Ahmad Isnikurniawan
Keio University
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Featured researches published by Ahmad Isnikurniawan.
Materials Science Forum | 2014
Ahmad Isnikurniawan; Yasuhiro Fujita; Sachio Tanimoto; Tatsuo Sawada
This paper reports measurement results of ultrasonic propagation velocity in MR fluid under compression. Experiments were conducted by applying different pressures in MR fluid at constant magnetic flux density. At low magnetic flux densities (100 and 200 mT), the ultrasonic propagation velocity in MR fluids changes when subjected to pressure. This change is related to cluster formation in MR fluid. The ultrasonic propagation velocity change is smaller when higher pressures are applied, indicating that cluster size in MR fluid becomes thinner under higher pressures. However, at higher magnetic flux densities (300 and 400 mT), ultrasonic propagation velocities under different pressures are nearly similar. These results indicate that at higher magnetic flux densities, pressures do not affect cluster formation in MR fluids.
International Journal of Applied Electromagnetics and Mechanics | 2014
Yasuhiro Fujita; Ahmad Isnikurniawan; S. Tanimoto; Tatsuo Sawada
An experimental study in ultrasonic propagation characteristics of a magnetic fluid under AC magnetic fields was conducted. Sound velocities in a magnetic fluid increased with elapsed time of the AC magnetic fields. Moreover, rapid decreases in sound velocities in a magnetic fluid were observed when the AC magnetic fields were stopped. These results were similar to those for DC magnetic fields. Dependence of frequencies and magnitudes of AC magnetic fields on sound velocities in a magnetic fluid was observed. Moreover, anisotropy was found in each frequency of the AC magnetic fields.
Materials Science Forum | 2012
Ahmad Isnikurniawan; Yoshitaka Moroka; Hiromichi Ohba; Tatsuo Sawada
The apparent viscosity of magnetorheological (MR) fluids changes in the presence of a magnetic field. The stronger the magnetic field applied, the more the apparent viscosity increases. An increase in the apparent viscosity increases the restriction on the flow of MR fluids. In this study, we perform a qualitative analysis to investigate the effect of a magnetic field on MR fluids under an impact load. An experimental apparatus that consists of a drop-test tower was developed to simulate the impact load, and an MR fluid in a U-pipe was subjected to the impact load via a piston rod. In the experiment, we measured the displacement and velocity of the piston rod. On the basis of the results, the influence of a given magnetic field on the behavior of MR fluids under an impact load is discussed.
International Journal of Applied Electromagnetics and Mechanics | 2014
Ahmad Isnikurniawan; Hiromichi Ohba; Hiro Kaneko; Ryo Yoshizawa; Tatsuo Sawada
International Journal of Applied Electromagnetics and Mechanics | 2012
Yoshitaka Moroka; Ahmad Isnikurniawan; Hiromichi Ohba; Tatsuo Sawada
Magnetohydrodynamics | 2013
Ahmad Isnikurniawan; Yasuhiro Fujita; S. Tanimoto; Tatsuo Sawada
Journal of the Japan Society of Applied Electromagnetics and Mechanics | 2016
Tatsuo Sawada; Takashi Fukumoto; Ahmad Isnikurniawan; Muhammad Agung Bramantya
Magnetohydrodynamics | 2013
Yasuhiro Fujita; Ahmad Isnikurniawan; S. Tanimoto; Tatsuo Sawada
The Proceedings of the Fluids engineering conference | 2012
Yasuhiro Fujita; Ahmad Isnikurniawan; Sachio Tanimoto; Tatsuo Sawada
The Proceedings of Conference of Kanto Branch | 2011
Ahmad Isnikurniawan; Jun Kuroiwa; Yuta Suzuki; Tatsuo Sawada