@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} } @article{FilippoupolitisHopkinsVoeltletal.2017, author = {Filippoupolitis, M. and Hopkins, C. and V{\"o}ltl, R. and Schanda, Ulrich and Mahn, J. and KrajĨi, L.}, title = {Structural dynamics of a dowelled-joist timber floor in the low-frequency range modelled using finite element simulation}, series = {Engineering Structures}, volume = {148}, journal = {Engineering Structures}, pages = {602 -- 620}, year = {2017}, abstract = {This paper concerns the development and validation of Finite Element Methods (FEM) to simulate the dynamic response of a dowelled-joist timber floor. This is a solid floor comprised of timber joists connected using timber dowels with individual assemblies connected using inclined metal screws. The focus is on the structural dynamics in the low-frequency range up to 200 Hz which is the relevant range for impact sound insulation and vibration serviceability. Dowel connections between the joists that formed each assembly were modelled using either rigid or spring connectors in the FEM models. The validation against experimental modal analysis showed that both approaches were valid in terms of the eigenfrequencies, Modal Assurance Criterion (MAC) and the spatial-average velocity with point excitation. Whilst the FEM model with spring connectors had a higher number of correlated modes in the MAC analysis, this required removal of many spurious modes before predicting the response. The validated models were used to demonstrate the potential in predicting assessment parameters for vibration serviceability that are contained in EN 1995-1-1 (Eurocode 5). This predictive approach to the evaluation of vibration serviceability has the advantage in that it can be used for non-standard timber floors with non-standard boundary conditions or floor plans.}, 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} }