According to the principle of magnetic leakage signal
superposition, the theory should be consistent with the con-
clusion of the previous studies however, to improve the
accuracy of the conclusions, experimental simulation is carried
out again. Assuming that the thickness of the sample remains
unchanged at 5 mm, a rectangular discontinuity with a width
of 4 mm and a depth of 2 mm is set up on one side of the
sample, and a V-shaped discontinuity with a width of 4 mm
and a depth of 2 mm is set up on the other side. The edge
angles are set to 34°, 45°, and 63°, as shown in Figure 6a.
Figure 6c shows considerable fluctuations in the peaks on
both the left and right sides of the radial signal map. The radial
signal peaks increase with the edge angle and gradually move
away from the center position of the discontinuity. In Figure 6d,
the position of the axial signal peak gradually shifts to the left as
the edge angle increases, while the peak intensity also increases.
This is consistent with the trend plot in Figure 6b.
This finding supports the previous observation, demon-
strating that as the edge angle of the discontinuity increases, the
magnetic field lines on the discontinuity side become more con-
centrated. This concentration effect produces a strong magnetic
field gradient on one side of the discontinuity, which results in
the formation of distinct wave peaks in the detection signal.
Experimental Validation and Analysis
To verify the correctness of the simulation conclusions, we
built a simple magnetic leakage detection platform for the
experiment. The main equipment of the platform includes an
excitation coil, mobile platform, a Hall sensor, a microcontrol-
ler, a 5A AC/DC power supply, an experimental steel plate, and
a computer. The specific physical setup is shown in Figure 7.
During the experiment, the magnetic yoke and sensor are
driven horizontally by the moving platform at a constant speed
to collect point-to-point signals for the discontinuities on the
steel plate and present the data in the form of 2D curves on
the computer. This is consistent with the principle of COMSOL
simulation.
Experimental Analysis of Different V-shaped
Discontinuities
Discontinuities with depths of 0.73 mm, 2 mm, and 4.3 mm
were processed on a steel plate with a thickness of 5 mm.
V-shaped discontinuities with edge angles of 20°, 45°, and 65°
were created while keeping the discontinuity width constant
at 4 mm. The detection signals were obtained using Hall
sensors, as shown in Figures 8a and 8b. The X-axis represents
the number of scanning points along the discontinuities, while
the Y-axis represents the magnetic induction strength (B)
0 10
0
20
40
60
80
100
120
140
160
180
20 30
Scanning point
100
50
0
–50
–100
–150
150
40 50 60 70
0 10 20 30
Scanning point
40 50 60 70
65°
45°
20°
65°
45°
20°
Figure 8. Magnetic leakage signal detection of V-shaped discontinuities
with different edge angles: (a) radial signal component (b) axial signal
component.
Figure 7. Experimental test platform: (a) excitation coil (b) mobile
platform (c) Hall sensor (d) microcontroller (e) steel plate.
M AY 2 0 2 5 • M AT E R I A L S E V A L U AT I O N 37
B
(mT)
B
(mT)

corresponding to each scanning point. The magnetic induction
strength variation along the entire discontinuity is obtained by
connecting the B values of each scan point. The same princi-
ple applies to subsequent trapezoidal discontinuity and inner/
outer discontinuity detection.
Figures 8a and 8b show that the signal peak gradually
increases with the edge angle. Additionally, relative to the
center position of the discontinuity, increasing the edge angle
leads to a greater distance between the peak point and the
center position. The experimental results are largely consistent
with the simulation analysis.
Experimental Analysis of Different Trapezoidal
Discontinuities
Under the premise that the thickness of the steel plate remains
unchanged at 5 mm, right-angled trapezoidal discontinu-
ities with a depth of 2 mm, a width of 4 mm, and a unilateral
edge angle of 39°, 45°, 53°, 63°, 76°, and 90°, respectively, are
processed. The detection signals obtained from their Hall
sensors are shown in Figures 9a and 9b.
From Figures 9a and 9b, it can be seen that under the same
width and depth, as the edge angle increases, the peak of the
radial signal increases, and the distance from the peak point to
the center of the discontinuity widens more rapidly. Although
the axial signal results are slightly different from the simulation,
they all exhibit a single wave peak, and the peak shifts with
changes in the edge angle. Therefore, the experimental results
are generally consistent with the simulation analysis.
Experimental Analysis of Inner and Outer
Discontinuities
A rectangular discontinuity is machined on the inner surface
of the plate, and a V-shaped discontinuity with different edge
angles is machined on the outer surface. The centers of the two
discontinuities are exactly aligned. The thickness of the steel
plate is maintained at 5 mm, and the width of the discontinuity
ME
|
MAGNETICLEAKAGE
0 10
0
20
40
60
80
100
120
20 30
Scanning point
20
40
60
80
0
–20
–40
–60
–80
40 50 60 70 0 10 20 30
Scanning point
40 50 60 70
90°
76°
63°
53°
45°
39°
90°
76°
63°
53°
45°
39°
Figure 9. Magnetic leakage signal detection of trapezoidal discontinuities with different edge angles: (a) radial signal component (b) axial signal
component.
0 10
0
20
40
60
80
100
120
140
160
20 30
Scanning point
20
40
60
80
0
–20
–40
–60
–80
40 50 60 70 0 10 20 30
Scanning point
40 50 60 70
63°
45°
34°
63°
45°
34°
Figure 10. Magnetic leakage signal detection of inner and outer discontinuities with different edge angles: (a) radial signal component (b) axial
signal component.
38
M AT E R I A L S E V A L U AT I O N • M AY 2 0 2 5
B
(mT)
B
(mT)
B
(mT)
B
(mT)