Transmissibility function-based fault diagnosis methods for beam-like engineering structures: a review of theory and properties

The beam-like structures commonly exist in engineering systems and there are many critical issues relevant to fault diagnosis of those structures. Noticeably, among all other existing methods, transmissibility function-based diagnostic methods, providing much more sensitive damage indexes, are frequently applied and extensively studied, and it is thus meaningful to have a thorough review on most recent advance and related technical difficulties. This paper is, therefore, to present a comprehensive review on this topic for those engineering-oriented beam-like structures, focusing on fundamental theory, critical fault properties and potential applications, respectively. According to different transmissibility function-based features, existing methods are classified into several categories, i.e. general linear transmissibility function, general nonlinear transmissibility function, generalized frequency response function and the second-order output spectrum. With a chain-type multi-degree-of-freedom model with additional connections used for analysing dynamics of beam-like engineering structures, essential topics of these methods including types of transmissibility functions, damage indexes and procedures are discussed in detail. Moreover, the effectiveness, merits and demerits are illustrated by the numerical and experimental results, respectively. It should be noted that some methods discussed here can be readily extended and applied to diagnosis of other plate-like and rotor-like, etc., engineering structures. Apart from fault detection and localization, more sensitive transmissibility function-based damage indicators providing severity and residual life of damaged structures would be further development topics in this area.