Structure-borne sound transmission from machines in buildings, part 2: Indirect measurement of force and moment at the machine-receiver interface of a single point connected system by a reciprocal method

There is increasing evidence that moments are significant contributors in m achine induced structure-borne sound. Omission of these components in predi ction can therefore lead to an underestimate of total power in some cases, although it is recognised that considering all transmission paths in predic tion generally is not a practical approach, due to the complex nature of th e problem. A way forward is to establish the installation conditions and th e primary transmission paths and components in order that the-least importa nt can be neglected for simplification in the prediction. To permit the mea surement of force and moment at machine contacts, the indirect method descr ibed in a companion paper (Part 1) was employed. Experimental results for a machine attached to a concrete floor and a brick wall demonstrate that the contribution of moment components is sensitive to source location. At low frequencies, moments are less important than vertical forces when the sourc e is away from the structural discontinuities such as floor edges. However, moments are important at low frequencies when sources are in the proximity of structural discontinuities. Moments have an increasing contribution wit h increased frequency irrespective of excitation location. (C) 1999 Academi c Press.