ABSTRACT
For a material or structural model, which satisfies the extended Masing rules under cyclic loading, a unique parallel or series Iwan-model exists which characterises the stress-strain response. Both the parallel and series version of the model result in the same stress-strain response when loaded in one dimension. In numerical implementation, the series approach is particularly suited for a stress controlled algorithm since the same stress applies to each of the spring-slider elements. For the parallel approach, the same strain applies to each of the spring-slider elements, making it suitable for a strain controlled algorithm. The hyperplasticity approach provides a rigorous framework to extend both the series and parallel version to higher dimensions and derive the incremental response. Though both models can be calibrated to simulate the same response in 1D, the extensions to 2D illustrate that there is a small difference between the stress-strain behaviour of these models in higher dimensions. This paper illustrates the similarities and differences between the behaviour of the series and parallel Iwan-models.
