Papers by Author: Masato Enokizono

Abstract: Magnetizations and optical Faraday effects have been intensitvely studied in transparent glasses of almost all Lanthanide elements with 20mol % in pulsed magnetic fields up to 30T in the temperature range between 1.8K-RT. The internal effective fields were investigated by observing Verdet constants as a function of applied fields and as a function of magnetizations in the wavelength range between 400nm and 2600nm, intensively for Nd, Pr , Tb and Dy glasses respectively. We obtained a magnet of Dy (30mol%) glass with optically transparent and adhesive to conventional magnet at the room temperature. The magnetizations of these glasses showed paramagnetism at the room temerature and showed super-paramagnetim at cryogenic temperatures below 4.2K.

Abstract: M-Heff full curves up to 19T for the permanent magnets composed of Nd-Fe-B were very precisely observed by using specially designed magnetizer. The pulsed magnetic field directions were safely reversed with the same coil-end to ground side of coil positive and negative field directions. The coercivity enhancements were observed by 15% in high pulsed field applications.

Abstract: This paper presents distributions of the local vector magnetic properties in a three-phase induction motor model core measured with a new vector hysteresis sensor (V-H sensor). The exciting conditions used in the measurements were common sinusoidal and PWM excitation. The influence of the modulation frequency on vector magnetic properties is made clear.

Abstract: The purpose of this paper is to present the results of observation of material degradation process in steel samples under combined conditions of static and cyclic dynamic loading, using selected electromagnetic NDT methods. To evaluate damages a Barkhausen noise observation, an AC magnetization, a magnetic flux leakage and eddy current method were used.

Abstract: MR (Magnetic Rheological) fluid is a kind of functional fluid, which can be hardened by impressing magnetic flux. MR fluid has the high speed response to the external magnetic field and a big yield stress in comparison with the ferrofluid. In recent years, various devices utilizing MR fluid have been developed. Such developments are enabled with knowledge based on measured viscoelastic properties of MR fluid. However, precise measurement to obtain effect of the magnetic field on viscoelasticity is very difficult. The difficulty exists in generating a uniform magnetic field and evaluating the effective magnetic field. Accurate measurements become possible by solving these problems. In this paper, we propose a new magneto-viscoelasticity measurement system of MR fluid, which can generate a uniform magnetic field.

Abstract: In this paper, the iron loss of an actual stator core of the complex configuration was evaluated by using the proposed effective magnetic path length and the excitation inner core, which were developed in this research. The iron loss of an actual stator core in the manufacturing process was described. Iron losses of actual stator cores before and after the varnish processing were measured using the excitation inner core of several kinds of shapes. As a result, iron losses of actual stator cores evaluated using the proposed effective magnetic path length were within appropriate values.

Abstract: New flux concentrated hybrid (HB) type radial and axial magnetic bearings are proposed in this paper. It is intended to use ferrite permanent magnet (PM) for producing high bias flux. The capability of proposed magnetic bearings is confirmed using commercial FEM code “ANSYS”. The results show high possibility with less expensive PMs.

Abstract: This paper presents comparison of feedback control algorisms of magnetic flux conditions in two-dimensional vector magnetic property measurements under high magnetic field over 1.6 T. In order to develop a fast measurement algorism, several PID feedback control methods were tested. The results show that the proportion-derivative precedence type (I-PD) control is suitable for reduction of measurement times in vector magnetic property measurements.

Abstract: An NDE measurement for internal defects of metal casting products is presented. An experimental system for ECT is developed in order to inspect internal defects of brass casting which have complicated and inaccurate shapes. In the measurement, artificial defect specimen made for fundamental experiments and brass casting specimens are evaluated by multi-frequency excitation and spectrogram (MFES) method. From the results, validity of our measurement system is discussed.

Abstract: This paper presents measured magnetic and shape memory properties of Fe-Mn-Cr-Si-Sm-B ferromagnetic shape memory ribbons depending on tensile stress and temperature. The samples were produced with the melt spinning method in air and the magnetic properties were measured with an open solenoid type measurement system under controlling their temperature and tensile load. The alloys are multi-functional materials, which have both the ferromagnetic property and shape memory property. The measured results show applicability of the produced ribbon in applications for magnetic sensors and actuators.