Investigation on Parameter Identification and Coarse Graining Models using Discrete Element Capability in LS-DYNA

Processes such as transportation, flowing and processing of powder materials can be seen in the manufacturing process of various industrial products and are important processes for manufacturing high quality products. Discrete Element Method (DEM)[1] is widely used as a simulation method to handle powder materials, and excellent DEM function is also implemented in LS-DYNA. The DEM model can be used intuitively, and there is an advantage that stable computation can be performed. On the other hand, the DEM model is a hypothetical model based on the spring-mass model, and in order to reproduce the real phenomenon with high accuracy, it includes many numerical parameters that the user must decide beforehand. In this paper, the simulation of a compression experiment of polymer pellets were performed and the result of the parameter identification using optimization software LS-OPT is reported. In addition, when DEM is applied to fine powder material, the number of particles becomes enormous, and in many cases it cannot be processed in a common computational environment. In such a case, a coarse graining model is used to reduce the number of particles and computational load. Various ideas have been proposed for the method of coarse graining so far, and in this paper several coarse graining models were tested to compare powder behavior in drum mixing problem.