Stability analysis and comparative experimentation for two substructuring schemes, with a pure time delay in the actuation system

Ryuta Enokida, David Stoten, Koichi Kajiwara

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

In recent years there has been a focus on two types of scheme for dynamical substructure testing: the hybrid scheme (HS) and the dynamically substructured system (DSS) scheme. Although these approaches are fundamentally different in the manner of compensation/control, the comparative performance of the schemes has not yet been studied in simulated or real experimental tests. This paper studies the performance of these schemes via tests on a simple base-isolated structure with a natural rubber bearing. In dynamical tests, a guarantee of stability for the experimental system is essential in order to achieve a safe and reliable result. Pure time delays can be present in such experimental systems, primarily due to discrete-time computational elements, which will promote instability. This paper studies the stability of HS and DSS test systems, with a prime focus on the effect of pure time delays. In particular the schemes were applied to the substructure testing of a rubber isolation bearing, where the overall system included a digital computation time delay of τ=6 ms resulting from a series of control, data acquisition and signal filter elements. Neither delay compensation nor adaptive/self-tuning methods were included in these tests, in order to establish a fair and objective comparison between the basic forms of the two schemes. It was found that DSS stability was preserved in the presence of the 6 ms delay, whereas HS was rendered unstable. This increase in robustness was due to a linear substructure controller (LSC) used in the DSS, which was based upon a knowledge of the dynamics of the transfer system and substructures. In addition, DSS exhibited significant robustness to further artificial increases in the pure time delay, eventually yielding to instability at a value of τ=17 ms. Analysis of the two schemes was found to be effective at predicting accurate stability conditions in advance of actual experimentation.

Original languageEnglish
Pages (from-to)1-16
Number of pages16
JournalJournal of Sound and Vibration
Volume346
Issue number1
DOIs
Publication statusPublished - 2015
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Acoustics and Ultrasonics
  • Mechanical Engineering

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