50th Anniversary Article: Comparison Studies of Full Wavefield Signal Processing for Crack Detection

Abstract

ABSTRACTThe signals acquired by measurements of elastic wave propagation have been used for damage detection since the 1970s. The measurements have been carried out mostly by using piezoelectric transducers of various types. Many different sensor configurations and data processing have been proposed to detect and localise structural defects, both for real‐time and off‐line testing.Nevertheless, in the last decade, significant progress in the measurement techniques such as scanning laser Doppler vibrometry and shearographic interferometry has been made. These techniques enable measurement of a full wavefield of elastic waves. This opens up new possibilities and solutions for the problems of the damage detection in structures. Many researchers successfully applied this type of measurements for the damage detection and localisation in thin‐walled structures. Moreover, advanced signal processing techniques, such as wavenumber filtering, give the possibility of damage size estimation, by filling the gap between damage detection and damage prognosis.The aim of this paper is to give a comprehensive review of methods used for the full wavefield measurement. It also describes and compares selected signal processing algorithms developed for damage detection and visualisation based on these measuring techniques. Criticism aspects, as well as advantages of each algorithm, are denoted based on the authors' expertise in the field.