Detecting Delamination via Nonlinear Wave Scattering in a Bonded Elastic Bar

TL;DR

This paper investigates how delamination affects nonlinear wave scattering in layered elastic bars, proposing a method to predict delamination length based on wave structure changes, which aids in structural integrity testing.

Contribution

It introduces a novel framework linking wave structure changes to delamination length, using coupled Boussinesq-type equations and inverse scattering transform analysis.

Findings

Wave structure changes depend on FWHM of incident soliton in perfect bonding.

Numerical predictions match theoretical models for delamination length.

A unified approach for different bonding types to assess delamination.

Abstract

In this paper we examine the effect of delamination on wave scattering, with the aim of creating a control measure for layered waveguides of various bonding types. Previous works have considered specific widths of solitary waves for the simulations, without analysing the effect of changing the soliton parameters. We consider two multi-layered structures: one containing delamination "sandwiched" by perfect bonding and one containing delamination but "sandwiched" by soft bonding. These structures are modelled by coupled Boussinesq-type equations. Matched asymptotic multiple-scale expansions lead to coupled Ostrovsky equations in soft bonded regions and Korteweg-De Vries equations in the perfectly bonded and delaminated region. We use the Inverse Scattering Transform to predict the behaviour in the delaminated regions. In both cases, numerical analysis shows that we can predict the delamination length by changes in the wave structure, and that these changes depend upon the Full Width at Half Magnitude (FWHM) of the incident soliton. In the case of perfect bonding, we derive a theoretical prediction for the change and confirm this numerically. For the soft bonding case, we numerically identify a similar relationship using the change in amplitude. Therefore we only need to compute one curve to determine the behaviour for any incident solitary wave, creating a framework for designing measurement campaigns for rigorously testing the integrity of layered structures.