<title>Identifying damage in plates by analyzing Lamb wave propagation characteristics</title>

Abstract

The goal of this paper is to discuss different data interpretation concepts for structural health monitoring based on Lamb wave propagation. Surface-mounted piezoelectric transducers are used as wave emitters and receivers. The waves emitted interact with discontinuities and experience a change in their propagation characteristics when damage is generated. By comparing sensor signals collected before and after damage has been generated, the condition of the structure can be determined. Two approaches are proposed for characterizing the damage. The initial approach analyzes only the first wave packet reflected at the damage and is based on a simple time-of-flight analysis in conjunction with a geometric method. The size of the damage can be estimated with this technique by using several pairs of piezoelectric sensors. The second technique considers additional modes and is based in particular on the presence of modeconversion processes. This technique offers the potential for enhancing measurement accuracy. An estimation of the size and location of the damage becomes possible with just three piezoelectric sensors. It has been found that, in practice, the superposition of wave packets represents one of the main problems in realizing this approach. The decomposition of superimposed wave packets is investigated using wavelet transform and the pulse compression technique. It is shown that noise and dispersion represent a major drawback, hence rendering signal analysis distinctly more difficult.

Structural Damage Location with Fiber Bragg Grating Rosettes and Lamb Waves

“…For the whole process of damage identification (i.e., detection, location, severity, classification and prediction of damage) most of the work published is on the detection process. Major contributions to the location of damage include [7]. Within this study, however, the location of damage using Lamb waves is studied in detail.…”

Smart sensing, monitoring, and damage detection for civil infrastructures

“…2 have been widely used in structural dynamics applications because they are lightweight, robust, inexpensive, and come in a variety of forms ranging from thin rectangular patches to complex shapes . Based on this functionality, piezoelectric sensors have been the most extensively used for both impedance-based damage detection (Giurgiutiu and Rogers, 1997;Tseng et al, 2000;Zagrai and Giurgiutiu, 2001;Park et al, 2003;Park et al, 2006a;Mascarenas et al, 2007;Overly et al, 2007;Min et al, 2010; and guided waves-based damage detection methods (Monkhouse et al, 1997;Keilers and Chang, 1995;Diaz Valdes and Soutis, 2000;Osmont et al, 2001;Kehlenbach and Das, 2002;Sohn et al, 2003Sohn et al, , 2009Kim and Sohn, 2006;Park et al, 2006b;Raghavan and Cesnik, 2007;An et al, 2009). With the recent advances of signal processing techniques and the improvement of hardware including MEMS (MicroElectroMechanical Systems) technology and wireless data transmission, piezoelectric sensors become more attractive in on-line SHM as well as non-destructive testing.…”

Detection of crack in thin cylindrical pipes using piezo-actuated Lamb waves

“…The use of ultrasonic guided waves for non-destructive evaluation (NDE) of structures is effective due to their long propagation range as stated in many published literature such as Alleyne and Cawley (1992), Park et al (1996), Monkhouse et al (2000), Quek et al (2001), Lowe et al (2002a,b), Kehlenbach and Das (2002), and Tua et al (2004a,b). However, the guided wave must be selectively generated to effectively locate and quantify the defect (Ghosh et al, 1998;Lowe et al, 2001a,b;Jin et al, 2004;Tua et al, 2004a).…”