Jordi Poblet-Puig

The role of studs in the sound transmission of double walls

Steel studs are used in double walls to provide structural stability. This creates a vibration transmission path between leaves that can often be more critical than the airborne path through the cavity. Some of the existing models for sound transmission consider the studs as elastic springs. The spring stiff ness may be taken as the cross-section elastic stiff ness of the stud, but this leads to an underestimation of the vibration transmission. A procedure to obtain more accurate parameters to be used in vibration and sound insulation models is presented. The results show that they must be obtained from dynamic models and/or experiments.

THE FINITE STRIP METHOD FOR ACOUSTIC AND VIBROACOUSTIC PROBLEMS

The finite strip method, widely employed in structural mechanics, is extended to solve acoustic and vibroacoustic problems. The acoustic part of the formulation, including how to handle the most typical acoustic boundary conditions and the fluid structure interaction, is presented. Several realistic problems where the three-dimensional domain of interest has extrusion symmetry are solved. These examples illustrate the advantages of the method: it has smaller computational costs than the finite element method and consequently the analyzed frequency range can be increased.

The block gauss-seidel method in sound transmission problems

Sound transmission through partitions can be modeled as an acoustic fluid–elastic structure interaction problem. The block Gauss–Seidel iterative method is used in order to solve the finite element linear system of equations. The blocks are defined, respecting the fluid and structural domains. The convergence criterion is analyzed and interpreted in physical terms by means of simple one-dimensional problems. This analysis highlights the negative influence on the convergence of a strong degree of coupling between the acoustic domains and the structure. A selective coupling strategy has been developed and applied to problems with strong coupling (e.g. double walls).

A boundary algebraic formulation for plane strain elastodynamic scattering

Solving of elastodynamic problems arises in many scientific fields such as wave propagation in the ground, nondestructive testing, vibration design of buildings, or vibroacoustics in general. An in...

A New Numerical Method for Solving the Acoustic Radiation Problem

A numerical method of solving the problem of acoustic wave radiation in the presence of a rigid scatterer is described. It combines the finite element method and the boundary algebraic equation one. In the proposed method, the exterior domain around the scatterer is discretized, so that there appear an infinite domain with regular discretization and a relatively small layer with irregular mesh. For the infinite regular mesh, the boundary algebraic equation method is used with spurious resonance suppression according to Burton and Miller. In the thin layer with irregular mesh, the finite element method is used. The proposed method is characterized by simple implementation, fair accuracy, and absence of spurious resonances.

A formulation for elastodynamic scattering based on boundary algebraic equations

The solution of the elastodynamic problem arises in many scientific fields such as the wave propagation in the ground, non-destructive testing, the vibration design of buildings or vibroacoustics in general. We present here an integral formulation based on the boundary algebraic equations. It leads to a boundary numerical method and has the important advantage that no contour (2D) or surface (3D) integrals need to be computed. This is very helpful in order to use combined field integral equations (numerical damping of fictitious eigenfrequencies) without the problems caused by the evaluation of hypersingular integrals. The key aspects are: (i) the approach deals with discrete equations from the very beginning; (ii) discrete (instead of continuous) tensor Green’s functions are considered (the methodology to evaluate them is shown); (iii) the boundary must be described by means of a regular square grid. In order to overcome the drawback of this third condition the boundary integral is coupled, if needed, wi...

Prediction of vibration reduction index for junctions made of cross laminated timber elements

The new revision of standard EN 12354-1 will provide some prediction formulas for estimating the vibration reduction index (Kij) of junctions made of cross laminated timber (CLT) elements. These are based on laboratory and in situ measurements. At the same time, new Kij prediction formulas for heavyweight junctions have also been added to this revised standard, in order to include large amount of data generated by means of parametric numerical analysis. The goal of this research is to study if the same philosophy based on numerical models used for the heavyweight junctions can be extended to CLT elements junctions. This step is not direct because the modeling of CLT structures implies a list of non-trivial aspects to take into account: (1) the details of the junction construction (i.e., direction and type of screws, presence of steel angles and plates); (2) the orthotropy on the mechanical properties of CLT panels; and (3) the different range of material properties and how damping must be considered in th...

Catalogue of vibration reduction index formulas for heavy junctions based on numerical simulations

© (2017) S. Hirzel Verlag/European Acoustics Association. The definitive publisher-authenticated version is available online at http://www.ingentaconnect.com/contentone/dav/aaua/2017/00000103/00000004/art00011 and http//dx.doi.org/10.3813/AAA.919091. Readers must contact the publisher for reprint or permission to use the material in any form.