• Title/Summary/Keyword: thermal vibration

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Verification of Thermal Characteristics and Overturning Moment for Lateral Vibration System (수평가진 시스템의 열 특성 및 모멘트 성능 검증)

  • Eun, Hee-Kwang;Im, Jong-Min;Moon, Sang-Moo;Moon, Nam-Jin;Lee, Dong-Woo;Choi, Seok-Weon
    • Aerospace Engineering and Technology
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    • v.8 no.2
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    • pp.113-121
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    • 2009
  • Shaker system is used to simulate the vibration from the launch environment. The vibration tests are performed in the vertical and lateral direction. For the lateral vibration test, the slip table system is used with shaker system. For the latest large satellite, vibration test adaptor is made of the steel. But slip table of lateral vibration is made of magnesium, so there is big difference of thermal expansion ratio between slip table and vibration test adaptor. This paper encompasses the following items; verification process of thermal characteristics and overturning moment and a solution for lateral vibration test with steel vibration test adaptor.

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Study on Comparison of Atmospheric and Vacuum Environment of Thermally-Induced Vibration Using Vacuum Chamber

  • Kong, Chang-Duk;Park, Hyun-Bum;Lee, Ha-Seaung
    • International Journal of Aeronautical and Space Sciences
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    • v.11 no.1
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    • pp.26-30
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    • 2010
  • The present paper studies the thermally-induced vibration phenomenon of the flexible space boom structure. In order to simulate the thermally-induced vibration phenomenon of the flexible thin boom structure of the spacecraft with the attached tip mass in space, the thermally-induced vibration including thermal flutter is experimentally investigated at various thermal environments using a heating lamp in vacuum chamber. In this experimental study, fluctuating characteristics, natural frequency and thermal strains of the thermally-induced vibration are parametrically investigated at various thermal environment conditions. Finally the thermally-induced vibration of the flexible boom structure of the orbiting earth satellite in solar radiation environment from the earth eclipse region including umbra and penumbra is simulated using the power control of the heating lamp in the vacuum chamber.

On Vibration Characteristics Study of Thermo-Visco-Plastic Material Under Periodic Thermal Loading (반복적 열하중을 받는 열탄점소성 구조물의 진동 특성 연구)

  • 김덕관;김승조
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.49-54
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    • 1997
  • In this paper, vibration characteristics are considered about thermo-visco-plastic material under periodic thermal loading. When in high temperature region, thermo-visco-plastic structure has a periodic thermal loading, it is very important in an accumulated structure like a spacestation to investigate vibration characteristic, stress-strain characteristic is considered in various 2-D model by finite element method.

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Experimental Study on Thermal Characteristics for Gap Sensor (Gap 센서의 열 특성에 관한 연구)

  • Koo, Jae-Raeyang;Lee, Doo-Young;Kim, Doo-Young;Lee, Dae-Sung;Kim, Sung-Hwi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.790-793
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    • 2005
  • Gap Sensor is widely used to measure vibration in power plant. In general the result of the vibration measurement may have special error due to two thermal characteristics of gap sensor such as sensitivity shift and zero shift. Thermal sensitivity is change of linearity and thermal zero shift is chang of offset. It is investigated two thermal characteristics for Rap son or in this paper.

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Effect of non-uniform temperature distributions on nonlocal vibration and buckling of inhomogeneous size-dependent beams

  • Ebrahimi, Farzad;Salari, Erfan
    • Advances in nano research
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    • v.6 no.4
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    • pp.377-397
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    • 2018
  • In the present investigation, thermal buckling and free vibration characteristics of functionally graded (FG) Timoshenko nanobeams subjected to nonlinear thermal loading are carried out by presenting a Navier type solution. The thermal load is assumed to be nonlinear distribution through the thickness of FG nanobeam. Thermo-mechanical properties of FG nanobeam are supposed to vary smoothly and continuously throughout the thickness based on power-law model and the material properties are assumed to be temperature-dependent. Eringen's nonlocal elasticity theory is exploited to describe the size dependency of nanobeam. Using Hamilton's principle, the nonlocal equations of motion together with corresponding boundary conditions based on Timoshenko beam theory are obtained for the thermal buckling and vibration analysis of graded nanobeams including size effect. Moreover, in following a parametric study is accompanied to examine the effects of the several parameters such as nonlocal parameter, thermal effect, power law index and aspect ratio on the critical buckling temperatures and natural frequencies of the size-dependent FG nanobeams in detail. According to the numerical results, it is revealed that the proposed modeling can provide accurate frequency results of the FG nanobeams as compared some cases in the literature. Also, it is found that the small scale effects and nonlinear thermal loading have a significant effect on thermal stability and vibration characteristics of FG nanobeams.

