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Advances in Aircraft and Spacecraft Science Volume 3, Number 2, April 2016 , pages 197-209 DOI: https://doi.org/10.12989/aas.2016.3.2.197 |
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Beating phenomena in spacecraft sine testing and an attempt to include the sine sweep rate effect in the test-prediction |
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Pietro Nali and Alain Bettacchioli
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| Abstract | ||
| The Spacecraft (S/C) numerical sine test-predictions are usually performed through Finite Element Method (FEM) Frequency Response Analysis (FRA), that is the hypothesis of steady-state responses to harmonic excitation to the S/C base is made. In the test practice, the responses are transient and may be significantly different from those predicted through FRA. One of the most significant causes of discrepancy between prediction and test consists in the beating phenomena. After a brief overview of the topic, the typical causes of beating are described in the first part of the paper. Subsequently, focus is made on the sine sweep rate effect, which often leads to have beatings after the resonance of weakly damped modes. In this work, the approach illustrated in the literature for calculating the sine sweep rate effect in the case of Single-Degree-Of-Freedom (SDOF) oscillators is extended to Multi-Degrees-Of-Freedom (MDOF) systems, with the aim of increasing the accuracy of the numerical sine test-predictions. Assumptions and limitations of the proposed methodology are detailed along the paper. Several assessments with test results are discussed and commented. | ||
| Key Words | ||
| sine sweep rate effect; sine test-predictions; beating phenomena; sine testing; FRA | ||
| Address | ||
| Pietro Nali: Thales Alenia Space Italy, Strada antica di Collegno, 253 - 10146, Turin, Italy Alain Bettacchioli: Thales Alenia Space France, 5 Allée des Gabians - 06150 Cannes, France | ||
