@article{MeckingScheibengraberKruseetal.2017, author = {Mecking, Simon and Scheibengraber, Markus and Kruse, Tobias and Schanda, Ulrich and Wellisch, Ulrich}, title = {Experimentally based statistical analysis of the vibrational energy of CLT building elements}, series = {24th International Congress on Sound and Vibration, ICSV24, London, United Kingdom, July 2017}, journal = {24th International Congress on Sound and Vibration, ICSV24, London, United Kingdom, July 2017}, year = {2017}, abstract = {The method is based on a simplified Statistical Energy Analysis(SEA) approach. The energy ratios of various subsystems are the main quantities to predict sound transmission. The method has proven to work sufficiently accurate for masonry and concrete buildings, where the building components like walls, floors etc. can be regarded as rather homogeneous structures. To adapt this method for solid timber constructions it is necessary to prove that basic SEA requirements are fullfilled by orthotropic materials and heterogeneous structures that occur in these building types. In a case study, an isolated T-junction formed by Cross Laminated Timber(CLT) elements is experimentally investigated. The buildings elements are subdivided in segments with typical screwed connections. In the experiments the diffusivity of the vibration field is investigated, using point excitation with a shaker at several positions and many, randomly chosen response positions. MONTE-CARLO simulations are conducted for random but fix-sized subsets of the measured response positions to find the necessary number of response positions for an accurate determination of the vibrational energy. As a result the distribution of the mean velocity levels can be approximated. In a second approach a multiple linear regression model based on the least absolute shrinkage and selection operator(LASSO)is applied, because for lower frequency bands multicollinearity is expected. In the context of linear regression modelling, data-driven methods are used to select optimal subsets of response positions, to get an estimating equation.}, language = {en} } @inproceedings{MahnHopkinsSchandaetal.2013, author = {Mahn, J. and Hopkins, C. and Schanda, Ulrich and Krajci, L.}, title = {Competitive wooden floor systems - multi-objective optimization based on acoustics improvement}, series = {Internoise 2013}, booktitle = {Internoise 2013}, year = {2013}, abstract = {The objective of this research project is the design of lightweight timber floor systems which have similar thicknesses to those of concrete floors but which perform better than concrete in terms of their environmental life cycle impact and in terms of airborne and impact sound insulation. The availability of superior lightweight acoustic designs will increase the share of timber based floors within the Swiss construction market and will contribute to higher wood utilization in general. A program for systematically developing validated finite element models for the development of lightweight timber floor systems has been proposed. The use of Swiss hardwoods in floor systems will be studied and implemented where possible. Keywords: lightweight timber, sound transmission, impact noise}, language = {en} } @inproceedings{SchoepferHopkinsMayretal.2014, author = {Sch{\"o}pfer, Fabian and Hopkins, Carl and Mayr, Andreas R. and Schanda, Ulrich}, title = {Case study on the vibrational behavior of a timber-frame structure}, series = {European Acoustics Association (EAA) (ed.), Forum Acusticum, Krakow, Poland, 2014.}, booktitle = {European Acoustics Association (EAA) (ed.), Forum Acusticum, Krakow, Poland, 2014.}, year = {2014}, language = {en} } @article{SchoepferHopkinsMayretal.2017, author = {Sch{\"o}pfer, Fabian and Hopkins, Carl and Mayr, Andreas R. and Schanda, Ulrich}, title = {Measurement of transmission functions in lightweight buildings for the prediction of structure-borne sound transmission from machinery}, series = {Acta Acustica united with Acustica}, volume = {2017}, journal = {Acta Acustica united with Acustica}, number = {103}, pages = {451 -- 464}, year = {2017}, language = {en} } @article{SchoepferHopkinsMayretal.2017, author = {Sch{\"o}pfer, F. and Hopkins, C. and Mayr, A. and Schanda, Ulrich}, title = {Prediction of noise from machinery in timber-frame buildings using transmission functions}, series = {Proceedings of ICSV24}, journal = {Proceedings of ICSV24}, year = {2017}, abstract = {To ensure that building regulations are satisfied, the sound pressure level due to machinery has to be predicted at the design stage of a new building. With the increasing popularity of multistory timber dwellings, prediction becomes an important issue for designers and consultants. At present previous project experience is often used when considering the design of wall and floor constructions and the mounting positions for machinery. Simple tools to calculate the sound pressure levels in rooms based on machinery data and construction details are not currently available. The approach involves two stages: firstly the description of the source and secondly the prediction of vibration transmission across the building and sound radiation into the rooms. In this paper a simple empirical model is proposed for the second stage. This approach is based on measured transmission functions that are defined as the average sound pressure level in a receiving room relative to the injected structure-borne sound power. This is a logical extension of approaches to characterize structure-borne sound sources that also use a power based descriptor (e.g. prEN15657:2016-02: Acoustic properties of building elements and of buildings - Laboratory measurement of structure-borne sound from building service equipment for all installation conditions) and provides a simple method to estimate the sound pressure level in a room.}, language = {en} } @article{HopkinsFilippoupolitisFerreiraetal.2016, author = {Hopkins, C. and Filippoupolitis, M and Ferreira, N. and V{\"o}ltl, R. and Schanda, Ulrich and Mahn, J. and Krajci, L.