International Journal of Applied Electromagnetics and Mechanics - Volume 59, issue 1

Authors: Itahashi, Yuta | Hirano, Ryutaro | Sawada, Tatsuo

Article Type: Research Article

Abstract: This study reports magnetic-fluid flow in a square duct under DC, AC, and DC+AC magnetic fields. We measure the pressure drop under application of different magnetic fields to the flow. Under all magnetic fields, flow resistance increased by forming a cluster, causing the pressure drop and friction factor to also increase. From an FFT analysis of the pressure drop, we obtained different power spectra for AC and DC+AC magnetic fields.

Keywords: Magnetic fluid, oscillating magnetic fields, pressure drop, square duct

DOI: 10.3233/JAE-171105

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 1, pp. 335-340, 2019

Authors: Fukumoto, Takashi | Tanaka, Yuya | Sawada, Tatsuo

Article Type: Research Article

Abstract: This paper reports the experimental studies on a magneto-rheological (MR) fluid under AC magnetic fields. Magnetic clusters in the MR fluid are formed along the magnetic fields. The ultrasonic propagation velocity changes owing to the presence of clustering structures in the MR fluid. We investigated clustering structures by measuring this change in the ultrasonic propagation velocity. The results indicate that magnetic clusters in the MR fluid depend on the elapsed time, intensity, frequency, and angle of the AC magnetic fields.

Keywords: Magnetic fluid, ultrasonic wave, AC magnetic field, anisotropy

DOI: 10.3233/JAE-171174

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 1, pp. 341-347, 2019

Authors: Tian, Tongfei | Nakano, Masami

Article Type: Research Article

Abstract: Isotropic and anisotropic silicone rubber-based magnetorheological (MR) elastomers with various concentrations of silicone oil were fabricated, and their dynamic viscoelastic properties were measured. The tested results showed that the silicone oil played an important role in the MR elastomers. The sample with a higher concentration of silicone oil had lower zero-field storage modulus and larger storage modulus increasing rate. For the MR elastomer without silicone oil, the anisotropic sample showed higher storage modulus increasing rate than its isotropic counterpart. However, for the MR elastomers with 15% weight fraction of silicone oil, the isotropic sample dominated in the storage modulus increasing …rate. Show more

Keywords: Magnetorheological (MR) elastomer, silicone rubber, silicone oil, dynamic viscoelasticity, storage modulus

DOI: 10.3233/JAE-171162

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 1, pp. 349-355, 2019

Authors: Dong, Longlei | Zhao, Ruigang | Luo, Baomin | Han, Yi

Article Type: Research Article

Abstract: To optimise the working performance of magnetorheological damper, a new parallel gap magnetorheological damper is designed. The validity of the structural design is verified and guided by establishing a mathematical model of a parallel gap magnetorheological damper. The damper is designed using a check valve structure, which greatly reduces the installation space, reduces the transfer linkage, and improves the reliability of the damper. The newly-designed damper has many advantages, such as high efficiency, high sensitivity, no precipitation, good heat dissipation, greater damping force, and so on. The experimental and theoretical analysis results show that the performance of the parallel gap …magnetorheological damper is excellent. Show more

Keywords: Parallel gap, magnetorheological fluids, damper, one-piece structure

DOI: 10.3233/JAE-171132

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 1, pp. 357-366, 2019

Authors: Han, Yi | Dong, Longlei | Hao, Caifeng

Article Type: Research Article

Abstract: Considering the particular demands for a large damping force in special vehicles, a new design for a parallel disc slotted magnetorheological damper is presented. In this damping generator, the direction of liquid flow between disc gaps is completely perpendicular to the magnetic flux direction, and the gaps can be cascaded to enhance the damping effect, thereby introducing a larger damping force based on the magnetorheological effect. In this paper, the damping characteristics of the new damper design are experimentally analysed first. Based on the experimental results, a dynamic model for the damper is constructed. The mathematical model is obtained by …combining the Bingham model and the Herschel-Bulkley model, and accurately and clearly describes the characteristics of magnetorheological fluid. For parameter identification, two methods are utilized: a trial-and-error method and a recursive least squares method. Analysis shows that both methods have drawbacks. Lastly, a new method is proposed for combining the trial-and-error method with recursive least squares method. By comparing the theoretical curves obtained from the experimental curves and combined methodology, the results show that the combined methodology exhibits the highest accuracy as well as efficiency. The mathematical model established in this paper can accurately describe the characteristics of damping force. This model lays down the theoretical foundations for application and research on new parallel disk slotted magnetorheological dampers. Show more

Keywords: Magnetorheological damper, damping characteristics, mathematical model, parameters identification

DOI: 10.3233/JAE-171146

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 1, pp. 367-376, 2019

Authors: Liedtke, Lukas | Gueltig, Marcel | Kohl, Manfred

Article Type: Research Article

Abstract: A miniature-scale device for harvesting of vibrational energy is presented, which is based on the inverse magnetic shape memory effect caused by stress-induced reorientation of magnetic moments. The active material is a bulk NiMnGa sample of 1 mm × 2.5 mm × 4.5 mm. A new harvester design is developed consisting of a moving magnetic circuit of mass M mounted on a spring to convert external vibrations to the active material. Thus, the deformation of the NiMnGa sample can be adjusted by tailoring the design parameters (mass M , sample dimensions, spring constant, etc.) for a given vibration source. The design and …performance of first prototypes are presented showing an output power of 1.5 μW during a single load cycle at an optimum biasing magnetic field of 0.35 T. Show more

Keywords: Vibrational energy harvesting, ferromagnetic shape memory alloy, magneto strain, NiMnGa

DOI: 10.3233/JAE-171038

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 1, pp. 377-383, 2019