Damage Size Quantification Using Lamb Waves by Analytical Model Identification

Abstract

Thanks to their mechanical properties, composite materials are widely used in the aeronautic industry. However, they are subject to internal damages like delamination that can threaten structural integrity while being invisible to the naked eye. Structural Health Monitoring (SHM) allows to ensure in real-time that aircraft substructures can still perform their function. Among all the technologies used in SHM, the emission/reception of Lamb waves makes it possible to obtain a lot of information regarding the state of the structure since one knows the input signal in addition to the output signal. Algorithms using Lamb waves for damage detection and localization already exist in the literature but damage size estimation is still an open problem. In this paper, we propose a baseline-free approach to quantify delamination damage size by relying on an analytical scattering model. The structure considered is a plate equipped with piezoelectric transducers (PZT) acting both as actuators and sensors. We use the framework of the Mindlin-Kane plate theory to describe S0-mode Lamb wave propagation. We make the assumption that the S0 mode can be assimilated to an extensional-compressional wave. The damage considered is a cylindrical inhomogeneity where the mechanical properties are different from the rest of the plate. The analytical model derived takes into account the signal emission by a PZT, the scattering by the damage, and the reception by a sensor PZT. This model is then used in an identification process to estimate the size of the damage by minimizing a dedicated cost function. The proposed approach is applied on simulation data using aluminum plate.

An enhanced topological analysis for Lamb waves based SHM methods

“…In the context of Structural Health Monitoring (SHM), detecting damages and impacts is very important to estimate the remaining useful life 1 and to develop a predictive maintenance process. 2 There are classically five main steps in a SHM process:…”

“…Methods relying on such damage indexes have already proved to be able to monitor damages inside a composite structure. 2,5,9 The topological data analysis (TDA) is an alternative method that allows to extract topological features from a given dataset. It can be interpreted as an original manner to quantify the 'shape' of multidimensional data and provides a new way to infer damage indexes for high dimensional data spaces.…”

“…In the context of Structural Health Monitoring (SHM), detecting damages and impacts is very important to estimate the remaining useful life 1 and to develop a predictive maintenance process. 2 There are classically five main steps in a SHM process: (1) damage detection, (2) damage localization, (3) damage classification by type, (4) damage severity for the structure and (5) prognostic of the structure health. As detailed in the paper 3 written by Rahbari et al the SHM research community agreed on solving these issues through four different steps.…”

“…These approaches are well covered by the literature. 1,2,5 Many methods have been validated to assess several steps for SHM purposes. Wavelet analysis with Lamb wave measurement can be efficient for quantification.…”

“…Methods relying on such damage indexes have already proved to be able to monitor damages inside a composite structure. 2,5,9…”