Simulation of the Fletcher-Gent effect by using of the subroutine UPHI MSC/MARC©

In the presented work is demonstrated one of the possible ways to implement a rheological microplastic model (Rabkin et al. 2003) into the finite element MSC/MARC((c)), namely via the modified external user defined subroutine UPHI The original subroutine UPHI allows to simulate the small harmonic vibrations about a preloaded state in a hyperelastic solid. Since the vibrations are described on the basis of the theory of linear viscoelasticity, the amplitude dependence of the complex stiffness (Fletcher-Gent, or the Payne effect) cannot be taken into account. The techniques to FE-implementation of the Fletcher-Gent effect within the framework of the modified subroutine UPHI are described. The practical examples of the application of the modified subroutine for evaluation of the complex stiffness and the comparison between the theoretical predictions and the experimental results are given.