Use of Statistical Energy Analysis for Rotating Machinery, Part I: Determination of Dissipation and Coupling Loss Factors Using Energy Ratios

Abstract

A method for determining the dissipation and coupling loss factors of a fully assembled machinery structure is presented in this paper. The method is based on the experimental measurements of the total loss factors and the energy ratios between the subsystems of the machine structure when fully assembled. The presented approach, which will be referred to as the energy ratio method, is suitable for both conservative (no energy dissipation at the junction) and non-conservative coupling. Not only does this energy ratio method determine the coupling loss factors for directly coupled subsystems, but it also determines the coupling loss factors between subsystems which are not directly coupled. This type of coupling exists when the subsystems of the structure are small compared to the wavelength of vibration and all coupling interfaces are in the near field of each other. A series of experiments are carried out to demonstrate the use of this approach and to verify the accuracy of this method for predicting the energy distribution among a set of coupled subsystems. The determined coupling and dissipation loss factors are used in a Statistical Energy Analysis (SEA) model of a rotating machinery component and the estimated results for the response are compared to the directly measured results. As expected, the agreement between the SEA estimated results and the directly measured results is good.