Determination of granular assemblies' discrete element material parameters by modelling the standard shear test

Soil and agricultural products interact with the tools and equipment used to manipulate and storethem. This interaction causes the load of the tools and of the agricultural product. The practicing engineerhas to know how these types of materials behave so as to be able to examine and control their mechanicalbehaviour. To fulfil this aim we have to find a general model of these materials and apply this to the specificcases. A relatively new model of granular assemblies is the so called discrete element based model. In thismodel we describe the granular assembly as the collection of large number of small rigid bodies, and themodelling process of the assemblies’ behaviour is based on solving the equations of motion of this largenumber of particles directly. The question that arises from the practical use is how we can determine theparameters which affect the interaction between the particles: the coefficient of static- and rolling friction,coefficient of restitution, Young modulus and Poisson’s ratio of a given (in some cases very small) particle.The direct measurement of these quantities is of course impossible for really small particles. We developeda new method based on performing the standard shear test of the given materials and by modelling theshear test using discrete element method. If the discrete element parameters of the numerical model areproperly set, the output data coming from the measurement will be in good agreement with the data comingfrom the discrete element model.