Stress Measurement Apparatus Based on PulsedMagnetic Field

An apparatus was designed for measuring the internal stress in steel. Extrinsic hysteresis loops, magnetization curves, and surface field loops were measured at a pulsed magnetic field of 5 kA/m. It was found that the magnetic parameters change monotonically with compressive stress. The technical index shows that maximum magnetic flux density is an excellent evaluation parameter, reflecting stress with a precision of 1.6% and standard deviation of 3.185 x 10(-4) T. In addition, the detection depth can reach 5 mm by employing this technique.