Effective vibro-acoustical modelling of rubber isolators
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
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. , 25 p.
Trita-AVE, ISSN 1651-7660 ; 2005:25
Applied mechanics, Rubber isolator, Bush mounting, Dynamic stiffness, Waveguide, Fractional derivatives, Mode-matching, Pre-compressed, Prestrain, Preload, Predeformation, Viscoelasticity, Dispersion
IdentifiersURN: urn:nbn:se:kth:diva-266ISBN: 91-7178-104-8OAI: oai:DiVA.org:kth-266DiVA: diva2:8332
2005-06-16, D3, Lindstedtsvägen 5, Stockholm, 10:00
QC 201010012005-06-072005-06-072010-10-01Bibliographically approved
List of papers