The evaluation of vibratory power transmission in structural junctions is an important part of the study of structure-borne noise. In this paper, a method for calculating the transmission efficiency of three-dimensional beam junctions is described. It takes into account the effects of unsymmetrical bending, mode coupling between bending and torsional waves, as well as shear deformation and rotary inertia of beams. The beams are connected through a common attachment point which may not coincide with the shear centre or the beam centroid. Wave transmission theory is used in the analysis to formulate equations of the coupled bending and torsional motions and the complex wave amplitudes are solved by considering the boundary conditions at the junction. The complex wave amplitude are then used to evaluate the wave power and hence the transmission efficiency. Samples of calculations for some beam junctions are presented to illustrate the method. Results from a symmetrical T-junction show that the coupling between bending and torsional waves has a considerable effect on wave transmision at high frequencies. (C) 1995 Academic Press Limited. [References: 9]
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