Vibroacoustic Investigations of Light-Weight Ceilings - Modeling Aspects and Design Guidelines
Regular paper
Chair of Structural Mechanics - Technische Universität München
Wednesday 3 june, 2015, 14:00 - 14:20
Auditorium 2 (592)
Abstract:
In order to set up guidelines for the design of light-weighted ceilings for
timber-constructions, investigations based on both measurements and
numerical models have been carried out in the research-project "VibWood" at
TU München and HAW Rosenheim.
The setup and the calibration of the numerical model of the structure are
outlined briefly.
A semi-analytical approach for the prediction of radiated sound is
presented, which is based on Integral Transform Methods. The method can be
applied in the post-processing of a Finite-Element-computation. Thus as a
first step the structure, consisting of a timber-slab, a floating-floor and
a suspended ceiling, is built up in a Finite-Element-model, where the
material properties of wood and the characteristics of the system are
considered. The model is parameterized to enable computations with varying
geometry and material parameters and calibrated with measurements using
model-updating-techniques.
The velocity pattern resulting out of the FEM-computation is transformed
from the spatial into the wavenumber-domain and from the time into the
frequency-domain using Fourier-Transform-Methods. Applying this velocity
pattern as a boundary condition to the Helmholtz-Equation, which results out
of the Fourier-Transform of the wave equation the wavenumbers responsible
for sound radiation are selected and the pressure field in the adjacent
acoustic fluid is computed. In the Fourier-domain the radiated sound power
can be calculated efficiently out of pressure and velocity.
Then the model for the air-cushion in the suspended ceiling is discussed,
where a FSI-model for the acoustic fluid and the structure is compared
against engineering approaches using simplifications concerning mass
distribution and transfer-impedances between the interface-nodes.
Finally design-guidelines for light-weighted ceilings, set up in the
research-project, are presented in terms of a database containing
dimensionless results for different types of ceilings as well as a graphical
user interface to provide a user-friendly software environment.