Finite element models with viscoelastic damping

A useful method of modelling viscoelastic effects in structures for transient response analysis is to treat the frequency dependence of the usual damping model through the introduction of extra dissipation co-ordinates or internal variables. These new co-ordinates require a curve fit to the material loss factor data over a range of frequencies. These methods have the disadvantage of introducing a large number of extra degrees of freedom that make response calculations and controller design very computationally intensive. This paper examines methods to reduce the model size and hence ease this burden. Eigensystem truncation and balanced realisations are used to reduce the full model. An iterative method to calculate the full eigensystem is introduced, using the frequency dependent material modulus.