Detecting damage through the processing of dynamic shapes measured by a PSD-triangular laser sensor

Abstract

There exist several studies in the literature which have shown the potentiality offered by certain vibration-based techniques aimed at detecting damage in structural systems. In all these existing techniques noise (distributed and/or outliers) plays a significant role and can make the difference between a successful or an unsuccessful application. In spite of such a mentioned remarkable influence, the studies aimed at investigating the influence of noise on the success of the techniques are not as rich in experimental details as they are in numerical simulations. In this work an extensive set of experiments aimed at evaluating the feasibility of certain diagnosing techniques is provided. This work should also be considered as the experimental validation of certain analytical and numerical simulations carried out in the past [Gentile, A., Messina, A., 2003. On the continuous wavelet transforms applied to discrete vibrational data for detecting open cracks in damaged beams. International Journal of Solids and Structures 40, 295-315;Messina, A., 2004. Detecting damage in beams through digital differentiator filters and continuous wavelet transforms. Journal of Sound and Vibration 272, 385-412] within the frame of real measurements based on a particular laser technology; in addition, the mentioned validating experiments illustrate certain peculiarities not shown in the past, and, finally, valuable benchmarks are provided for testing future diagnosing techniques in numerical simulations. The experimental set-up consists of both commercial and electronic circuits appropriately designed and realized, whose significance, in the measuring system is accurately described in order to increase the signal/noise ratio of the dynamical measurements.

Dynamic Identification Techniques to Numerically Detect the Structural Damage

“…The measured mode shapes with difficulty are regular curves, so the computed modal curvature will show irregular variation: there is the need to smooth the measured mode shapes by using curve fitting analysis before applying Eq.(8). The mode shape measurement has been utilized also to experimentally locate the position of a damage using the dynamic shape measurement, such as in [28].…”

A Crack Identification Method for Bridge Type Structures under Vehicular Load Using Wavelet Transform and Particle Swarm Optimization

“…Generally, SD at points close to beam ends is higher. This is because the curvature of vibration modes around the beam ends is small for simply supported beam [26]. Thus cracks close to beam ends do not have much effect on the dynamic response of the beam.…”

Refinements of damage detection methods based on wavelet analysis of dynamical shapes

“…open symmetrical crack, without considering the effect of rotatory inertia). As far as experimental dynamical shapes are concerned, the measurements obtained as illustrated in Trentadue et al (2007) are taken into account. In particular, as far as these latter data are concerned, it is stressed here that a slightly improved method (Messina and Albanese, 2008) has been applied in order to extract dynamical shapes without outliers.…”

“…In this regard, several researchers have recently followed this approach by using several approaches (e.g. Yuen, 1985;Pandey et al, 1991;Ratcliffe, 1997;Ratcliffe and Bagaria, 1998;Wang and Deng, 1999;Hong et al, 2002;Messina, 2002, 2003;Loutridis et al, 2004;Messina, 2004;Han et al, 2005;Yoon et al, 2005;Rucka and Wilde, 2006a,b;Trentadue et al, 2007) and among them the application of wavelet analysis is one of the most investigated subjects. The present context regards the wavelet analysis applied in the guise of CWT as established in Gentile and Messina (2003) and Messina (2004).…”

“…This work introduces two different methods aimed at reducing the so called border distortion phenomenon which can be easily and immediately applied to real data; the methods are characterised by different levels of complexity and their successful behaviour can be interpreted in the light of the equivalencies between CWT and differentiator FIR filters Messina (2004); all the analytical and experimental tests are based on a highly redundant number of points (a few hundreds) in order to stay in line with the past investigations (Gentile and Messina, 2003;Messina, 2004;Trentadue et al, 2007). The methods presented in this work are discussed in comparison with those already proposed in the open literature whenever existing and, finally, it is believed that all findings herein illustrated are applicable in all structures which allow a multi-grid measurability of dynamical shapes.…”