Development of Magnetic Hammering Test Using Tunnel Magneto-Resistive Sensor

Abstract

We have developed a novel nondestructive inspection technique for infrastructures using spintronics technologies. Since the tunnel magneto-resistance (TMR) effect has become dramatically more sensitive in recent years, TMR sensors can be applied to the highly sensitive nondestructive inspection named magnetic hammering test (MHT). The proposed MHT technique is based on the principle of detecting slight fluctuations in the spatial magnetic field caused by the vibration of steel materials. Since the fluctuations in the magnetic field occur with the natural vibration frequency of the steel materials, their condition can be detected from the change of natural frequency using highly sensitive TMR sensors. In this work, we have demonstrated that the size of steel plates was determined with high accuracy using the MHT technique.