TY - JOUR
T1 - Imaging of Defect Signal of Reinforcing Steel Bar at High Lift-Off Using a Magnetic Sensor Array by Unsaturated AC Magnetic Flux Leakage Testing
AU - Hayashi, Minoru
AU - Kawakami, Taisei
AU - Saito, Taisuke
AU - Sakai, Kenji
AU - Kiwa, Toshihiko
AU - Tsukada, Keiji
N1 - Publisher Copyright:
© 1965-2012 IEEE.
PY - 2021/2
Y1 - 2021/2
N2 - Reinforcing steel bars (rebars) in the concrete need to be inspected to prevent the structure from collapsing. Magnetic nondestructive testing methods can inspect the rebar without the influence of concrete. However, since the inspection is performed at a high lift-off on concrete, a strong applied magnetic field is required in order to measure a sufficient magnetic signal generated from the rebar. In addition, if a single sensor is used to measure the rebar, this requires the scanning of extensive area along the invisible rebar covered with the concrete. To overcome these problems, we have developed a method to detect and image the defect signal using unsaturated ac magnetic flux leakage (USAC-MFL) testing combining a magnetic sensor array probe. The USAC-MFL is a method that uses an alternating magnetic field in the initial magnetization characteristics of steel, which does not require a strong applied magnetic field compared to the conventional MFL method. By measuring the magnetic flux from the rebar in a wide area using the magnetic sensor array probe, the defect signal was able to be detected and imaged. The defect signal was able to be confirmed up to the lift-off of 100 mm even when the defect was half length of the rebar or located on the back side.
AB - Reinforcing steel bars (rebars) in the concrete need to be inspected to prevent the structure from collapsing. Magnetic nondestructive testing methods can inspect the rebar without the influence of concrete. However, since the inspection is performed at a high lift-off on concrete, a strong applied magnetic field is required in order to measure a sufficient magnetic signal generated from the rebar. In addition, if a single sensor is used to measure the rebar, this requires the scanning of extensive area along the invisible rebar covered with the concrete. To overcome these problems, we have developed a method to detect and image the defect signal using unsaturated ac magnetic flux leakage (USAC-MFL) testing combining a magnetic sensor array probe. The USAC-MFL is a method that uses an alternating magnetic field in the initial magnetization characteristics of steel, which does not require a strong applied magnetic field compared to the conventional MFL method. By measuring the magnetic flux from the rebar in a wide area using the magnetic sensor array probe, the defect signal was able to be detected and imaged. The defect signal was able to be confirmed up to the lift-off of 100 mm even when the defect was half length of the rebar or located on the back side.
KW - High lift-off
KW - magnetic flux leakage (MFL) testing
KW - magnetic sensor array
KW - reinforcing steel bar (rebar)
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U2 - 10.1109/TMAG.2020.3017722
DO - 10.1109/TMAG.2020.3017722
M3 - Article
AN - SCOPUS:85099886403
VL - 57
JO - IEEE Transactions on Magnetics
JF - IEEE Transactions on Magnetics
SN - 0018-9464
IS - 2
M1 - 9171309
ER -