著者

小松﨑 俊彦 岩田 佳雄

出版者

日本機械学会 = The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集C編 / Nihon Kikai Gakkai Ronbunshu, C Hen / Transactions of the Japan Society of Mechanical Engineers, Part C (ISSN:03875024)

巻号頁・発行日

vol.78, no.786, pp.420-430, 2012-01-01

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In this study, a virtual sound production system is developed where the difference frequency component appears as the secondary audible sound at a point of interference locally by the nonlinear interaction of two independently radiated ultrasounds while they travel directionally and intersect each other. The design of high-directive ultrasonic radiator, followed by the investigation of virtual sound production performance has been done theoretically as well as experimentally. It is known from these investigations that the fairly local sound reproduction in free space is possible, yet the sound pressure level of the secondary field is small. The results have also shown that the generated virtual sound area is dependent on both the difference frequency and the intersection angle of two carrier waves emitted by two sound sources. © 2012 The Japan Society of Mechanical Engineers.

著者

吉田 瑞人 岩田 佳雄 三枝 宏 小松﨑 俊彦

出版者

一般社団法人 日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集

巻号頁・発行日

vol.2018, pp.C-5, 2018

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<p>We prepared 7 cavity-backed disk plates which were same to baseline calibration plate used in COR test. Their membrane thickness increased by 0.2mm from 1.8mm to 3.0mm. CT(Characteristic Time)s were tested by a pendulum test instrument and CORs were measured through COR test using an air gun. The relation between CT and COR agreed with their linear characteristic described in "Technical Description of the Pendulum Test" by R&A and USGA for the thickness of 2.6mm or more. On the other hand, COR was constant and CT only increased for 2.4mm or less. Finally estimation of CT of the plates was simulated. As a result, we show that it is possible.</p>

著者

岩田 佳雄 小松﨑 俊彦 浅沼 春彦 北山 弘樹

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.863, pp.18-00124, 2018 (Released:2018-07-25)

参考文献数

7

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If damping alloy is used as structural material, a structure with high damping performance can be produced and its vibration and noise can be reduced. Damping mechanism of the damping alloy is to convert vibration energy into thermal energy. The damping performance of the damping alloy is not as good as it is used in a dynamic damper. This paper proposes a method of enlarging equivalent loss factor of a damping alloy spring by using a negative spring constant and it is confirmed that the equivalent loss factor of a damping alloy cantilever becomes large by the attraction force of magnet used as the negative spring constant. Optimal design of the dynamic damper which consists of the damping alloy cantilever and a pair of magnets is explained. The vibration suppression effect due to the dynamic damper is demonstrated by means of measuring the compliance and the time history response by impact excitation. The vibration suppression effect depends on the vibrational amplitude due to nonlinearity of the attraction force of magnet but can be sufficiently expected in comparison with the case without the dynamic damper.