Abstract
This paper derives a modal expansion of structural intensity for longitudinal and bending vibration on beams. The expansion is expressed by the superposition of modal terms expressed by the product of weight coefficients and cross-modal functions. Cross-modal function is presented by the product of two modes with or without spatial derivatives. Numerical simulation is carried out in order to verify the modal expansion derived. The expansion is also applied to calculate the structural intensity on a beam with a branch in order to discuss the description by the cross-modal functions to change the intensity due to the branch attached.
