UCREEPNETWORK

The input files consist of one element each with the material response specified using the parallel rheological framework with two or three viscous networks. The Bergstrom-Boyce creep model is defined in network one and network three (for the model with three viscous networks) using user subroutine UCREEPNETWORK. A two-step analysis is performed. The specimen is preloaded in the first static step in which viscous effects are not active. In the second, quasi-static, step the viscous effects are activated and a constant load is maintained throughout the step, so the material is subjected to creep. The results were compared to the results obtained with an equivalent model that uses the built-in Abaqus Bergstrom-Boyce model.