Multi-Visco-Elastic Contact Model in Discrete Element Method -Application to Margarine's Process Engineering

A new contact model, which is called 'multi-visco-elastic contact model', is developed in the Discrete Element Method (DEM) to represent rheological characteristics of fat spread and simulate the dynamics in a kneading machine for improving the uniformity and the efficiency of filling-up of fat spread. The new rheological contact model is connected with a Maxwell component and several Kelvin components in series. Using the new contact model, the overall bulk material composed of small-sized discrete elements shows a time-dependent rheological characteristics, since the model represents rheological characteristics at each contact point. Several simple simulations, which show stress relaxation and creep characteristics, are conducted to verify the new model. The results are in good agreement with analytical ones. Also creep simulations, which mimic lab-scale creep experiments, are conducted. The results are compared with the experimental ones. As a result, it is clarified that the multi-visco-elastic contact model represents rheological characteristics of fat spread well and the scheme enables one to simulate dynamics of fat spread during the process.