Vibration reduction in lightweight floor/ceiling systems with a sand-sawdust damping layer

This paper shows how to use a mathematical model to predict the vibration of lightweight timber-framed floor/ceiling systems (LTFSs) caused by mechanical excitation. The LTFS considered here is made up of an upper floor layer, a cavity space with timber joists and a ceiling. These components are joined by timber battens, ceiling furring channels and ceiling clips. The vibration in the structure is caused by a localized excitation on the top surface and the resulting vibration level of the ceiling surface will be analysed. The cavity space is filled with fibre infill for damping the sound transmitting through the cavity. A unique feature of the design and the model is the sand-sawdust mixture in the upper layer. The theoretical model and the experimental measurements show that the sand-sawdust dampens the vibration in the frequency range between 10 and 200 Hz. The damping by the sand-sawdust and the fibre infill are found by comparing the numerical simulations against the experimental measurements. We show that the simple linear frequency dependent loss factors can be used to predict the low-frequency vibrations of LTFSs.

[1]  Annett Wechsler.  Structure Borne Sound Structural Vibrations And Sound Radiation At Audio Frequencies 3rd Edition , 2016 .

[2]  Damping and elastic properties of binary powder mixtures , 2002 .

[3]  Meei-Ling Lin,et al.  The effects of frequency on damping properties of sand , 1996 .

[4]  Brian R. Mace,et al.  Sound radiation from a plate reinforced by two sets of parallel stiffeners , 1980 .

[5]  Clive L. Dym,et al.  Energy and Finite Element Methods In Structural Mechanics : SI Units , 2017 .

[6]  E. J. Richards,et al.  On the prediction of impact noise, VII: The structural damping of machinery , 1984 .

[7]  L. Cremer,et al.  Structure-Borne Sound: Structural Vibrations and Sound Radiation at Audio Frequencies , 1973 .

[8]  Warren E. Blazier,et al.  Investigation of low‐frequency footfall noise in wood‐frame, multifamily building construction , 1994 .

[9]  Hyuck Chung,et al.  Fourier Series Solutions to the Vibration of Rectangular Lightweight Floor/Ceiling Structures , 2008 .

[10]  George Dodd,et al.  Forest and Wood Products Australia Project PN04.2005: maximising impact sound resistance of timber framed floor/ceiling systems , 2007 .

[11]  Colin H. Hansen,et al.  ENGINEERING NOISE CONTROL: Theory and Practice , 1988 .

[12]  F. Fahy,et al.  Sound and Structural Vibration: Radiation, Transmission and Response , 1987 .

[13]  J. Allard.  Propagation of Sound in Porous Media: Modelling Sound Absorbing Materials , 1994 .

[14]  J. C. Sun,et al.  Predictions of total loss factors of structures, part II: Loss factors of sand-filled structure , 1986 .

[15]  Brian R. Mace,et al.  Periodically stiffened fluid-loaded plates, II: Response to line and point forces , 1980 .

[16]  Jonas Brunskog.  Acoustic excitation and transmission of lightweight structures , 2002 .