TY - CHAP A1 - Mayr, Andreas R. A1 - Gibbs, Barry A1 - Fischer, Heinz Martin T1 - On force- and moment mobilities of a timber joist floor T2 - 35th German Annual Conference on Acoustics (DAGA), Rotterdam, March 2009. N2 - In wood framed buildings, floors are formed by fastening wood sheathing to joists spaced at a regular interval. The sheathing is typically fastened to the joist using screws so the resulting system is a complicated periodic point-connected plate-rib structure. It is shown that the point force mobility varies significantly with position. A machine installation generally is close to discontinuities, such as at: floor edges, joist-screw locations, joints between the sheathing plates, and due to workmanship. In such cases, moment excitation might become important at some frequencies and the neglect of moments a priori can ead to inaccurate prediction of the total emission. This paper presents measured point moment mobilities with respect to the distance to discontinuities for a timber joist floor where a single layer of chipboard forms the sheathing. It is shownthat the measured point moment mobility indicates an infinite plate behaviour. This includes for positions above a joist but between screw positions. To determine the relative contribution of moments and perpendicular forces to the total structure-borne sound power, case studies of two sources, a fan unit and a whirlpool bath, are described, for various locations on a timber joist floor. KW - Force- and moment mobilities KW - Timber joist floor Y1 - 2009 ER - TY - JOUR A1 - Mayr, Andreas R. A1 - Gibbs, Barry T1 - Point and transfer mobility of point-connected ribbed plates JF - Journal of Sound and Vibration N2 - The work reported in this paper addresses the problem of structure-borne sound transmission between vibrating sources and ribbed-plate receiver structures. Vibrating sources, such as pumps, motors, fans, etc., transmit vibro-acoustic power, causing noise complaints by occupants in cars, trains, aircraft, buildings and/or material fatigue and damage. The transmission process is complicated in that sources transmit power through several contacts and by up to six components of excitation at each contact. The structure-borne sound power is a function of source activity, source mobility and receiver mobility, and all three quantities must be known to some degree. For non-homogeneous receiver structures, such as thin-plate cavity constructions or lightweight framed constructions, the sheathing plates are typically fastened to the framing members using bolts, screws or spot-welded joints. Hence the resulting system is a point-connected ribbed plate structure and the receiver mobility is expected to vary significantly with position. Since measured receiver data seldom is available for prediction purposes, a method of estimating the point and transfer mobility of point connected ribbed plates is required. In this paper, an approximate approach, based on substitution forces, is described. The model uses infinite beam and infinite plate behaviour as input quantities. Estimates of point and transfer mobility are compared with measured results using a timber joist floor construction as an example. KW - Point and transfer mobility KW - point-connected ribbed plates Y1 - 2011 IS - 330 (2011) SP - 4798 EP - 4812 ER - TY - CHAP A1 - Gibbs, Barry A1 - Mayr, Andreas R. T1 - Estimates of mobility for prediction of structure-borne sound transmission in buildings T2 - 19th International Congress on Sound and Vibration, ICSV19, Vilnius, Lithuania, July 2012. N2 - This paper aims to provide a practical approach to the prediction of structure-borne sound power of mechanical installations in buildings. For structure-borne power, two source quantities, activity and mobility, are required, in combination with one receiver quantity, the receiver mobility. The source activity, in the form of free velocity or blocked force, is usually measured. For source mobility and receiver mobility, estimates, based on simple expressions, can provide a useful starting point. Also, machine bases may be categorised as: compact, plate-like, flanged or framed. Receiver structures, floors and walls, may be categorised as: plate-like, ribbed plate or framed plate. The estimates of source mobility are based on the rigid body value, the characteristic plate mobility and the fundamental plate frequency. For ribbed and framed plate structures, the mobility will vary with location, but again simple estimates of mobility, based on characteristic values and distance from the ribs, are possible. KW - Structure-born sound transmission KW - Estimates of mobility Y1 - 2012 ER - TY - JOUR A1 - Mayr, Andreas R. A1 - Gibbs, Barry T1 - Single equivalent approximation for multiple contact structure-borne sound sources in buildings JF - Acta Acoustica unitet with Acoustica N2 - The work reported in the paper addresses structure-borne sound transmission between multiple contact sources and non homogeneous plate receiver structures. This study concentrates on a practical method of predicting the installed structure-borne sound power from mechanical installations in lightweight buildings. The structure-borne sound power is a function of source activity, source mobility and receiver mobility, and all three quantities must be known to some degree. It is rarely practical to consider all transmission paths individually and in detail, and therefore, reduced data sets and less computationally demanding procedures are proposed. The paper examines how source data can be used to assemble single equivalent values, using spatial averages and magnitudes. Single equivalent values of receiver mobility also are proposed for lightweight, point-connected ribbed plate constructions. In case studies, the single equivalent values are used for predicting the structure-borne power in the installed condition. KW - Single Equivalent Approximation KW - Contact Structure-Borne Sound Sources in Buildings KW - Sound transmission Y1 - 2012 IS - 98 (2012) SP - 402 EP - 410 ER - TY - CHAP A1 - Gibbs, Barry M. A1 - Mayr, Andreas R. T1 - Source quantities for vibro-acoustic transmission into lightweight building elements T2 - Proceedings of Inter-Noise 2016 KW - Körperschall KW - HolzLeichtBau KW - Körperschallquellen KW - Transmission KW - Installationen Y1 - 2016 SN - 978-3-939296-11-9 ER -