2000 Fiscal Year Final Research Report Summary
Study on the Design for Noise Reduction by Applying the Sound Generating Mechanism of a Bell Cricket
| Project/Area Number |
11450067
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
設計工学・機械要素・トライボロジー
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
IWAO Hayashi Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (80016790)
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| Co-Investigator(Kenkyū-buntansha) |
MORIKAWA Koichi Tokyo Institute of Technology, Graduate School of Science and Engineering, Research Associate, 大学院・理工学研究科, 助手 (00282830)
IWATSUKI Nobuyuki Tokyo Institute of Technology, Graduate School of Science and Engineering, Associate Professor, 大学院・理工学研究科, 助教授 (70193753)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Bell cricket / Cricket / Experimental modal analysis / Wing / Finite element method / Noise / Sound generating mechanism / Frequency spectrum |
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| Research Abstract |
It is one of very important issues in our society to solve problems in the field of NVH, such as the vibration, noise, and harshness of machines, and to create a life space which is comfortable to human beings. The optimum design method of machine structures, however, has not been established to inform the operating state of machines with comfortable sounds. This research deals with the sound generating mechanism of a cricket and a bell cricket in order to apply the mechanism to convert the noises of machines into comfortable sounds.The wing motions of a cricket and a bell cricket were observed by a high-speed video camera when the crickets sang and the sequences of singing motion were revealed. The details of the file and rubbing parts on the wings were also revealed by observing with a scanning electron microscopy. The natural modes of flexural vibration of a wing were not only experimentally analyzed by exciting the wing with a piezoactuator and detecting the motion of vibration with a microscopic laser vibrometer but also theoretically calculated by using the FEM models of the wings. The frequency spectra of the sound of the crickets were analyzed by FFT and the main frequencies of major singing ways were then found. The sound generating mechanism of the singing crickets was resultantly found. Finally, the frequency band of a sound pleasing to the ear was obtained by reproducing the sound of the crickets and evaluating the comfortableness.
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