# Surface Crack Detection of Aluminum Alloy Using Injected Direct Current-Magnetic Field Measurement Method

## TL;DR

This paper introduces a new nondestructive method using magnetic field measurements to detect cracks in aluminum alloys, showing it is highly sensitive and effective.

## Contribution

The study demonstrates the feasibility of IDC-MFM for quantitative crack evaluation in aluminum alloys through simulation and experimental validation.

## Key findings

- The magnetic field at defects increases with current, and ΔBxpp correlates well with crack width and depth.
- ΔBxpp shows a nonlinear positive correlation with crack width and a linear positive correlation with crack depth.
- IDC-MFM is shown to be a feasible and sensitive method for crack size detection in aluminum alloys.

## Abstract

Injected Direct Current-Magnetic Field Measurement (IDC-MFM) is a promising nondestructive technique for crack evaluation of aluminum alloy due to its high sensitivity to defect states. Finite element simulation and experiment were introduced in this research to reveal the relationship between the magnetic field and the crack size. The finite element simulation showed that the magnetic field at the defect increased with the currents, and the peak-to-peak value of the tangential component magnetic field Bx (ΔBxpp) correlated with both the width and depth of the crack very well. The high-sensitivity tunnel magnetoresistance probe was used for crack detection of aluminum alloy specimens with different crack widths and depths, and the results show that the relationship between the ΔBxpp and the crack was consistent with the simulation results, and ΔBxpp has a nonlinear positive correlation with crack width and a linear positive correlation with crack depth. The results of the present work show that IDC-MFM has high sensitivity in crack size detection and is a feasible solution for the quantitative evaluation of cracks in aluminum alloy.