Abstract
As an impact-source-localization technique, Lamb waves are commonly used to detect low-velocity impact in composite structures. However, the performance of Lamb waves is susceptible under deformation conditions. In this paper, a novel approach combined the Toeplitz approximation method (TAM) and multiple-signal classification (MUSIC) (TAM-MUSIC) to improve impact-source-localization (angle and distance in polar coordinates) accuracy under deformation conditions. The method divided a two-dimensional search of direction and distance into two one-dimensional searches. The impact direction was calculated by the TAM, which was introduced into the steering vector of MUSIC to estimate the distance by scanning the whole monitoring area. An epoxy laminate plate experiment showed that the phase and amplitude of uniform linear-array signals had different average plate curvature that led to poor impact-source-localization accuracy using the MUSIC method. TAM provided high-resolution direction-finding capability, suitable for the pretreatment of Lamb waves. Results showed that the present method, with a small amount of computation and low memory requirement, had higher location-estimation accuracy than that of traditional methods under deformation conditions.
Highlights
Compared with common metallic materials, composite materials have properties that increase their applicability in engineering structures [1]
Many localization methods based on Lamb waves using the sparse-sensor array have been proposed for structural-health monitoring (SHM), including a triangulation technique [10], four-point arch localization [11], and a time-reversal imaging method [12]
Schmidt et al [15] described the multiple-signal-classification (MUSIC) method, based on the eigenvalue decomposition of the sample-covariance matrix, as a breakthrough space-spectrum algorithm to calculate the direction of arrival (DOA)
Summary
Compared with common metallic materials, composite materials have properties that increase their applicability in engineering structures [1]. Many localization methods based on Lamb waves using the sparse-sensor array have been proposed for SHM, including a triangulation technique [10], four-point arch localization [11], and a time-reversal imaging method [12] These methods are readily influenced by the orthotropic performance of the composite during application. Yang et al [17] used the MUSIC method and time delay of arrival to calculate direction and distance to locate the impact source in a plate He et al [18] developed an imaging algorithm using time-reversal operator decomposition and the Sensors 2020, 20, 3151; doi:10.3390/s20113151 www.mdpi.com/journal/sensors.
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