American crewed spaceflight systems have used a significant tracked transportation system to rollout the stacked vehicle and launch platform from the Vehicle Assembly Building (VAB) to the launch pad. This system has been shown to produce specific narrow-band harmonic forces that can excite the complete system, including the ability to force a resonance for long periods of time. This work reports on the efforts to develop tools and processes to reconstruct rollout forcing functions to support advanced needs for the extraction of dynamic properties. The multi-step processes provided in this work include a hybrid version of a traditional force reconstruction approach; transfer of expected CG forces to the assumed force input locations; expansion of the forces to a full-rank set of input forces; application of known dynamic constraints; and joint updating of FRFs and the estimated forces.
Three levels of success criteria are suggested for these processes as applied to analytical, laboratory, or measured field data: synthesizing output accelerometer data; reconstructing input forcing functions; and estimating modal properties. A dynamically simple system, limited instrumentation, and a simple single-speed forcing function are used to provide measured and analytical data to exercise and assess the tools of interest. Useful comparisons supporting the first success criteria are provided. Data and insight are also provided for the second success criteria. The simplicity of the example system supporting the work reported in this paper does not yet support the development of significant insight on the third success criteria. Follow-on activities are recommended to add additional insight into the process success with all three criteria.
This work not only addresses engineering development work of specific and unique interest to spaceflight systems but also suggests general applicability for force estimation, dynamic property estimation, and operational testing situations. Specifically these tools are to enable the estimation of dynamic properties when the loading and constraint environments complicate traditional OMA techniques. Unique contributions of this process include: expanding inputs and constraints of traditional force reconstruction techniques; using null space vectors to complete the basis set for full rank force reconstruction; and constraining linear solutions to filter estimated forces for targeted force updating.
Forcing Function Estimation for Space System Rollout
Conf.Proceedings of Society
Sensors and Instrumentation, Aircraft/Aerospace, Energy Harvesting & Dynamic Environments Testing, Volume 7 ; Kapitel : 24 ; 245-278
2020-09-30
34 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
Forcing Function Estimation for Space System Rollout
TIBKAT | 2021
|Tema Archiv | 1976
Online Contents | 1996