We construct a constitutive relation for viscoelastic solid using a well-proven thermodynamical framework (see Rajagopal and Srinivasa [1]). The partitioned rate-type constitutive relation is implemented in Abaqus/Explicit using a user-defined Fortran subroutine, VUMAT. The implementation is verified using semi-inverse solutions of homogeneous and inhomogeneous deformations and is seen to match within a tight tolerance of 0.02%. It is shown that the three-parameter rate-type constitutive relation can emulate the mechanical response of a large class of filled elastomeric materials under small to moderate levels of strain (about 100%), which makes it well suited for designing viscoelastic dampers. The material parameters are obtained for natural and synthetic rubber-based dampers using data for double-shear for many frequencies and strain amplitudes.
Reference:
[1] K. R. Rajagopal, A. R. Srinivasa, A thermodynamic framework for rate type fluid models, Journal of Non-Newtonian Fluid Mechanics 88 (2000) 207–227.