Abstract
Curvatures in mode shapes and operating deflection shapes have been extensively studied for vibration-based structural damage identification in recent decades. Curvatures of mode shapes and operating deflection shapes have proved capable of localizing and manifesting local effects of damage on mode shapes and operating deflection shapes in forms of local anomalies. The damage can be inversely identified in the neighborhoods of the anomalies that exist in the curvatures. Meanwhile, propagating flexural waves have also been extensively studied for structural damage identification and proved to be effective, thanks to their high damage-sensitivity and long range of propagation. In this work, a baseline-free structural damage identification method is developed for beam-like structures using curvature waveforms of propagating flexural waves. A multi-resolution local-regression temporal-spatial curvature damage index (TSCDI) is defined in a pointwise manner. A two-dimensional auxiliary TSCDI and a one-dimensional auxiliary damage index are developed to further assist the identification. Two major advantages of the proposed method are: (1) curvature waveforms of propagating flexural waves have relatively high signal-to-noise ratios due to the use of a multi-resolution central finite difference scheme, so that the local effects of the damage can be manifested, and (2) the proposed method does not require quantitative knowledge of a pristine structure associated with a structure to be examined, such as its material properties, waveforms of propagating flexural waves and boundary conditions. Numerical and experimental investigations of the proposed method are conducted on damaged beam-like structures, and the effectiveness of the proposed method is verified by the results of the investigations.
Highlights
A propagating flexural wave of a beam-like structure can be described by w( x, t), which is a function of two variables, including the spatial position x and time t
High δl −r,8 values can be observed in the neighborhood of the damage and they correspond to changes in curvature waveforms caused by the damage
Multi-solution auxiliary temporal-spatial curvature damage index (TSCDI) δr with r = 8, i.e., δ8, associated with δl −r,8 with ξ = 5%, ξ = 10% and ξ = 15% are shown in Figure 4d–f, respectively, and the locality and extent of the damage can be identified based on the three δ8
Summary
When local damage occurs to a structure, its local stiffness and/or mass will be quantitatively changed [1,2,3,4]. Vibration characteristics of the structure, such as natural frequencies, mode shapes and operating deflection shapes, will be quantitatively changed. The changes in natural frequencies are considered global, as they can be estimated with a few measurements of frequency response functions of the structure, which can correspond to excitation and response points away from the damage [5,6]. The changes in mode shape and operating deflection shapes are considered local. The reason for this is that effects of the damage on the mode shapes and operating deflection shapes can be reflected when the locality of the damage falls within a measurement grid of the mode shapes and operating deflection shapes. The damage cannot be identified and such identification results are considered false-positives
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
