• Title/Summary/Keyword: Non-vibration

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Nonlinear vibration analysis of laminated plates resting on nonlinear two-parameters elastic foundations

  • Akgoz, Bekir;Civalek, Omer
    • Steel and Composite Structures
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    • v.11 no.5
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    • pp.403-421
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    • 2011
  • In the present manuscript, geometrically nonlinear free vibration analysis of thin laminated plates resting on non-linear elastic foundations is investigated. Winkler-Pasternak type foundation model is used. Governing equations of motions are obtained using the von Karman type nonlinear theory. The method of discrete singular convolution is used to obtain the discretised equations of motion of plates. The effects of plate geometry, boundary conditions, material properties and foundation parameters on nonlinear vibration behavior of plates are presented.

A Study on the Non-linear Forced Torsional Vibration for Propulsion Shaftings with Multi-Degree-of-Freedom System (기관축계의 비선형 다자유도 강제 비틀림진동에 관한 연구)

  • 김수철;이문식;장민오;김의간
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.6
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    • pp.7-14
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    • 2000
  • Nowadays, the viscous damper using high viscosity oil was much to be used for engine shafting system to reduce the excessive additional stress by torsional vibration. In general, it was assumed that the viscous damper could be modelled having only damping coefficient, that is to say, whose stiffness be ignored. But it is found that there exists a jump phenomenon, as a kind of non-linear vibration, in the actual engine shafting system with a damper of high viscosity. Therefore the damper ring and the casing are modelled as two mass elastic system with a complex viscosity. Also, to analyze a non-linear phenomenon, it is assumed that the viscous damper has a linear stiffness coefficient in proportion to the angular amplitude and a non-linear stiffness coefficient in proportion to cube of the angular amplitude. For the analysis, Quasi-Newton method with BFGS(Broyden-Fletcher-Goldfarb-Shanno) formula is used. Both calculated and measured values are provided in this paper which confirm the possibility of applying non-linear theory to engine shafting system with viscous damper.

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Studies on the Nutrition under Abnormal Environment(I) -Nutrition under Vibration- (이상환경하(異常環境下)의 영양문제(營養問題) 연구(硏究)(제1보) -진동하(振動下)의 영양문제(營養問題)-)

  • Yu, Jong-Yull
    • Journal of Nutrition and Health
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    • v.4 no.4
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    • pp.15-23
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    • 1971
  • On the assumption that the supplementation of certain nutrients or foods to the rice diet (low protein, low fat, and low vitamins) may decrease, to some extent, the degree of suffering from abnormal environments, such as vibration, noises, gases, dusts, smog etc. a series of experiments were started. As the first report the nutrition under vibration was studied in this experiment. Sixty (60) young growing male rats weighing about 65 grams were used, grouping to five (5) groups, twelve (12) rats each group. They were fed on the following five (5) experimental diets: rice diet (basal diet), rice diet+casein, rice diet+vitamins, rice $diet+{\alpha}-tocopherol$, and rice diet+ginseng powder (see the tables 1 and 2) for the period of 14 weeks experiment. During the experiment period the half number of the rats of each group were exposed to the three (3) hours vibration every day. The protective effect of each diet against the vibration may be summarized as follows. 1. The growth of rice diet group was impaired significantly under vibration, However, those of other groups (protein-supplemented, vitamin-supplemented, ${\alpha}-tocopherol-supplemented$ and ginseng-supplemented groups) were impaired much less compared with rice diet group. 2. The feed efficiency of the rice diet group was decreased significantly under vibration. It is estimated that the biological availability of nutrients was impaired under this environment. On the other hand, the feed efficiencies of protein supplemented, of vitamin supplemented, and of ginseng supplemented groups were not decreased under vibration, statistically. 3. There is tendency that the food spillages of vibration groups are higher than those of non-vibration groups. Especially it seems true in the case of rice diet group. The food spillage may be, to some extent, related with mental nervousness of animals. From the point that the food spillage of ginseng supplemented group is significantly lower than those of other groups it is thought ginseng acts some good role in protecting nervous system from suffering from vibration. 4. In all groups except protein supplemented group, liver fat of vibration group tends to be higher than that of non-vibration group. 5. It shows that, in general, the serum alkaline phosphatase activity of the vibration group is significantly higher than that of the non-vibration group. It seems that there may be, to some extent, corelation between the amount of liver fat and serum alkaline phosphatase activity. 6. There is tendency that, in rice diet group, the organs of vibration group are smaller than those of non-vibration group, especially lung is so. It is thought that this may be due to the poor growth of whole body size in vibration group.

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A Study of Mathematical Human Modeling of Sitting Crew during Whole-body Vibration (해상 근무 승무원의 수학적 전신진동 해석 모델에 관한 연구)

  • Kim, Hee-Seok;Kim, Hong-Tae;Park, Jin-Hyoung
    • Journal of the Ergonomics Society of Korea
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    • v.22 no.1
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    • pp.1-15
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    • 2003
  • The resonance behaviour needs be understood to identify the mechanisms responsible for the dynamic characteristics of human body, to allow for the non-linearity when predicting the influence of seating dynamics, and to predict the adverse effects caused by various magnitudes of vibration. However, there are currently no known studies on the effect of vibration magnitude on the transmissibility to thoracic or lumbar spine of the seated person, despite low back pain(LBP) being the most common ailment associated with whole-body vibration. The objective of this paper is to develop a proper mathematical human model for LBP and musculoskeletal injury of the crew in a maritime vehicle. In this study, 7 degree-of-freedom including 2 non-rigid mass representing wobbling visceral and intestine mass, is proposed. Also, when compared with previously published experimental results, the model response was found to be well-matching. When exposed to various of vertical vibration, the human model shows appreciable non-linearity in its biodynamic responses. The relationships of resonance for LBP and musculoskeletal injury during whole-body vibration are also explained.

