Direct Identification of Damping Parameters From FRF and Its Application to Compressor Engineering

A technique to identifY damping parameters directly from the frequency response functions (FRF) in matrix forms has been developed. Furtl1ermore, the technique identifies the viscous damping and structural damping coefficients separately. The technique provides more accurate damping values because it does not rely on the information of the natural modes as in the conventional method. The damping effect is identified as two matrices, which represent the viscous damping and the internal damping effects. Therefore, the best use of the technique is considered to build a hybrid finite element method (FEM) modeL For example, the mass and stiffness matrices of a hermetic compressor can be formulated from the FEM program, while the damping matrices, which should include fue effects of tlle internal components such as lubrication oil, are identified by fue proposed mefuod. Such a hybrid model will be able to predict the characteristics of complicated systems as a hermetic compressor much more accurately.