Robust-Optimal Vibration Control of a Beam Using Thermal Stress (열응력을 이용한 보의 강인-최적 진동제어)

  • 권태철;이우식;김진걸
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1993.10a
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    • pp.232-239
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    • 1993
  • The vibration damping of structure is increased by thermal actuator. The thermal actuator causes thermal stress across the section of structure. The several kinds of control theories are proposed and the proposed control theories are successful in increasing vibration damping. This scheme can be effectively applied to large space structure [LSS] having very low natural frequencies.

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Thermal Design of Cryogenic Compressor with Strategies for Keeping Performance of Micro-vibration Isolation System (미소진동저감용 진동절연기의 성능유지를 위한 극저온 냉각용 압축기 조립체 열제어 설계)

  • Oh, Hyun-Ung;Lee, Kyung-Joo;Jeong, Suk-Yong;Shin, So-Min
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.3
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    • pp.237-242
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    • 2012
  • Spaceborne pulse tube-type cryogenic compressors are widely used for space applications. To guarantee cooling performance of the compressor, mission life time and micor-vibration stability, suitable thermal control of compressor is required. Micro-vibration of the compressor is the one of the sources to degrade the pointing performance of observation satellite. In the present work, on-orbit thermal design of compressor in order not to degrade the performance of micro-vibration isolation system keeping the thermal control performance has been proposed and investigated through thermo-mechanical analysis.

Thermal-induced nonlocal vibration characteristics of heterogeneous beams

  • Ebrahimi, Farzad;Barati, Mohammad Reza
    • Advances in materials Research
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    • v.6 no.2
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    • pp.93-128
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    • 2017
  • In this paper, thermal vibration behavior of nanoscale beams made of functionally graded (FG) materials subjected to various types of thermal loading are investigated. A Reddy shear deformation beam theory which captures both the microstructural and shear deformation effects without the need for any shear correction factors is employed. Material properties of FG nanobeam are assumed to be temperature-dependent and vary gradually along the thickness according to the power-law form. The influence of small scale is captured based on nonlocal elasticity theory of Eringen. The nonlocal equations of motion are derived through Hamilton's principle and they are solved applying analytical solution. The comparison of the obtained results is conducted with those of nonlocal Euler-Bernoulli beam theory and it is demonstrated that the proposed modeling predict correctly the vibration responses of FG nanobeams. The effects of nonlocal parameter, material graduation, mode number, slenderness ratio and thermal loading on vibration behavior of the nanobeams are studied in detail.

A nonlocal integral Timoshenko beam model for free vibration analysis of SWCNTs under thermal environment

  • Liani, Mohamed;Moulay, Noureddine;Bourada, Fouad;Addou, Farouk Yahia;Bourada, Mohamed;Tounsi, Abdelouahed;Hussain, Muzamal
    • Advances in materials Research
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    • v.11 no.1
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    • pp.1-22
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    • 2022
  • In this paper, the nonlocal integral Timoshenko beam model is employed to study the free vibration characteristics of singled walled carbon nanotubes (SWCNTs) including the thermal effect. Based on the nonlocal continuum theory, the governing equations of motion are formulated by considering thermal effect. The influences of small scale parameter, the chirality of SWCNTs, the vibrational mode number, the aspect ratio of SWCNTs and temperature changes on the thermal vibration properties of single-walled nanotubes are examined and discussed. Results indicate significant dependence of natural frequencies on the nonlocal parameter, the temperature change, the aspect ratio and the chirality of SWCNTs. This work should be useful reference for the application and the design of nanoelectronics and nanoelectromechanical devices that make use of the thermal vibration properties of SWCNTs.