Thermally Induced Vibration Research Articles

Study of Temperature Behaviour on Thermally Induced Vibration of Non-Homogeneous Trapezoidal Plate with Bi-Linearly Varying Thickness

The main aim of the present work is to study the linear temperature behaviour of a non-homogeneous trapezoidal plate whose thickness varies linearly in both directions. The temperature behaviour considered linear along the length of the plate. Non-homogeneity in plate arises due to variation in density along the length of the plate. The two-term deflection function with clamped-simply supported-clamped-simply supported boundary condition is taken into consideration. The effect of structural parameters such as taper constants, thermal gradient, non-homogeneity constant and aspect ratio has been studied. Rayleigh-Ritz method is used to solve the governing differential equations and to obtain the fundamental frequencies for the first two modes of vibration. Results are presented in graphical form.

Experimental investigation of the thermally induced vibration of a space boom section

Thermally induced vibration (TIV) is a typical failure of large-scale space structures. This paper reports a laboratory experiment that aims to investigate this unusual structural behavior of complex engineering structures. With the help of a Fourier finite element program, the fixing of a space boom section is well designed so that the TIV can be successfully observed. Although the observed torsional vibration mode is different from the bending vibration mode predicted by the classic theory based on a simple beam model, it can be successfully explained by the general thermal structural interaction theory. This demonstrates the validity of the theoretical model and the necessity of using finite element program to analyze complex engineering structures.

Thermally Induced Vibration Analysis of Composite Laminate Based on Equivalent Displacement Method

Thermally induced vibration (TIV) of composite laminate subjected to suddenly applied heating is studied using finite element (FE) method in this paper. Some Python programs written by the authors are used to process the data of the analysis flow, and complete the pre- and post-process of FE models used in the four analyses. An equivalent displacement method is proposed to calculate equivalent temperature load. Dynamic responses of six composite laminates with different sizes are analyzed with solid FE models and shell FE models. The results gotten by FE method are in close proximity to that gotten by classic theory and shear theory under certain conditions. It is proved that the TIV analysis method proposed in this paper is reliable and efficient. The TIV analysis with FE method based on equivalent displacement method can solve the dynamic response of a structure due to sudden changes of temperature or suddenly applied heating.

Non-Linear Thickness Variation on the Thermally-Induced Vibration of a Rectangular Plate: A Spline Technique

The fourth order differential equation, governing the transverse motion of an elastic rectangular plate of a nonlinear thickness variation with a thermal gradient, has been analysed on the basis of classical plate theory employing the Quintic spline interpolation technique. An algorithm for computing the solution of this differential equation is presented for the case of equal intervals. The effect of the thermal gradient, together with taper constants on the natural frequencies of vibration, is illustrated for the first three modes of vibration for C-S-C-S and S-S-S-S rectangular plates.

Measurement of the “IBUKI” Solar Array Panel's Behavior Using High Precision Image Processing

Generally, many space satellites have large solar array panels for power generation and large antennas for observation and communication. The panels and antennas must be lightweight because of the payload weight limit of the launch vehicle. So, they are very flexible, with little damping ability. This results in vibrations cause serious problems. When the thermal environment around a flexible structure on orbit such as a solar array panel changes to cold or hot, the flexible structure produces its own deformation or vibration. These occur most often during rapid temperature changes called thermal snap or thermally-induced vibration, which has been known to cause attitude disturbance in Low Earth Orbit (LEO) satellites. Thermal snap vibration occurring on a flexible solar array panel is very slow. It is very difficult to measure thermal snap motion by sensors such as accelerometer. The behavior of a space structure affected by thermal snap has never been observed directly in space so far. This report presents the measurement results of “IBUKI” solar array panel's behavior using monitor camera.

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

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.

