Nondestructive Evaluation of Thin Thickness Metal Plate by using the Sheet-Type Induced Current and Linearly Integrated Hall sensor Array

Abstract

ABSTRACT

Nondestructive Testing Nondestructive Evaluation of Thin Thickness Metal Plate by using the Sheet-type Induced Current and Linearly Integrated Hall Sensor Arrays

Vu Hoang Hai Advisor: Prof. Jinyi Lee, PhD Dept. of Control and Instrumentation Eng., Graduate School of Chosun University.

This thesis introduces an AC-type magnetic camera in quantitative evaluation of crack in eddy current testing. The AC-type magnetic camera consists of a sheet-type induced current (STIC) source, a linearly integrated Hall sensor array (LIHaS), a linear guided scanner, amplifiers, root-mean-square (RMS) converter, analog-to-digital converter and a computer. Plate specimens made of different material such as titanium, copper-nickel, inconel600, stainless steel (STS304) was used. Cracks with different sizes and depths were introduced in the specimens to simulate the corrosion in the metal structures. When the STIC is excited with an alternating current and bring proximity to the test material, consequently eddy current will be induced in the test material. The presence of corrosion or crack distorts the eddy current and this distortion could be measured by linearly integrated Hall sensor arrays. During the experiment, the LIHaS is placed on the specimens and scanning was performed using linear guide scanner to inspect the cracks on the surface of the specimen (near/far-side crack). Different excited frequencies were used to study the effect of detectability of the defects in the test specimens. Subsequent to successful detection of all the kinds of cracks, several quantitative algorithms were developed to discriminate the location of crack (near/far-side) and estimate the crack volume in the thin-thickness metal plate. KEYWORDS: NDT, Crack, Eddy current testing, Discrimination, Eddy Current.