基于超声导波的复杂结构微-小损伤识别技术研究

Barely visible damage (BVD), such as fatigue and micro and small crack, detection for complex structures is one of the difficulties in the practical commercial application of ultrasonic based structural health monitoring techniques. The project will investigate the micro and small damage detection for complex and key components of mechanical equipments and large scale structures, which will be based on the linear and nonlinear characteristics of ultrasonic guided waves with the micro and small defects in the components. Five key problems will be studied in the projects, namely, 1) propagation characteristics of nonlinear ultrasonic guided waves in complex structures, 2) dynamics model and simulation of micro and small damages, 3) damage detection methods based on mode conversion and nonlinear characteristics of guided waves, 4) signal processing methods for non-stationary guided wave signals with feeble damage caused signal features, and 5) specimen manufacturing and experimental research. Working condition and experiment of mechanical equipments and large scale structures will also be considered in the project, to explore the theoretical analysis, model and simulation, and experimental verification in BVD detection for complex structures. Purpose of the project is to inspect the structural damage at the early stage for timely detection and repair. Outcomes of the project will lead to novel and practicable technologies for real-time structural health monitoring and integrity assessment with higher accuracy, and will significantly improve operation safety and reduce maintenance costs.

诸如结构疲劳和微小裂纹等不可见损伤的检测难题是基于导波的主动在线结构健康监测技术工程实用化的主要因素之一。本项目将以机械装备和工程结构中复杂关键构件为研究对象，应用超声导波与结构微-小损伤耦合的线性和非线性效应，对超声导波在复杂构件中传播的非线性效应、微-小损伤的动力学建模与仿真、基于导波模式转换和非线性导波的损伤识别、微弱超声导波信号的特征提取与损伤识别方法、以及试件模拟与试验研究五个方面开展研究。考虑机械装备和工程结构的工况和服役环境，探索将线性和非线性超声导波用于复杂构件不可见损伤识别的理论分析、建模仿真和试验验证问题。以期在结构损伤出现早期实时监测其健康状况，并及时采取必要的维护措施。研究过程将充分重视学科交叉与渗透，在现有申请者课题组研究成果的基础上，研究开发自主创新的理论和技术。本项目的研究对推动基于导波的结构健康监测技术的发展具有重要的理论意义和工程实用价值。

超声导波应用于主动在线结构健康监测技术的过程中，必须考虑到结构复杂性，损伤的不可见，基准信号不确定等制约因素。本项目以机械装备和工程结构中复杂关键构件为研究对象，应用超声导波与结构微-小损伤耦合的线性和非线性效应，对超声导波在复杂构件中传播的非线性效应、微-小损伤的动力学建模与仿真、基于导波模式转换和非线性导波的损伤识别、微弱超声导波信号的特征提取与损伤识别方法、以及试件模拟与试验研究等方面进行了深入的研究。. 通过对以上内容的研究，以结构中非线性谐振波的时频域分析，超声导波的无基准监测和导波信号特征提取信号处理方法等方面为对象，得到了如下几个方面的成果。考察了两列不同频率声波混叠生成的谐振波在时域上的特点；研究了激励时间差对混叠生成的谐振波响应的影响；分析了互成角度波束混叠方法中相控阵的参数化过程；利用超声导波对工字梁中的损伤进行定位；发展了基于超声导波传播特性的高铁轮轴的结构健康监测技术；改进了板结构中无基准的损伤识别方法及成像技术；探究了基于导波研究燃气轮机拉杆转子接触特性的可能性；考虑了充液条件下的管道损伤识别技术的应用；发展了基于改进经验小波变换的噪声与非稳态信号处理方法；最后改进调频小波变换在瞬时频率估计中应用。. 探索了线性和非线性超声导波用于复杂构件不可见损伤识别的理论分析、建模仿真和试验验证问题。研究过程充分重视学科交叉与渗透，开发自主创新的理论和技术。本项目的研究对推动基于导波的结构健康监测技术在工程实践中的发展具有重要的理论意义和工程实用价值。

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