Lamb waves in thermoplastic polymer plates: An application to monitoring

Abstract

Thin thermoplastic polymer components are widely used in different fields of engineering, including high-technology industries such as automotive or energy. Due to the rapid technological development in these industries, there is an increased demand for polymer components to achieve advanced functionalities, such as the continuous monitoring of their structural health. In this work, we propose to take advantage of elastic guided waves, which are both emitted and measured using arrays of transducers integrated within the structure. This application requires first investigating the Lamb waves in these attenuating and heterogeneous materials. To that end, we estimate the dispersion curves of Lamb waves using a laser vibrometer. A transversely isotropic material model and a fitting algorithm allow for estimating the elastic parameters of the specimens. Then, for each mode, the frequency-dependent attenuation is evaluated. Finally using both theoretical models and experimental analysis, we evaluate the sensitivity of the guided waves to asses various structural changes in the thermoplastic polymer components such as temperature or the presence of contaminants.