The Evaluation of Fatigue Caused by Plane-Bending Stress on Stainless Steel Using the Stacked-Coil Type Magnetic Sensor

To prevent an accident due to the metal degradation of stainless steels, we have previously proposed fatigue evaluation methods (such as the remnant magnetization method using a thin-film flux-gate magnetic sensor [1] and the inductance method using a pan-cake type coil [2]). These two fatigue evaluation methods demonstrated a good correlation between the magnetic sensor output signal and the amount of plane-bending fatigue damage in stainless steels. We developed a stacked-coil type magnetic sensor shown in Fig. 1(a) in order to achieve a magnetic sensor for an accurate fatigue evaluation. This magnetic sensor was composed of two detection coils that are connected differentially, an excitation coil, and a ferrite core. Fig. 1(b) shows the connection of the excitation coil and the two detection coils. Fig. 2 shows the detection result of fatigue and crack using this magnetic sensor. The material used for this specimen was an austenitic stainless steel (SUS304), and plane-bending stress was applied. From Fig. 2, it can be seen that this magnetic sensor detected defects well. The evaluation results of plane-bending fatigue damage distribution will be shown in in detail the complete paper

The Evaluation of Fatigue Caused by Plane-Bending Stress on Stainless Steel Using the Stacked-Coil Type Magnetic Sensor

To prevent an accident due to the metal degradation of stainless steels, we have previously proposed fatigue evaluation methods (such as the remnant magnetization method using a thin-film flux-gate magnetic sensor [1] and the inductance method using a pan-cake type coil [2]). These two fatigue evaluation methods demonstrated a good correlation between the magnetic sensor output signal and the amount of plane-bending fatigue damage in stainless steels. We developed a stacked-coil type magnetic sensor shown in Fig. 1(a) in order to achieve a magnetic sensor for an accurate fatigue evaluation. This magnetic sensor was composed of two detection coils that are connected differentially, an excitation coil, and a ferrite core. Fig. 1(b) shows the connection of the excitation coil and the two detection coils. Fig. 2 shows the detection result of fatigue and crack using this magnetic sensor. The material used for this specimen was an austenitic stainless steel (SUS304), and plane-bending stress was applied. From Fig. 2, it can be seen that this magnetic sensor detected defects well. The evaluation results of plane-bending fatigue damage distribution will be shown in in detail the complete paper.</p

Magnetic characterization of the stator core of a high-speed motor made of an ultrathin electrical steel sheet using the magnetic property evaluation system

Recently, the application areas for electric motors have been expanding. For instance, electric motors are used in new technologies such as rovers, drones, cars, and robots. The motor used in such machinery should be small, high-powered, highly-efficient, and high-speed. In such motors, loss at high-speed rotation must be especially minimal. Eddy-current loss in the stator core is known to increase greatly during loss at high-speed rotation of the motor. To produce an efficient high-speed motor, we are developing a stator core for a motor using an ultrathin electrical steel sheet with only a small amount of eddy-current loss. Furthermore, the magnetic property evaluation for efficient, high-speed motor stator cores that use conventional commercial frequency is insufficient. Thus, we made a new high-speed magnetic property evaluation system to evaluate the magnetic properties of the efficient high-speed motor stator core. This system was composed of high-speed A/D converters, D/A converters, and a high-speed power amplifier. In experiments, the ultrathin electrical steel sheet dramatically suppressed iron loss and, in particular, eddy-current loss. In addition, a new high-speed magnetic property evaluation system accurately evaluated the magnetic properties of the efficient high-speed motor stator core