Effect of Elastic Boundary Supports and Stiffening Treatments on Vibroacoustic Response of Plate-like Structures.

摘要

In this thesis, the vibroacoustic responses of unstiffened and stiffened, thin plates with arbitrary elastic boundary supports were investigated. Both the steady-state and the transient vibroacoustic behaviors of the plate were studied. The aim was to examine the effects of the elastic boundary supports and the stiffeners on the vibroacoustic performance in order to provide guidance to the design and installation of plate-like structures for sound insulation.;A method was first developed to determine the actual boundary condition of the plate system; this was based on a coupled finite element and boundary element method (FEM/BEM) in frequency domain. This model was then improved and applied to predict the steady-state vibration and sound radiation (SVSR) of a stiffened plate; this allowed for an efficient computation of a plate with arbitrary boundary conditions and with arbitrarily located stiffeners.;Another method was proposed to predict the transient vibration and sound radiation (TVSR) of a plate with arbitrary elastic boundary supports, which was based on the time-domain finite element method (TDFEM) and time-domain boundary element method (TDBEM). This model was then improved and applied to predict the TVSR of a stiffened plate.;Extensive experiments were carried out in two connected semi-anechoic chambers at The Hong Kong Polytechnic University; these included the STL measurements of unstiffened and stiffened plate structures and the transient sound radiation measurements of unstiffened and stiffened plate structures. The proposed boundary condition identification method was used to identify the actual boundary conditions of the plate structures used in the experiments. The predicted results agreed well with measured data.;Both the results of the experiments and the parametric studies clearly demonstrated that the sound insulation (or vibration isolation) performance of plate structures can be improved through an appropriate use of the elastic boundary supports or stiffeners or both. The proposed prediction models can be effective design tools for this purpose.