Assistant Professor / Department of Mechanical Engineering
Department of Mechanical Engineering
Faculty of Engineering

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Homepage
##### https://kyushu-u.pure.elsevier.com/en/persons/yoshihisa-takayama　Reseacher Profiling Tool　Kyushu University Pure
Phone
092-802-3183
Fax
092-802-0001
Doctor of Engineering
Country of degree conferring institution (Overseas)
No
Field of Specialization
Mechanics and Control Engineering
Total Priod of education and research career in the foreign country
00years00months
Outline Activities
(1) I have been researching the design of some kinds of magnetic dampers: the combined-magnet-type magnetic damper, the magnetic damper applying Halbach magnet array, etc . In addition, I studies the modeling of the magnetic skin effect on magnetic dampers.
(2)I research the reduction of the damage from low-frequency vibration generated by heat pumps, windmills and etc, by applying a high performance magnetic damper or another dampers.

Research
Research Interests
• Modeling of perpendicular-motion-type eddy-current dampers
keyword : Eddy current damper, magnetic damper, gradient of scalar potential, vector potential
2014.04.
• Modeling of parallel-motion-type eddy-current dampers
keyword : Eddy current damper, magnetic damper, gradient of scalar potential, vector potential
2014.04.
Papers
 1 Y. Takayama, S. Kijimoto, S. Ishikawa, Eddy Current Damper Model of Ring Magnet and Coaxially Moving Conducting Disk, IEEE Transactions on Magnetics , 10.1109/TMAG.2021.3058739, 2021.02, An eddy current damper comprising a magnet and a conducting plate moving perpendicularly to it is called a perpendicular-motion-type eddy current damper, whereas one with a magnet and a conducting plate moving parallel to it is called a parallel-motion-type eddy current damper. In this paper, a method of using magnetic vector potentials in a stationary-conductor coordinate system to obtain easily the damping coefficient (the A method) is proposed and applied to a perpendicular-motion-type eddy current damper comprising a ring magnet and conducting disk. The previously proposed coil method is also applied. Because both methods utilize the magnetic flux densities and magnetic vector potentials obtained using a circular current loop, they cannot be considered to be the effect of the magnetic field generated by eddy currents on the damping coefficients. However, the damping coefficients were in good agreement with those obtained using a three-dimensional finite element method (3D-FEM). Hence, the effect of the secondary magnetic field can be ignored. Moreover, the A method is as precise as the 3D-FEM, is less complicated, and does not require an air region and boundary conditions for computation. Additionally, although the errors of the damping ratios calculated from measured data and the A method were 17 %, the error of the modified damping ratios obtained by applying the equivalent mass of the disk to the A method decreased to 6 %.. 2 Modeling of magnetic damper composed of ring magnet and coaxially and relatively moving conducting disk considering skin effect. 3 Yoshihisa Takayama, Takahiro KONDOU, Magnetic Damper Consisting of a Combined Hollow Cylinder Magnet and Conducting Disks, Transactions of the ASME, 10.1115/1.4024094, 135, 051007-1, OCTOBER 2013, Vol. 135 / 051007-1DOI: 10.1115/1.4024094, 2013.10, It is recognized that unstable vibration occurs at a rotating speed above the major criticalspeed by a rotating-conducting-disk type magnetic damper, but not by a rotating-circular-magnet type magnetic damper. In addition, magnetic dampers generally haverelatively poor damping performance. In the present work, two new rotating-circularmagnettype magnetic dampers, (which consist of a combined hollow cylinder magnetwith alternating directional magnetic poles), are introduced and their design method ispresented. Applying the modeling method that the authors have been studying, a prototypemagnetic damper with a combined magnet is fabricated and the damping ratios fromthe analytical results agree well with those from the experimental results. Rotating testsare performed and it is confirmed that unstable vibration does not occur at a rotatingspeed of more than twice the major critical speed. Based on these findings, an optimallydesigned magnetic damper with a combined magnet is developed and a damping ratio of0.25 (damping coefficient of 215 Ns/m) is achieved.. 