Loss and coupling loss factors of two coupled dynamic systems

Abstract

The statistical Energy Analysis (SEA) has been used to define and estimate the responses of complex dynamic systems. Often a complex dynamic system is modeled by dividing it into a number of subsystems—called basic dynamic systems. Within the format of SEA, the description of the model is given in terms of the loss and coupling loss factors. But to define the model, means must be devised for determining the values of these factors. This paper examines experimental methods that can be used to identify the factors. Considerations are limited to a complex consisting of two dynamic systems, but the elements for an extension to higher forms of complexes are included. The loss and coupling loss factors are formulated in terms of standard measured quantities obtained from experiments which involve quasi-transient as well as steady-state conditions. The formalism is used to ascertain the sensitivity and accuracy with which the factors can be estimated. It is demonstrated that not all the factors can usually be estimated with equal accuracy; indeed, a factor may escape determination altogether. The results may thus guide experimental schemes and procedures used in modeling complex dynamic systems in the format of SEA.