• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.277-283
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• 2003

It is well known that the natural frequencies of the pipe come to be lower as internal fluid velocity and pressure increase, and the pipe will be unstable if the fluid velocity is higher than critical velocity. But even if the velocity of the fluid below the critical velocity, resonance will be caused by pulsation of the fluid. So it should be also taken into consideration that the effect of pulsating fluid in pipe design. The research of the piping system vibration due to a fluid pulsation has been studied by many people. But almost is dealt with determining the boundary between stable and unstable region without analyzing forced response in the stable region. In this study, not only stability analysis but also forced response analysis, which is caused by harmonically excited fluid especially, is conducted.

• 한국군사과학기술학회지
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• 제8권1호
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• pp.81-91
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• 2005

It is well known that the natural frequencies of the pipe come to be lower as internal fluid velocity and pressure increase, and the pipe will be unstable if the fluid velocity is higher than critical velocity. But even if the velocity of the fluid below the critical velocity, resonance will be caused by pulsation of the fluid. So the effects of pulsating fluid in pipe should be also taken into consideration for better analysis. The research of the vibration of piping system due to a fluid pulsation has been studied by many people. But most of them are dealt with determining the boundary between stable and unstable region without analyzing forced response in the stable region. In this study, not only stability analysis but also forced response analysis, which is caused by harmonically excited fluid especially, is conducted. In order to analyze the system numerically, the descretized equation is formulated by using FEM(Finite Element Method). And the results of this method are compared with those of AMM(Assumed Mode Method) which were used by many researcher earlier.

• Advances in nano research
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• 제9권4호
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• pp.263-276
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• 2020

In this article, the acoustic responses of free vibrated natural fibre-reinforced polymer nanocomposite structure have been investigated first time with the help of commercial package (ANSYS) using the multiphysical modelling approach. The sound relevant data of the polymeric structure is obtained by varying weight fractions of the natural nanofibre within the composite. Firstly, the structural frequencies are obtained through a simulation model prepared in ANSYS and solved through the static structural analysis module. Further, the corresponding sound data within a certain range of frequencies are evaluated by modelling the medium through the boundary element steps with adequate coupling between structure and fluid via LMS Virtual Lab. The simulation model validity has been established by comparing the frequency and sound responses with published results. In addition, sets of experimentation are carried out for the eigenvalue and the sound pressure level for different weight fractions of natural fibre and compared with own simulation data. The experimental frequencies are obtained using own impact type vibration analyzer and recorded through LABVIEW support software. Similarly, the noise data due to the harmonically excited vibrating plate are recorded through the available Array microphone (40 PH and serial no: 190569). The numerical results and subsequent experimental comparison are indicating the comprehensiveness of the presently derived simulation model. Finally, the effects of structural design parameters (thickness ratio, aspect ratio and boundary conditions) on the acoustic behaviour of the natural-fibre reinforced nanocomposite are computed using the present multiphysical model and highlighted the inferences.