4 Study on Magnetic Damper Composed of Combined Magnets(Magnetic Damper Composed of Basic Halbach Magnet Arrays). 5 Magnetic Damper Consisting of Circular Coil and Columnar Magnet. 6 Yoshihisa TAKAYAMA Atsuo SUEOKA Takahiro KONDOU, Modeling of Moving-Conductor Type Eddy Current Damper, Journal of System Design and Dynamics, DOI: 10.1299/jsdd.2.1148, Vol.2, No.5, 1148-1159, Vol.2, No.5, 2008, pp.1148-1159[ https://www.jstage.jst.go.jp/article/jsdd/2/5/2_5_1148/_pdf] DOI: 10.1299/jsdd.2.1148, 2008.11. 7 Yoshihisa TAKAYAMA Atsuo SUEOKA Takahiro KONDOU, Magnetic Damper Consisting of Spherical Magnet and Conducting Shell, 12th Asia Pacific Vibration Conference, CD-ROM Paper No.20APVC2007 Program and Abstracts, pp.23, 2007.08. 8 Yoshihisa TAKAYAMA Atsuo SUEOKA and Takahiro KONDOU, Modeling of Eddy Current Damper Composed of Spherical Magnet and Conducting Shell, 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006-13114, 2006.11. 9 Vibration Reduction of a Rotating Machinery by Magnetic Damper with Rotating Circular Magnet(Nonoccurrence of an Unstable Vibration Caused by Magnetic Damping Force), Transactions of the Japan Society of Mechanical Engineering, Series C, Vol.70, No.696 (2004), pp.2195-2202, (in Japanese)[https://www.jstage.jst.go.jp/article/kikaic1979/70/696/70_696_2195/_pdf]. 10 Y. Takayama, A. Sueoka, T. Kondou, Fundamental analysis of magnetic damping force for a rotating machine, Theoretical and Applied Mechanics Japan, Vol.52 (2003), pp.137-144, [ https://www.jstage.jst.go.jp/article/nctam/52/0/52_0_137/_pdf ] , 2003.10. 11 Unstable Vibration of a Rotating Machine Caused by a Magnetic Damping Force, Transactions of the Japan Society of Mechanical Engineering, Series C, Vol.68, No.665 (2002), pp.16-23, (in Japanese)[https://www.jstage.jst.go.jp/article/kikaic1979/68/665/68_665_16/_pdf]. 12 Yoshihisa TAKAYAMA, Atsuo SUEOKA and Takahiro KONDOU, Unstable Vibrations of Rotating Machinery Caused by Magnetic Damper (Experiments and Electric Circuit Model), Proceedings of the Asia-Pacific Vibration Conference '99, Vol.1, (1999), 198 -203, 1999.12. 13 Yoshihisa TAKAYAMA, Atsuo SUEOKA and Shinji FUJIMOTO, Unstable Vibrations of Rotating Machinery Generated in DC Current Electromagnet Field, Proceedings of the Asia-Pacific Vibration Conference '97, Vol.2,1027 -1032, 1997.11.
Presentations
 1 Modeling of Parallel Motion Type Magnetic Damper Composed of Conducting Plate and Magnets with Steel PlatesEddy currents are generated by the relative motion of a conducting plate and a magnet. Magnetic damper is a device that utilizes the magnetic drag force produced by the eddy current. The author call the magnetic damper moving parallel to the conducting disk the parallel-motion type magnetic damper. The author previously proposed the vector potential method for magnetic damper. The method has a good point that magnetic damping force can be calculated accuracy when a parallel-motion type magnetic damper is composed of rectangular magnets with alternating directional magnetic poles and a conducting plate. Generally ferromagnetic metal, for example a steel plate (S45C), has a property known as concentrating magnetic flux into itself. In this paper, using image method, we propose the new vector potential method for the magnetic damper with steel plates outside the rectangular magnets with alternating directional magnetic poles. The image method is a method for calculating a magnetic field by adding image currents in order to satisfy the boundary conditions between a magnetic material area and an air area in the magnetic field and the vector potential field. Damping ratios calculated by the new vector potential method are compared to the tests. As a result, analytical results are in good agreement with the experimental results.. 2 Study on Magnetic Damper Composed of Combined Magnets(Magnetic Damper Composed of Rectangular Magnets). 3 Study on Magnetic Damper Composed of Combined Magnets(Magnetic Damper Composed of Linear Array Magnets). 4 Influence of Magnetic Skin Effect on Magnetic Damper. 5 Study on Magnetic Damper Composed of Combined Magnet. 6 Magnetic Damper consisting of Ball-type Magnet and Conducting Shell. 7 A Magnetic Damper Based on Lorentz Force (Magnetic Damper Consisting of Hollow-Cylindrical Conductor and Ring-Shaped Magnet ). 8 Magnetic Damper Based on Lorentz Force (Experiments and Speculations). 9 Magnetic Damper Using Quadrilateral Magnet. 10 Unstable Vibration of a Rotor caused by a Magnetic Damper.