In situmechanical characterization of isotropic structures using guided wave propagation

Abstract

Guided waves are widely used in structural health monitoring (SHM). Their behaviour is highly sensitive to the mechanical properties of a structure. The performance of damage detection strategies based on guided waves therefore relies on an accurate knowledge of the mechanical properties. This paper presents an integrated characterization technique that identifies the mechanical properties of isotropic structures, namely the elastic modulus and Poisson’s ratio. The approach is based on a modified version of an imaging algorithm (Excitelet), where mechanical properties, instead of geometrical scattering features, are set as the variables to be identified. The methodology, accuracy, repeatability, and robustness are assessed, first via a finite element model (FEM) and then experimentally for an aluminum plate with attached piezoceramic (PZT) transducers. The plate is instrumented with two PZTs located 15 cm from each other in a pitch–catch configuration, distant enough to ensure proper mode discrimination. The algorithm accuracy and robustness with respect to slight variations in the geometrical inputs (PZT to PZT distance and thickness of the plate) are validated within ± 1% and ± 2%, respectively, with the FEM. Experimental results are validated within ± 1% of supplier properties, demonstrating the ability of this approach to allow accurate characterization of a structure in situ without the need for complex and expensive devices or ASTM testing.

A data-driven method for predicting structural degradation using a piezoceramic array

“…Guided wave PZT based SHM systems are being explored in current research and show promise in damage detection, localization, and material characterization for aerospace structures and are ideal candidates for in-situ data generation and gathering (Giurgiutiu & Bao, 2004;Quaegebeur, Masson, Langlois-Demers, & Micheau, 2010;Saxena et al, 2011;Ostiguy, Quaegebeur, Mulligan, Masson, & Elkoun, 2012). Before implementing such a system for structural assessment, key considerations must be made for transducer signal generation and acquisition parameters.…”

“…Some of these features may be sensitive to different frequency ranges which vary by material. Therefore, in this study, considerations made for parameter selection are based on damage analysis and material characterization techniques (Giurgiutiu & Bao, 2004;Quaegebeur et al, 2010;Ostiguy et al, 2012).…”

In-Situ Characterization of Isotropic and Transversely Isotropic Elastic Properties Using Ultrasonic Wave Velocities

“…To overcome this problem, non-destructive methods such as ultrasonic waves using time of flight analysis and Lamb waves have been used to find the elastic properties of the material. Typically these properties consist of: Poisson's ratio, tensile and shear stiffness in different directions for isotropic and anisotropic medium [1]. This paper focuses on the use of ultrasonic waves' time of flight for material property determination.…”

Non-destructive evaluation of coating thickness using guided waves

“…The dispersive behavior of guided waves at some frequencies [17] can be used for thickness measurement. Structural thickness can be estimated based on Time-of-Flight (ToF) via point-by-point measurements in a pitch-and-catch configuration [15,18,19,20,21], 2D FFT [14], by addressing frequency shift variations in guided waves [13], or even by considering the dispersive behavior of guided waves using analytical formulations [22].…”