SENSITIVITY ANALYSIS FOR ESTIMATION OF COMPLEX MODULUS OF VISCOELASTIC MATERIALS BY NONRESONANCE METHOD

Abstract

One of the most influential factors of the complex modulus of a viscoelastic material is the frequency of excitation. Various techniques are available for the estimation of such characteristics, each of which has, of course, its own advantages as well as disadvantages. A non-resonance (dynamic stiffness) method is usually used to obtain the complex modulus over a wide range of frequency including resonance points in a relatively short time. However, the complex modulus obtained by this method often makes the estimations in the anti-resonance frequency regions unreliable because of the measurement noise problems. In this study, the effects of the measurement errors on estimating the complex modulus by two non-resonance methods, transmissiblility and impedance, for the case of longitudinal vibration of a rod-type specimen are investigated in respect to the sensitivity to measurement noise, and then in respect to obtaining a reliable frequency region for given error bounds. The results presented are supported by experimental results in the case of the transmissibility approach.