Listening for Airborne Sound of Damage: A New Mode of Diagnostic Imaging

Dmitry Solodov,Dieter Müller,Marc Kreutzbruck,Yannick Bernhardt

doi:10.3389/fbuil.2020.00066

Abstract

Resonant air-coupled emission (RACE) is a new method of detecting damage based on local damage resonance (LDR). Resonant vibrations in defect excite airborne acoustic wave, which emanates from the damaged area, and therefore could be used for diagnostic imaging. A conventional approach to RACE imaging uses C-scanning of flat surfaces with a microphone and provides high resolution imaging in the near field zone. In this paper, some features of RACE field are studied experimentally to recognize the possibility of imaging in transition zone between the near- and far-fields. A modification of the RACE scanning mode by using a robot is investigated to be applied to complex shape components. An alternative imaging technique proposed uses a microphone array and provides full-field visualization of RACE field. The 64 microphone acoustic camera array is applied for express testing and imaging. Multiple case studies are given to demonstrate the potential of the both modes for diagnostic imaging of simulated and realistic defects in polymers and composite materials.

Highlights

Lightweight, fiber-reinforced composite materials have been a continually growing industry in recent years
In the higher kHz frequency range, the Resonant air-coupled emission (RACE) field can be readily detected in the transition zone between near- and far- fields that extends well beyond mm-range
Study of the RACE features implemented in the paper confirms that the RACE field is produced by the resonant vibrations of a defect (LDR)

Summary

INTRODUCTION

Lightweight, fiber-reinforced composite materials have been a continually growing industry in recent years. This paper proposes a new version of AE that differs from its traditional counterparts It is based on detecting specific airborne sound of damage [resonant air-coupled Emission (RACE)] (Solodov et al, 2017) activated by its resonant vibrations due to local defect resonance (LDR). The LDR approach has generated much interest in development and applications of efficient resonant techniques for NDT and imaging of defects in composites (Fierro et al, 2017; Hettler et al, 2017; Rahammer and Kreutzbruck, 2017; Pieczonka et al, 2018; Segers et al, 2018; Roy et al, 2019). To demonstrate the potential of the both modes for diagnostic imaging of simulated and realistic defects

EXPERIMENTAL PROCEDURE RACE Field Features

CONCLUSIONS