Quantitative estimating size of deep defects in multi-layered structures from eddy current NDT signals using improved ant colony algorithm

Bo Ye,Jun Dong,Gefei Qiu,Fang Zeng,Ming Li

doi:10.3221/igf-esis.28.04

Abstract

Detection and quantitative estimation of deep defects in multi-layered structures is an essential task in a range of technological applications, such as maintaining the integrity of structures, enhancing the safety of aging aircraft, and assuring the quality of products. A novel approach to accurately quantify the two-dimensional axisymmetric deep defect size from eddy current nondestructive testing (NDT) signals is presented here. The method uses a finite element forward model to simulate the underlying physical process and an improved ant colony algorithm (IACA) to solve the inverse problem. Experiments are carried out. The performance comparison between the IACA method and the least square method is shown. The comparison results demonstrate the feasibility and validity of the IACA method. Between them, the IACA method gives a better estimation performance than the least square method at present.

Highlights

Multi-layered structures are widely used in many different structural systems, such as nuclear structures, composite aircraft structures, and other civil engineering structures [1]
To check the multi-layered structures, various nondestructive testing (NDT) techniques are used, such as visual inspection, eddy current (EC) technique, ultrasonic technique, X-rays, etc. Among these NDT techniques, the eddy current nondestructive testing (ECNDT) method is a useful technique for detecting defects in conductive materials, especially in multi-layered structures
We propose a method of inversing eddy current NDT signals to quantify deep defect size using an iterative improved ant colony algorithm (IACA)

Summary

INTRODUCTION

Multi-layered structures are widely used in many different structural systems, such as nuclear structures, composite aircraft structures, and other civil engineering structures [1]. To check the multi-layered structures, various nondestructive testing (NDT) techniques are used, such as visual inspection, eddy current (EC) technique, ultrasonic technique, X-rays, etc. To simplify the eddy current scanning detective problem into a two-dimension axisymmetric problem, and using cylindrical coordinates O (ρ, θ, z) shown, the Laplace expression 2A of the vector function A is Figure 2: The cylindrical coordinates and triangle unit subdivision To simplify the eddy current scanning detective problem into a two-dimension axisymmetric problem, and using cylindrical coordinates O (ρ, θ, z) shown in Fig. 2, the Laplace expression 2A of the vector function A is Figure 2: The cylindrical coordinates and triangle unit subdivision

A z 2

X t r t r

CONCLUSION