Guided Wave Based Structural Damage Detection And Localization

Civil structures and ?eld devices are prone to structural aging and fatigue effects in the course of the long period of environmental erosion. In the case of structural damage, requirement of durable performance and reliability of the structure can not be met,thus imposing direct thread to the safety and property of citizens, as well as industrial products. Therefore it is of vital importance to introduce health monitoring methods to detect, assess damage status and assure the safe working condition of structure.Apparently, surveillance of large civil structures or complex ?eld deployment device purely with manpower is not cost-e?cient, not only that it demands a lot of manpower and resources, but also may that human beings are prone to have blind spots when it comes to complex structure. Thus, intelligent, standardized testing attracts more and more attention of the industry.Recent years have witnessed the emergence of smart materials and the rapid development of computer science and communications technology for smart sensors, which laid the foundation of networked intelligent health monitoring systems. Among them,the cheap, small piezoelectric wafers ?t for large-scale deploying in structures and can play the role of intelligent sensing devices for active structural testing. Ultrasonic guided wave testing, as one of the commonly used nondestructive structural testing techniques, takes the bene?t of wave features such as long propagating ability and sensitivity to damage. By analyzing the high-frequency wave signals collected by sensors adhering to the surface or embedded in the interlayer of the structure, the location,shape and even severity of the damage can be ?gured out.In this thesis, we focus on ultrasonic guided wave testing theory, method, structural damage detection, localization and the relevant signal processing issues.1. Ultrasound guided wave propagation characteristics in the structure, wave interacting with the damage and formulation of guided wave propagation model.2. Multi-modal characteristics of guided wave, mode detection and separation using spectral clustering in frequency-wavenumber domain.3. Construct a model based on the basis of guided wave propagation. Use a ?nite element method to approximate the original model to balance the computation complexity and accuracy, so as to save computation resource.4. Guided wave signal based damage localization algorithm. Based on the idea of compressed sensing, sparse constraint is forced when solving the underdetermined inverse problem and achieve damage localization ?nally.