A low-cost flexible instrument made of off-the-shelf components for pulsed eddy current testing: overview and application to pseudo-noise excitation

TL;DR

This paper presents a low-cost, flexible eddy current testing device using off-the-shelf components, capable of generating various waveforms and detecting small cracks effectively, with potential for further portability and performance improvements.

Contribution

It introduces a novel, affordable eddy current testing system with pseudo-noise excitation, demonstrating effective crack detection and ease of integration with single-board computers.

Findings

Successfully detected all artificial cracks on a benchmark sample.

Demonstrated flexible waveform generation including pseudo-noise signals.

Validated the system's effectiveness with different commercial data acquisition devices.

Abstract

A flexible and low-cost device for eddy current non-destructive testing made of off-the-shelf components is described. The proposed system is compact and easy to operate, and it consists of a dual H-bridge stepper motor driver, a coil winded in-house on an additively manufactured support, a tunnel magnetoresistance sensor, and a data generation/acquisition module. For the latter, two different commercial devices have been used, and both setups have been then tested on a benchmark sample to detect small artificial cracks. The system can flexibly generate the square pulse or square wave with tunable duration and frequency, as well as pseudo-noise binary waveforms that are here used in combination with pulse-compression to increase the inspection sensitivity with respect to standard pulsed eddy current testing. A benchmark sample was analysed, and all the defects were correctly located, demonstrating the good detection capability of the sensor. This was achieved by assembling a very low-cost handy device, which can be further improved in portability and performances with the use of different off-the-shelf components, and that can be easily integrated with single-board PC, paving the way for future developments in this field.