Abstract
This paper derives the modal descriptions of structural intensity for flexural vibration on plates. The modal expansion of the intensity is superposistioned by modal terms expressed by the product of weight function and the product of two modes with or without spatial derivative, which is called "cross-modal function" in this paper. It is also demonstrated that the expansion can design the excitation position for realizing the vortex energy flow on the plate, which flow type affects the radiation efficiency strongly. It is also shown that the products of two natural modes have the relation with the cross-mode functions, which enables to predict roughly the cross-mode functions when it is difficult to evaluate the spatial derivatives of natural mode.
