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A lower bound analytical estimation of the fundamental lateral frequency down-shift of items subjected to sine testing

  • Received : 2019.07.26
  • Accepted : 2019.10.31
  • Published : 2020.01.25
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Abstract

The dynamic coupling between shaker and test-article has been investigated by recent research through the so called Virtual Shaker Testing (VST) approach. Basically a VST model includes the mathematical models of the test-item, of the shaker body, of the seismic mass and the facility vibration control algorithm. The subsequent coupled dynamic simulation even if more complex than the classical hard-mounted sine test-prediction, is a closer representation of the reality and is expected to be more accurate. One of the most remarkable benefits of VST is the accurate quantification of the frequency down-shift (with respect to the hard-mounted value), typically affecting the first lateral resonance of heavy test-items, like medium or large size Spacecraft (S/Cs), once mounted on the shaker. In this work, starting from previous successful VST experiences, the parameters having impact on the frequency shift are identified and discussed one by one. A simplified analytical system is thus defined to propose an efficient and effective way of calculating the lower bound frequency shift through a simple equation. Such equation can be useful to correct the S/C lateral natural frequency measured during the test, in order to remove the contribution attributable to the shaker in use. The so-corrected frequency value becomes relevant when verifying the compliance of the S/C w.r.t. the frequency requirement from the Launcher Authority. Moreover, it allows to perform a consistent post-test correlation of the first lateral natural frequency of S/C FE model.

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References

  1. Allen, M.S., Gindlin, H.M. and Mayes, R.L (2011), "Experimental modal substructuring to extract fixed-base modes from a substructure attached to a flexible fixture", Struct. Dyn., 3, 1085-1099. https://doi.org/10.1007/978-1-4419-9834-7_96.
  2. Apolloni, M. and Cozzani, A. (2007), "Virtual testing simulation tool for the new quad head expander electrodynamic shaker", Proceedings of the 6th International Symposium on Environmental Testing for Space Programmes, ESA-ESTEC, Noordwijk, The Netherlands, June.
  3. ESA-ESTEC (2013), Space Engineering, Spacecraft Mechanical Loads Analysis Handbook, European Cooperation for Space Standardization, ECSS-E-HB-32-26A, Noordwijk, The Netherlands.
  4. Lollock, J.A. (2002), "The effect of a swept sinusoidal excitation on the response of a single-degree-of-freedom oscillator", Proceedings of the 43rd AIAA Structures, Structural Dynamics and Materials Conference, Denver, Colorado, March. https://doi.org/10.2514/6.2002-1230.
  5. Mayes, R.L (2012), "Refinements on estimating fixed base modes on a slip table", Topics Modal Anal., I, 5, 359-365. https://doi.org/10.1007/978-1-4614-2425-3_32.
  6. Mayes, R.L., Schoenherr, T.F., Blecke, J. and Rohe, D.P. (2014), "Efficient method of measuring effective mass of a system", Topics Exper. Dyn. Substruct., 2, 311-320. https://doi.org/10.1007/978-1-4614-6540-9_25.
  7. Nali, P. and Bettacchioli, A. (2016), "Beating phenomena in spacecraft sine tests and an attempt to include the sine sweep rate effect in the test-prediction", Adv. Aircraft Spacecraft Sci., 3(2), 197-209. https://doi.org/10.12989/aas.2016.3.2.197.
  8. Nali, P. and Bettacchioli, A. (2017), "Virtual shaker testing: Un proceed de simulation tres prometteur", Essais et Modelisation, 131, 19-20.
  9. Nali, P., Appolloni, M. and Cozzani, A. (2018), Special Issue on Sine Testing Issues and the Virtual Shaker approach, Adv. Aircraft Spacecraft Sci., 5(2).
  10. Nali, P., Calvi, A., Casagrande, C., Caccamo, L., Di Pietro, V., Ladisa, P., Bitetti, G. and Lumaca, F. (2018b), "From virtual shaker testing to a handy analytical formulation for calculating the frequency down-shift of the S/C main lateral mode", Proceedings of the Aerospace Testing Seminar 2018, Los Angeles, California, U.S.A., October.
  11. Nali, P., Di Pietro, V., Ladisa, P., Bitetti, G., Lumaca, F. and Bettacchioli, A. (2018a), "Virtual shaker testing: Actual achievement in TAS and future prospects", Proceedings of the European Conference on Spacecraft Structures, Materials & Environmental Testing (ECSSMET 2018), ESA/ESTEC, Noordwijk, The Netherlands, June.
  12. Remedia, M., Aglietti, G., Appolloni, M., Cozzani, A. and Kiley, A. (2017), "An enhanced methodology for spacecraft correlation activity using virtual testing tools", J. Sound Vib., 409, 2017, 180-200. https://doi.org/10.1016/j.jsv.2017.07.054.
  13. Ricci, S., Peeters, B., Debille, J., Britte, L. and Faignet, E. (2008), "Virtual shaker testing: A novel approach for improving vibration test performance", Proceedings of the ISMA 2008 International Conference on Noise and Vibration Engineering, Leuven, Belgium, September.
  14. Ricci, S., Peeters, B., Fetter, R., Boland, D. and Debille, J. (2009), "Virtual shaker testing for predicting and improving vibration test performance", Proceedings of the 27th International Modal Analysis Conference (IMAC 2009), Orlando, Florida, U.S.A., February.
  15. Roy, N. and Girard, A. (2012), "Revisiting the effect of sine sweep rate on modal identification", Proceedings of the European Conference on Spacecraft Structures, Materials and Environmental Testing (ECSSMET 2012), Noordwijk, The Netherlands, March.
  16. Roy, N., Violin, M. and Cavro, E. (2018), "Sine sweep effect on specimen modal parameters characterization", Adv. Aircraft Spacecraft Sci., 5(2), 187-204. https://doi.org/10.12989/aas.2018.5.2.187.
  17. Waimer, S., Manzato, S., Peeters, B. and Wagner, M. (2016), "A multiphysical modelling approach for virtual shaker testing correlated with experimental test results", Special Topics Struct. Dyn., 6, 87-99, https://doi.org/10.1007/978-3-319-29910-5_9.
  18. Waimer, S., Manzato, S., Peeters, B., Wagner, M. and Guillaume, P. (2015a), "Experimental system identification of an electrodynamic shaker for virtual shaker testing", Proceedings of the ICEDyn, International Conference on Structural Engineering Dynamics, Lagos, Portugal, June.
  19. Waimer, S., Manzato, S., Peeters, B., Wagner, M. and Guillaume, P. (2015b), "Derivation and Implementation of an electrodynamic shaker model for virtual shaker testing based on experimental data", Proceedings of the 29th Aerospace Testing Seminar, Los Angeles, California, U.S.A., October.
  20. Waimer, S., Manzato, S., Peeters, B., Wagner, M. and Guillaume, P. (2018), "Experimental and analytical approaches in a virtual shaker testing simulation environment for numerical prediction of a spacecraft vibration test", Sensors Instrument. Aircraft Aerosp. Energy Harvest., 8, 71-81. https://doi.org/10.1007/978-3-319-74642-5_9.