This paper on "Simulations with Non-Linear Constitutive Models of Materials" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Summary

Paper describes four problems taken from design work on modem centrifugal separators, in which simulation of non-linear phenomena has been utilized. The first example concerns the elastic-plastic deformation of the separator bowl which occurs during overspeed test runs needed for stabilizing the material prior to normal operation of the separator. FEA results are compared with measurements. It is concluded that simulation gives adequate precision but material characterization is crucial. The second example describes non-linearity due to slip motion between parts, simulated by means of gap elements in FEA. The third example is taken from nonlinear viscoelasticity, where a hereditary integral formulation is used for describing deformation of polymer parts. Prediction of long-term behaviour by means of results from high-speed tensile tests can be made. Finally, as the fourth example, simulation of the behaviour of an electro-rheological fluid for damping purposes is illustrated. Simulation of non-linear phenomena is advantageous in design work but should not be expected to yield as precise results as conventional linear modeling. This is often due to limited experimental verification of the models used.