Frequency Response Analysis of A Small Satellite Structure Under Random Vibration Acceleration Loads Using Mode Superposition Method

Hamid Emami and Foad Farhani

Department of Mechanical Engineering, Iranian Research Organization for Science and Technology (I.R.O.S.T), P.O. Box: 15815-3538, Tehran (Iran).

DOI : http://dx.doi.org/10.13005/msri/060106

ABSTRACT:

Launch event imposes critical loading conditions on the space flight hardware. Space structures are exposed to different environments and consequently the space vehicle experiences various loading conditions. The random vibration load, which is inputted mechanically and acoustically from rocket engines, is one of the major loads which must be considered in payload flight hardware structures. In this study two different approaches for calculating the frequency response of a small satellite structure under random vibration acceleration loads have been considered. These approaches are based on frequency response analysis using modal effective modes and effective masses related to these modes, and finite element spectrum analysis. The first approach considers the overall behavior of the structure. On the other hand, the second approach reveals the response of the structure on each desired node. The results of the first approach are dependent on the number of selected modes, and effective masses related to the modes. The analyses for small satellites show that the application of superposition technique can result in an appreciable reduction in the calculation time, and helps in finding points on the structure, which show the behavior of the center of gravity during the tests. In addition, it may also be used as approximation for modeling of satellite behavior, treated as concentrated mass, during the quick analyses at the preliminary design, and for the satellite and launcher coupled analyses. The analyses show that the satellite behavior under the effect of local modes can be different. This increases the error in this approach, especially for larger structures, which have structure elements with greater inertial effects and consequently higher local effective masses. This approach also predicts the equivalent static load based on root mean square (rms) calculation of power spectral density response. This paper also considers the influence of effective mode selection criteria on the rms value of the response.

KEYWORDS: Random vibration; modal effective mass; structural dynamics; space structures

Copy the following to cite this article: Emami H, Farhani F. Frequency Response Analysis of A Small Satellite Structure Under Random Vibration Acceleration Loads Using Mode Superposition Method. Mat.Sci.Res.India;6(1)

Copy the following to cite this URL: Emami H, Farhani F. Frequency Response Analysis of A Small Satellite Structure Under Random Vibration Acceleration Loads Using Mode Superposition Method. Mat.Sci.Res.India;6(1). Available from: http://www.materialsciencejournal.org/?p=3412

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