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VIBES: Visionary Ingenuity Boosting European Spacecraft. Managing microvibrations for the future of spaceflight

100%

Garcia A. , Gust T. , Basata E. , Gersting T. , Deka M. , Thiele S. , Salah M. , Koerner M. B. , Runte T. , Gonzalez M.

Archive of Mechanical Engineering

2023

tom LXX, nr 2

183--197

Microvibrations are mechanical oscillations caused by components such as the reaction wheels of an attitude control system of a spacecraft. These microvibrations are transferred through the spacecraft structure onto important instruments (e.g., optical instruments), causing those to produce diminished results (e.g., reduced image quality, imprecise geolocation etc.). At the present state, microvibrations in spacecraft cannot be actively controlled because their very high frequencies of up to 1000 Hz are above the control bandwidth a current attitude control system can provide. However, being able to reduce the effects of microvibrations on a space mission is becoming increasingly more critical as the envelope of future optical satellite missions expands. Furthermore, the advancements made in the performance of small satellites as well as the growing interest in laser and quantum communication call for a cost-efficient solution for managing microvibrations. This paper describes how cheap MEMS-based measurement systems have already proven that they are a potential solution. Showing high sensitivity and low-noise performance while allowing fast and easy prototyping.

Micro-vibrations and wave propagation in biperiodic cylindrical shells

80%

Tomczyk B. , Litawska A.

tom Vol. 22, nr 3

789--807

The objects of consideration are thin linearly elastic Kirchhoff-Love-type circular cylindrical shells having a periodically microheterogeneous structure in circumferential and axial directions (biperiodic shells). The aim of this contribution is to study a certain long wave propagation problem related to micro-fluctuations of displacement field caused by a periodic structure of the shells. This micro-dynamic problem will be analysed in the framework of a certain mathematical averaged model derived by means of the combined modelling procedure. The combined modelling applied here includes two techniques: the asymptotic modelling procedure and a certain extended version of the known tolerance non-asymptotic modelling technique based on a new notion of weakly slowly-varying function. Both these procedures are conjugated with themselves under special conditions. Contrary to the starting exact shell equations with highly oscillating, non-continuous and periodic coefficients, governing equations of the averaged combined model have constant coefficients depending also on a cell size. It will be shown that the micro-periodic heterogeneity of the shells leads to exponential micro-vibrations and to exponential waves as well as to dispersion effects, which cannot be analysed in the framework of the asymptotic models commonly used for investigations of vibrations and wave propagation in the periodic structures.