Hybrid monitoring, diagnostics and prognostics on machines and structures

振动是结构和机械损伤和失效的最重要的来源。在现代工程中，虽然静力载荷已经通过先进的计算和有限元方法得到了深入的研究和解决，但非线性、不确定性和非平稳性的动力问题尚未得到明确的解决，特别是对于现有的机构和结构。理解和预测这种现实系统动态行为的最佳方法是进行实验分析、诊断和预测。本实验研究的核心是模态分析。在过去的二十年里，模态分析的知识已经发展到“运行”水平，考虑到系统的实际结构和力学条件及其运行载荷。因此，运行模态分析（OMA）面临的挑战是运行过程中几何形状、质量和刚度的变化、现有的机械和结构损伤、局部模态、未知的谐波和随机激励以及高噪声水平。

Vibrations are the most critical source of structural and mechanical damage and failure. In modern engineering, while static loading has been thoroughly investigated and resolved by advanced computing and finite element methods, dynamic problems with nonlinearities, uncertainty and non-stationarity have not yet been solved explicitly, especially for existing mechanisms and structures. The best approach to understand and predict the dynamic behavior of such real-life systems is to conduct experimental analysis, diagnostics and prognostics. The core of this experimental investigation is modal analysis. Over the past two decades, knowledge of modal analysis has developed to the “in operation” level, taking into account actual structural and mechanical conditions of systems and their operating loads. Consequently, the challenges faced in operational modal analysis (OMA) are the variations in geometry, mass and stiffness during operation, the existing mechanical and structural damage, local modes, unknown harmonic and random excitations, and high noise levels. The research program proposed is designed to study and elucidate the problems above using the finite element method, time series vector autoregressive (VAR) model, Kalman filter and artificial intelligence. The objective of the program is to develop projects to resolve research issues and spawn innovations in OMA for the analysis and monitoring of existing mechanical systems subject to non-stationary vibrations. Through initial researches on stationary and short-time non-stationary vibrations, this method has demonstrated extraordinary performance and led to efficient applications in terms of precision, stability and robustness. Moreover, this methodology supports the handling of a large number of sensors and has huge potential for the development of advanced functionalities. Under this program, various research topics will be explored on non-stationary vibrations: optimization of sensor number and location, localization and estimation of damage; identification of damping; updating the finite element model; development of a time-frequency-damping technique for the detection of damage initiation and propagation; and adaptive model updating for signal processing. A new technique is proposed called “hybrid operational monitoring” (HOM), which combines operational modal monitoring and finite model updating. On this basis, a diagnostic-prognostic-health monitoring technology is developed for machine and structure management, prediction and maintenance. The program will focus on applications for different machines, e.g., rotating machines (hydraulic turbines and wind turbines with harmonic excitations) and processing machines (grinding robots with variations in geometry and stiffness), and will consider specific operating conditions and the various types of damage.