ABSTRACT
Several researchers have presented successful methods to model the effects of viscoelastic damping mechanisms which introduce hysterisis. An effective approach is to introduce additional co-ordinates to account for the frequency dependent and hysteretic behaviour. Motivated by the need to produce finite element models that are capable of predicting the dynamic response of a structure or component, Hughes and his co-workers (Golla and Hughes, 1985, McTavish and Hughes, 1993) and Lesieutre and his co-workers (1990, 1992, 1995, 1996) developed independent means of augmenting an finite element model with new co-ordinates containing damping properties found from material loss factor curves. The Golla-Hughes-McTavish (GHM) method uses a
second order physical co-ordinate system and the Lesieutre approach uses a first order state space method called the Augmenting Thermodynamic Fields (ATF) method. Both are superior to the Modal Strain Energy method proposed by Rogers et al (1981). While the MSE method is substantially easier to use, both the ATF and the GHM methods are more accurate. These two more complex approaches are able to account for damping effects over a range of frequencies, complex mode behaviour, transient responses and both time and frequency domain modelling. Inman (1989) applied the GHM approach to simple beams and Banks and Inman (1991) provided an alternate time domain method for modelling hysterisis.
