Effective vibro-acoustical modelling of rubber isolators
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]
This thesis, gathering four papers, concerns the enhancement in understanding and modelling of the audible dynamic stiffness of vibration rubber isolators including experimental measurements.
Paper A studies the performances of three different types of vibration isolator using an indirect measurement technique to estimate the blocked dynamic transfer stiffness of each specimen. The measurements are performed over a wide audible frequency range of 200 to 1000 Hz in a specially designed test rig enabling the investigation of arbitrary preload influences.
Paper B addresses the modelling of the audible-frequency stiffness of the rubber conical mount experimentally appraised in Paper A accounting for preload effects. The model is based on a simpliflied waveguide approach approximating the nonlinearities attributed to the predeformations by adopting shape factor considerations. The carbon black filled rubber is assumed incompressible, displaying a viscoelastic behavior based on a fractional derivative Kelvin-Voigt model efficiently reducing the number of required material parameters.
In Paper C the focus is on the axial dynamic stiffness modelling of an arbitrary long rubber bushing within the audible frequency range. The problems of simultaneously satisfying the locally non-mixed boundary conditions at the radial and end surfaces are solved by adopting a waveguide approach, using the dispersion relation for axially symmetric waves in thick-walled infinite plates, while fulfilling the radial boundary conditions by mode-matching. The results obtained are successfully compared with simpliflied models but display discrepancies when increasing the diameter-to-length ratios since the influence of higher order modes and dispersion augments.
Paper D develops an effective waveguide model for a pre-compressed cylindrical vibration isolator within the audible frequency domain at arbitrary compressions. The original, mathematically arduous problem of simultaneously modelling the preload and frequency dependence is solved by applying a novel transformation of the pre-strained isolator into a globally equivalent homogeneous and isotropic configuration enabling the straightforward application of a waveguide model to satisfy the boundary conditions. The results obtained present good agreement with the non-linear finite element results for a wide frequency range of 20 to 2000 Hz at different preloads.
Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , p. 25
Series
Trita-AVE, ISSN 1651-7660 ; 2005:25
Keywords [en]
Applied mechanics, Rubber isolator, Bush mounting, Dynamic stiffness, Waveguide, Fractional derivatives, Mode-matching, Pre-compressed, Prestrain, Preload, Predeformation, Viscoelasticity, Dispersion
Keywords [sv]
Teknisk mekanik
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-266ISBN: 91-7178-104-8 (print)OAI: oai:DiVA.org:kth-266DiVA, id: diva2:8332
Public defence
2005-06-16, D3, Lindstedtsvägen 5, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101001
2005-06-072005-06-072022-06-23Bibliographically approved
List of papers