FREQUENCY-RESPONSE FUNCTIONS FOR STRUCTURAL INTENSITY .1. THEORY

The frequency response function for structural intensity is a ratio of intensity at a response point to input power at an excitation point. At a zero frequency value, this function represents a ratio of time-av eraged intensity at the receiving point to time-averaged power input a t the source point, and at all other frequencies the frequency respons e function represents a ratio of the amplitude of the fluctuating inte nsity at the receiving point to the amplitude of the fluctuating power at a source point. Thus, the frequency response function for structur al intensity reflects both vibration power transfer and fluctuation in a structure, and it allows one to calculate the intensity at a receiv ing point when the input power at the source point is known. The defin ition of frequency response function for structural intensity is propo sed in this paper. General theoretical formulas and a measurement meth od are developed to determine frequency response function for structur al intensity. A one-degree-of-freedom system, a uniform beam, and plat es are analyzed to demonstrate the properties of the frequency respons e function for use in structural intensity and calculation methods. So me potential uses of this frequency response function for structural i ntensity are presented.