- 著者
- Nobuyuki IWATSUKI Koichi MORIKAWA
- 出版者
- 一般社団法人 日本機械学会
- 雑誌
- Journal of System Design and Dynamics (ISSN:18813046)
- 巻号頁・発行日
- vol.2, no.2, pp.596-609, 2008 (Released:2008-05-30)
- 参考文献数
- 8
- 被引用文献数
- 1 1
A frog shaped guiro is a wooden percussion instrument with an open-ended cave. By rubbing dorsal fins like saw blades on a back of the guiro with a wooden stick, the guiro generates the sound like a frog's voice. The exciting force, response acceleration and radiating sound pressure were measured with accelerometers on the stick and guiro and a condenser microphone and then the relation between the impulsively exciting force and sound pressure was revealed. A three-dimensional solid model of the guiro was built by use of an X-ray CT scanner device and a finite element model composed of tetrahedral elements was then obtained. The FEM modal analysis revealed that the frog shaped guiro had four dominant modes of vibration which was characterized by motion of mouth of the guiro such as the yawn mode and grinding teeth mode. The frequency spectrum of the sound pressure radiating from the frog shaped guiro excited by sequential impulsive forces moving along the dorsal fins was theoretically estimated. Since the estimated sound pressure agreed well with the measured one, the sound radiating from the guiro like a frog's voice could be reproduced. It was also revealed that the variation of driving point mobility of the dorsal fins and amplitude of the exciting force affected to generate the sound like a frog's voice.
- 著者
- Junji YOSHIDA Nobuyuki KAWAGOE Tomohiro KAWAMURA
- 出版者
- 一般社団法人 日本機械学会
- 雑誌
- Journal of System Design and Dynamics (ISSN:18813046)
- 巻号頁・発行日
- vol.7, no.3, pp.293-303, 2013 (Released:2013-09-30)
- 参考文献数
- 18
- 被引用文献数
- 2
Bicycles are popular with the general public because of their low price and easy maintenance, and they will be an important vehicle in the future because of their low environmental load. Improving the comfort of the ride is one of the important factors that will lead to increased popularity. We attempted to increase comfort by reducing vibration, and evaluated the results with a subjective test. We determined that low frequency vibration of the seat greatly affected the comfort of the ride. We then performed a transfer path analysis (TPA) and a hammering test to investigate how the vibration characteristics of the bicycle affected the vibration of the seat. Through TPA, the rear of the bicycle frame was found to have a high influence on the seat vibration, and the vibration behavior was obtained by modal analysis. In order to reduce seat vibration, a spring was inserted in the front of the seat and, to increase the stiffness, a steel plate and bolts were attached to the rear of the frame. As a result, the seat vibration while riding was decreased by about 10 dB, and the comfort of the ride was greatly improved.
- 著者
- Kazuto MIYAWAKI Shigeki MORI Akira SAKURADA Akihiro NAGANAWA Yuki KIMURA Yotsugi SHIBUYA Goro OBINATA
- 出版者
- 一般社団法人 日本機械学会
- 雑誌
- Journal of System Design and Dynamics (ISSN:18813046)
- 巻号頁・発行日
- vol.5, no.4, pp.513-522, 2011 (Released:2011-06-20)
- 参考文献数
- 13
- 被引用文献数
- 1
Highly precise positioning control is based on mechatronics. Nanotechnology, especially nanometer positioning technology with high-speed and robust positioning feedback control, is used in various technical fields including measuring systems, magnetic recording and the semiconductor industry. To date, various actuator systems have been proposed, but the structural models have working distance of either less than a millimeter or more than ten millimeters. A structural model with working distance of several millimeters has not been reported in the relevant literature. We propose an actuator structural design that would enable production of actuator systems with such working distances. This actuator has a voice coil motor and a new guide with an elastic support mechanism consisting of a special spring that is restricted to movement in only one direction. This ESM causes no lost motion, friction with motion, or mechanical play. The voice coil motor thrusts and displaces the elastic support mechanism linearly. Therefore, highly precise positioning control can be realized using a simple controller. This paper describes evaluation of the positioning control method from the displacement of ESM and presents basic data for development of future nano-actuator systems.