ESTIMATION OF VIBRATIONAL POWER IN BUILT-UP SYSTEMS INVOLVING BOX-LIKE STRUCTURES, PART 1: UNIFORM FORCE DISTRIBUTION

For the vibration analysis of built-up structures traditional point-like connections cannot be applied where the interface is large and the wavelength is small. In these situations the spatially distributed wavefield has to be accounted for, whereby the field properties associated with the interface (i.e., velocity, force) have to be considered to be continuous over a surface or, for a one-dimensional contact, along a line. Due to the perceived complexity of these distributions it is most common for analyses to employ a numerical technique which, whilst efficient as a methodology, is limited in that little is revealed about the physics of the system. The solutions can therefore be rather esoteric and in conjunction with design this makes the techniques cumbersome to use. As a move towards overcoming the problem the work presented considers a simplified analytical approach from which a model of a box-like structure is obtained. The basis of the approach is to consider the spatial properties of distributed forces in terms of their Fourier components and then hypothesize that the zero order, i.e., the uniform component, is dominant. In this way, the true spatial characteristics of the forces are retained but in a reduced and elementary form. This greatly simplifies the modelling. For the box-like structure, supported by an infinite plate-like recipient, a prediction of the vibratory power is considered and qualifying results established.