。利用数字图像相关(DIC)方法对声发射测试结果进行了验证。本文的工作充分说明参数-波形杂交分析法能够有效地应用于钢筋混凝土结构的损伤检测。利用HHT时频能量谱量化分析方法可对钢筋混凝土结构进行定量损伤评价,进一步拓展到土木工程领域的各种损伤类型,可最终实现实际工程结构的在线监测,从而实现结构破坏的早期预警、定量评估及寿命预测。
[Abstract]:Aiming at the complexity of acoustic emission in damage detection of concrete members, based on elastic wave theory, the damage mechanism of reinforced concrete members during failure is studied experimentally by using failure decomposition analysis method. The hybrid method of "parameter analysis" and "waveform analysis" is used to analyze the acoustic emission characteristics in the process of component failure, and the three-dimensional energy spectrum of acoustic emission signal is obtained by Hilbert-Huang transform. Then the maximum instantaneous amplitude of acoustic emission signal and its corresponding characteristic instantaneous frequency are extracted and the corresponding acoustic emission test criteria are established to detect and evaluate the damage of reinforced concrete members. The main research of this paper can be divided into the following parts: in view of the common cracking and failure process of concrete members, based on elastic wave theory, the acoustic emission source is simulated by moment Zhang Liang, and the finite element numerical model of acoustic emission is established to study the acoustic source excitation. In order to reveal the mechanical mechanism of acoustic emission source, the principle of sensor setting for acoustic emission damage detection is established according to the characteristics of ultrasonic wave propagation and signal receiving. A kind of research strategy from basic failure to complex failure is constructed, and several basic failure modes (including plain concrete cracking failure, reinforcing bar tensile failure) are experimentally studied. The mechanism and characteristics of acoustic emission in the bond-slip failure of steel bar and concrete. A hybrid analysis method with the advantages of "parameter analysis", "real time" and "waveform analysis" is proposed to realize the quantitative characterization of acoustic emission signals. Using Hilbert-Huang transform (HHT) with adaptive characteristics to analyze waveforms to obtain three dimensional energy spectrum of acoustic emission signal, two characteristic parameters of maximum instantaneous amplitude and corresponding characteristic instantaneous frequency of sound source which can fully characterize the intensity and properties of sound source are determined. According to the two characteristic parameters, the mechanism of discriminating different acoustic emission sources (damage) is established. Based on the acoustic emission characteristics of several typical damage in the basic failure form, the acoustic emission signals of reinforced concrete members are studied, and the relationship between the whole failure process and the basic failure test is established. The identification criterion of acoustic emission damage type of reinforced concrete members is proposed. Based on this, damage identification of common reinforced concrete beam under pure bending state is carried out, and the time-frequency energy distribution diagram of the whole beam can reflect the damage state intuitively. The damage state of reinforced concrete beam is evaluated quantitatively. The acoustic emission (AE) test results are verified by digital image correlation (DIC) method. The work of this paper fully shows that the parametric-waveform hybrid analysis method can be effectively applied to the damage detection of reinforced concrete structures. The quantitative damage evaluation of reinforced concrete structures can be carried out by using HHT time-frequency energy spectrum quantitative analysis method, which can be further extended to various damage types in civil engineering field, and can finally realize on-line monitoring of actual engineering structures. Thus, the early warning, quantitative evaluation and life prediction of structural damage can be realized.
【学位授予单位】：江苏大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU375;TU317

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