}, title = {Vibroacoustic finite element modelling of the low-frequency performance of a solid timber floor formed from dowel-connected joists}, series = {Proceedings of Inter-Noise 2016}, journal = {Proceedings of Inter-Noise 2016}, year = {2016}, abstract = {This paper investigates the prediction of low-frequency impact sound insulation for a solid timber floor formed from dowel-connected joists with Swiss hardwood. A finite element model was developed for the dynamic response of the floor as it is neither homogeneous nor isotropic and has complex connections. With point force excitation, a FEM model for the dynamic response of the floor was validated using experimental modal analysis in the laboratory. Two different FEM models were developed, one using spring connectors and the other using join connectors. Good agreement between FEM and measurements in terms of the Modal Assurance Criterion (MAC) and eigenfrequencies was achieved for the first 14 modes with the spring connector model and for the first 7 modes with the join connector model. However, for the vibroacoustic analysis it was necessary to use the join connector model due to the computational instabilities of the spring model above 100 Hz when it was coupled to the acoustic medium. With mechanical excitation the radiated sound power from the underside of the timber floor was measured with sound intensity in order to calculate the radiation efficiency. Comparison of measurements and FEM showed reasonable agreement between 20Hz and 200Hz}, language = {en} } @inproceedings{VoeltlFranzenSchanda2009, author = {V{\"o}ltl, R. and Franzen, T. and Schanda, Ulrich}, title = {Experimental investigations on the sound transmission of drywall constructions at low frequencies}, series = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (ed.), DAGA}, booktitle = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (ed.), DAGA}, year = {2009}, language = {en} } @inproceedings{BuchschmidKohrmannWinteretal.2013, author = {Buchschmid, M. and Kohrmann, M. and Winter, C. and M{\"u}ller, G. and V{\"o}ltl, R. and Schanda, Ulrich}, title = {Vibroacoustic Characteristics of Light-Weighted Slabs. Part 2: Measurement-Based Investigation of the Sound Radiation of Suspended Ceilings}, series = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (ed.), Fortschritte der Akustik - DAGA}, booktitle = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (ed.), Fortschritte der Akustik - DAGA}, year = {2013}, abstract = {In this contribution a method for the prediction of the radiated sound out of the velocity field of a vibrating ceiling is presented. The numerical method was validated via measurements on a real structure using a pp-probe. It is based on Integral Transform techniques and can be applied in the postprocessing of a FEM simulation (harmonic analysis) [1]. The method was verified by measurements on the real structure and can be used for parametrical studies. Rounding off the Parts 1 and 2 of this publication nomograms, based on dimensionless parameters, can be developed to predict the sound radiation of light weight slabs. Hereby different sets of geometry as well as different configurations of ceilings can be studied in order to describe the acoustical and dynamical behaviour of wooden ceilings.}, language = {en} } @inproceedings{KohrmannBuchschmidGreimetal.2013, author = {Kohrmann, M. and Buchschmid, M. and Greim, A. and M{\"u}ller, G. and Schanda, Ulrich}, title = {Vibroacoustic Characteristics of lightweighted Slabs. Part 1: Aspects of Numerical Modeling, Model Updating and Parametric Studies using the Buckingham π -Theorem}, series = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (ed.), AIA-DAGA}, booktitle = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (ed.), AIA-DAGA}, year = {2013}, abstract = {In order to set up guidelines for the design of light-weighted ceilings for timber constructions to be used by engineers in practice, investigations based on both measurements and numerical models have been carried out [1, 2, 3]. 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 in order to enable computations with varying geometry and material parameters and calibrated with the help of 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, which fulfil the radiation condition, can be selected and the pressure field in the adjacent acoustic fluid can be computed. Due to the properties of the Fourier-Transform the radiated sound power can be calculated efficiently in the transformed domain out of pressure and velocity. In a second part of the contribution 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 individual nodes at the interface}, language = {en} } @inproceedings{KohrmannBuchschmidMuelleretal.2013, author = {Kohrmann, M. and Buchschmid, M. and M{\"u}ller, G. and V{\"o}ltl, R. and Schanda, Ulrich}, title = {Numerical models for the prediction of vibroacoustical characteristics of light-weighted ceilings}, series = {Internoise 2013}, booktitle = {Internoise 2013}, year = {2013}, abstract = {In order to set up guidelines for the design of light-weighted ceilings for timber constructions to be used by engineers in practice, investigations based on both measurements and numerical models have been carried out within the cooperative research project "VibWood". In this contribution the setup and the calibration of the numerical model of the structure as well as the prediction of radiated sound are discussed, where a special focus is set on a dimensionless description in order to deduce information for a wide range of system's specifications. 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 (e.g.support conditions, contact phenomena dynamic properties of individual parts) are considered. The model is parameterized in order to enable computations with varying geometry and material parameters. After calibrating the FE-model with the help of measurements using model updating techniques dimensionless parameters are defined based on the Buckingham-π- Theorem and computations are carried out in order to specify guidelines for various systems. The radiation of sound is computed in a post processing using Integral Transform Methods.}, language = {en} }