Identification of Damping Characteristics of Viscoelastically Damped Structures Using Vibration Test Results

Abstract

Damping plays an important role in structural stability and vibration control and so frequently special efforts are taken to increase structural damping, of which the most effective measure to date is the viscoelastic damping treatment. However, damping properties, especially those of viscoelastic damping, are the most difficult to model analytically but can only be revealed by vibration test. This paper examines the feasibility of identifying damping characteristics of viscoelastically damped structures whose damping and stiffness characteristics are frequency dependent by correlating finite element modelling with vibration test results and presents an effective method for achieving such an objective. Measured frequency response function data are used instead of conventional modal data, since in the case of viscoelastically damped structures that are frequency dependent modal data are not defined while frequency response functions can be easily measured. The method is developed based on the practical assumption that the measured coordinates are incomplete and the identified damping matrix is physically meaningful and possesses the same physical connectivity as that of the stiffness matrix. Computational aspects regarding the practical application of the proposed method are discussed. Several numerical case studies are given to demonstrate the practical applicability of the proposed method.