Rational Fraction Polynomial Method and Random Decrement Technique for Force-Excited Acceleration Responses

Abstract

This paper addresses a parameter identification problem of a linear dynamic system resulting from forced acceleration responses when input forces are unknown. The problem is attributed to an input force imposed on its impulse acceleration response function. An identification procedure is provided as a solution to reduce the error caused by the identification problem. The procedure applies the mode indicator function, the complex mode indication function, and the rational fraction polynomial method to identify the modal parameters of the dynamic system from the frequency response functions of the random decrement signatures. Applicability of this procedure is investigated through numerical simulations of a three degree-of-freedom dynamic system loaded by Gaussian white and color noise forces. For the purpose of comparison, the autoregressive model is also used to analyze the same example. Results show that the proposed procedure can improve the identification accuracy of the modal parameters from the acceleration-based random decrement signatures, when comparing with the use of the autoregressive model.