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RISS 인기검색어
- 검색키워드
- 저자 : Abdul Ghaffar Abdul Rahman (검색결과 2 건)
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Similitude study of an in-service industrial piping system under high flow induced vibration
Yap Huey Tyng,Ong Zhi Chao,Kong Keen Kuan,Zubaidah Ismail,Abdul Ghaffar Abdul Rahman,Chong Wen Tong 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
Flow induced vibration problem of an in-service duplex stainless steel piping system was investigated in previous research. The investigation required multiple sets of site measurement results at the offshore gas processing platform which raises the concerns of safety and its practicality. A lab scale of the mentioned piping system is preferable to study the flow induced vibration problem at different operating conditions to better understand the dynamic behaviour of this piping system. In addition, most of the dimensional analyses were performed either solely on structure or fluid system. System with flow induced vibration problem has never been attempted and thus it is important to perform similitude study of the piping system prior to fabrication of the lab scale model. Buckingham Pi theorem was applied and the similitude was verified by computational mechanics both qualitatively and quantitatively. The calculated non-dimensional variables of a scaled piping system in describing the flow characteristics which contribute to the structure deformation give similar scale factor, flow pattern and flow induced dynamic deformation and stress in this fluid-structure interacted piping system indicating that geometric, kinematic and dynamics similarity are achieved.
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Ong Zhi Chao,Lim Hong Cheet,Khoo Shin Yee,Abdul Ghaffar Abdul Rahman,Zubaidah Ismail 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.8
A novel method called Impact-synchronous modal analysis (ISMA) was proposed previously which allows modal testing to be performed during operation. This technique focuses on signal processing of the upstream data to provide cleaner Frequency response function (FRF) estimation prior to modal extraction. Two important parameters, i.e., windowing function and impact force level were identified and their effect on the effectiveness of this technique were experimentally investigated. When performing modal testing during running condition, the cyclic loads signals are dominant in the measured response for the entire time history. Exponential window is effectively in minimizing leakage and attenuating signals of non-synchronous running speed, its harmonics and noises to zero at the end of each time record window block. Besides, with the information of the calculated cyclic force, suitable amount of impact force to be applied on the system could be decided prior to performing ISMA. Maximum allowable impact force could be determined from nonlinearity test using coherence function. By applying higher impact forces than the cyclic loads along with an ideal decay rate in ISMA, harmonic reduction is significantly achieved in FRF estimation. Subsequently, the dynamic characteristics of the system are successfully extracted from a cleaner FRF and the results obtained are comparable with Experimental modal analysis (EMA).
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