Empirical decomposition method for modeless component and its application to VIV analysis

  • Chen, Zheng-Shou;Park, Yeon-Seok;Wang, Li-ping;Kim, Wu-Joan;Sun, Meng;Li, Qiang
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.2
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    • pp.301-314
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    • 2015
  • Aiming at accurately distinguishing modeless component and natural vibration mode terms from data series of nonlinear and non-stationary processes, such as Vortex-Induced Vibration (VIV), a new empirical mode decomposition method has been developed in this paper. The key innovation related to this technique concerns the method to decompose modeless component from non-stationary process, characterized by a predetermined 'maximum intrinsic time window' and cubic spline. The introduction of conceptual modeless component eliminates the requirement of using spurious harmonics to represent nonlinear and non-stationary signals and then makes subsequent modal identification more accurate and meaningful. It neither slacks the vibration power of natural modes nor aggrandizes spurious energy of modeless component. The scale of the maximum intrinsic time window has been well designed, avoiding energy aliasing in data processing. Finally, it has been applied to analyze data series of vortex-induced vibration processes. Taking advantage of this newly introduced empirical decomposition method and mode identification technique, the vibration analysis about vortex-induced vibration becomes more meaningful.

Vibration Analysis of Bladed Disk using Non-contact Blade Vibration System

  • Joung, Kyu-Kang;Han, Chak-Heui;Kang, Suk-Chul;Kim, Yeong-Ryeon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.871-876
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    • 2008
  • The blade vibration problem of bladed disk is the most critical subject to consider since it directly affects the stable performance of the engine as well as life of the engine. Especially, due to complicated vibration pattern of the bladed disk, more effort was required for vibration analysis and test. The research of measuring the vibration of the bladed disk, using NSMS(Non-intrusive stress measurement) instead of Aeromechanics testing method requiring slip ring or telemetry system with strain gauge, was successful. These testing can report the actual stresses seen on the blades; detect synchronous resonances that are the source of high cycle fatigue(HCF) in blades; measure individual blade mis-tuning and coupled resonances in bladed disks. In order to minimize the error being created due to heat expansion, the tip timing sensor is installed parallel to the blade trailing edge, yielding optimal result. Also, when working on finite element analysis, the whole bladed disk has gone through three-dimensional analysis, evaluating the family mode. The result of the analysis matched well with the test result.

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Tunnel Blasting case by Combination of Electronic Detonator and Non-electric Detonator (전자뇌관과 비전기뇌관을 조합한 터널발파 시공사례)

  • Lee, Min Su;Kim, Hee Do;Lee, Hyo;Lee, Jun Won
    • Explosives and Blasting
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    • v.36 no.1
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    • pp.34-38
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    • 2018
  • It proceed the trial test by applying blasting system with combination of electronic detonator and non-electric detonator(Supex Blasting Method) for the purpose of preventing the over-break as well as controling the blasting vibration and noisy at the site of Boseong-Imseongri railroad section ${\bigcirc}{\bigcirc}$. As a result of that, the blasting vibration and noisy was measured within the allowable standard of vibration. In conclusion, the combination of electronic detonator and non-electric detonator can not only reduce come construction cost, level of vibration and noisy but also get the prevention effect for Public resentment and minimize the rock-damage through over break control.

Vibration Characteristics and Performance of Cantilever for Non-contact Atomic Force Microscopy (비접촉 원자간력 현미경의 탐침 캔틸레버 진동 특성 및 측정 성능 평가)

  • 박준기;권현규;홍성욱
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.6
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    • pp.495-502
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    • 2004
  • This paper presents the vibration analysis and the performance evaluation of cantilevers with probing tips for non-contact scanning probe microscopy. One of the current issues of the scanning probe microscopy technology is to increase the measurement speed, which is closely tied with the dynamic characteristics of cantilevers. The primary concern in this research is to investigate the relation between the maximum possible speed of non-contact scanning probe microscopy and the dynamic characteristics of cantilevers. First, the finite element analysis is made for the vibration characteristics of various cantilevers in use. The computed natural frequencies of the cantilevers are in good agreement with measured ones. Then, each cantilever is tested with topographic measurement for a standard sample with the scanning speed changed. The performances of cantilevers are analyzed along with the natural frequencies of cantilevers. Experiments are also performed to test the effects of how to attach cantilevers in the piezo-electric actuator. Finally, measurement sensitivity has been analyzed to enhance the performance of scanning probe microscopy.

Performance Evaluation of Non-contact Atomic Force Microscopy Due to Vibration Characteristics of Cantilever (비접촉 원자간력 현미경의 탐침 외팔보 진동특성에 따른 성능 평가)

  • 박준기;권현규;홍성욱
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.263-268
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    • 2003
  • This paper presents a result of performance evaluation fur non-contact scanning probe microscopy with respect to the vibration characteristics of cantilevers with tips. One of the current issues of the scanning probe microscopy technology is to increase the measurement speed, which is closely tied with the dynamic characteristics of cantilevers. The primary concern in this research is to investigate the relation between the maximum possible speed of non-contact scanning probe microscopy and the dynamic characteristics of cantilevers. First, the finite element analysis is made fur the vibration characteristics of various cantilevers in use. The computed natural frequencies of the cantilevers are in good agreement with measured ones. Then, each cantilever is tested with topographic measurement for a standard sample with the scanning speed changed. The performances of cantilevers are analyzed along with the natural frequencies of cantilevers. Experiments are also performed to test the effects of how to attach cantilevers in the piezo-electric actuator. Finally, measurement sensitivity has been analyzed to enhance the performance of scanning probe microscopy.

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