유연 우주구조물의 열적 유기 진동에 관한 연구

본 연구의 목적은 유연 우주구조물이 급격한 열적 환경에 의해 발생되는 진동을 수치적인 계산과 실험을 통해 규명하는데 있다. 단순화한 유연 구조물에 대해 수치적인 접근과 지상 실험실에서 실험한 데이터를 비교 분석하였다. 분석결과 유연 구조물이 급속한 복사 열에 의해 열적 모멘트에 의한 열적 변위가 발생하고 온도의 미소한 주기적 변화로 열 유기 진동이 발생함이 밝혀졌다. 수치해석치와 실험치를 비교한 결과 끝단질량이 없는 경우, 1차 모드 진동수는 0.78Hz로 두 값이 일치하였으나, 끝단 질량이 있는 경우, 끝단 질량이 각각 8g, 16g, 50g, 100g으로 증가할 때 1차 모드의 진동수에 있어 예측치는 1.75Hz, 1.3Hz, 0.87Hz, 0.73Hz이고 실험치는 2.34Hz, 1.5Hz, 0.78Hz, 0.78Hz로 감소하는 경향을 보이며 비록 예측치가 단순화 공식을 이용함에도 불구하고 실험치에 근접하였다. The purpose of this study is to analyze the phenomena of the thermally-induced vibration for the flexible space structure due to abrupt change of radiation heating circumstance using the numerical analyze and experiment test. In order to verify this structure, numerical approaches on the simplified flexible tube were compared with experimental test results at the ground experimental facility. In this analyze, it was found that the thermal deformation occurs firstly due to fast radiation heating of flexible structure and then the thermally-induced vibration would be induced due to small periodic change of temperature. According to comparison of numerical and experimental results, in case of no tip mass, the first mode vibration by the numerical analyze was a.78Hz same as that of the experimental result. However in case of increase tip-masses of 8g, 16g, 50g and 100g, the first modes vibration theoretical analyze were 1.75Hz, I.3Hz, a.87Hz and 0.73Hz, in decrease trend respectively and those by experimental test were 2.34Hz, 1.5Hz, 0.78Hz and 0.78Hz in decrease trend respectively. Although using the simpled equation for the estimation, the estimation results were similar to experimental results.

Structural design optimization on thermally induced vibration

AbstractThe numerical method of design optimization for structural thermally induced vibration is originally studied in this paper and implemented in the software JIFEX. The direct and adjoint methods of sensitivity analysis for thermal‐induced vibration coupled with both linear and non‐linear transient heat conduction is firstly proposed. Based on the finite element method, the linear structural dynamics is treated simultaneously with linear and non‐linear transient heat conduction. In the heat conduction, the non‐linear factors include the radiation and temperature‐dependent materials. The sensitivity analysis of transient linear and non‐linear heat conduction is performed with the precise time integration method; and then, the sensitivity analysis of structural transient responses is performed by the Newmark method. Both the direct method and the adjoint method are employed to derive the sensitivity equations of thermal vibration. In the adjoint method, two adjoint vectors of structure and of heat conduction are used to derive the adjoint equations. The coupling effect of heat conduction on thermal vibration in the sensitivity analysis is particularly investigated. With the coupling sensitivity analysis, the optimization model is constructed and solved by the sequential linear programming or sequential quadratic programming algorithm. Numerical examples are given to validate the proposed methods and to demonstrate the importance of the coupled design optimization. Copyright © 2003 John Wiley & Sons, Ltd.

Thermally-induced vibrations of a spinning spacecraft boom

An analytical study of thermally-induced motions is presented for a beam model of an axial boom of a spin-stabilized spacecraft. The study includes: (1) an uncoupled thermal-structural analysis which assumes that the temperature distribution is independent of the deflections of the boom and (2) a coupled thermal-structural analysis which includes the dependence of the incident heat flux and temperature distribution on the boom's deflected position. In the uncoupled analysis, a steady-state thermal response is determined. The resulting temperature gradient causes stable bending motions which are determined by modal expansion. The coupled analysis assumes a deflected shape and determines governing equations for an approximate response. The stability of the coupled response is studied using Floquet theory. The results show that unstable thermally-induced vibrations are possible for parameters characteristic of a typical spacecraft's axial boom.

Maximum Response of Missiles due to Inertial Asymetry

References , ^ugusti, G., Comment on 'Thermally Induced Vibration and Flutter of Flexible Booms,' of Spacecraft and Rockets, Vol. 8, Feb. 1971, pp. 202-204. 2 Jordan, P.P., Comment on Thermally Induced Vibration and Flutter of a Flexible Boom,' Journal of Spacecraft and Rockets, Vol. 8, Feb. 1971, pp. 204-205. Etkin, B. and Hughes, P.C., Explanation of the Anomalous Spin Behavior of Satellites with Long Flexible Antennae, Journal of Spacecraft and Rockets, Vol. 4, Sept. 1967, pp. 1139-1145. Yu, Y.Y., Reply by Author to P.P. Jordan and G. Augusti and New Results of Two-Mode Approximation Based on a Rigorous Analysis of Thermal Bending Flutter of a Flexible Boom, Journal of Spacecraft and Rockets, Vol. 8, Feb. 1971, pp. 205-208. Farrell, J.L. and Newton, J.K., Continuous and Discrete RAE Structural Models, Journal of Spacecraft and Rockets, Vol. 6, April 1969, pp. 414-423. Farrell, J.L., Newton, J.K., Miller, J.A., and Solomon, E.N., Optimal Estimation of Rotation Coupled Flexural Oscillations, Journal of Spacecraft and Rockets, Vol. 6, Nov. 1969, pp. 1290-1298.