Damage simulation of brittle heterogeneous materials at the grain size level

Microstructure models at the grain size level open new potentials for the numerical investigation of micromechanical damage and fracturing. This paper presents a strategy to model heterogeneous brittle structures composed of binder and aggregate using the Discrete Element Method (DEM). A discretisation concept for both components was developed and implemented using spherical particles as discrete elements. The aggregate grains were modelled by clusters of these particles. Special routines were developed to generate specimens, to simulate laboratory tests and to analyse these simulations. Methods were developed to calibrate homogeneous and heterogeneous material by the determination of appropriate constitutive laws and their corresponding parameters. The simulation strategy allows to distinguish in detail between inter- and intra-granular microfracturing, between shear- and tensile-cracking and between microcracks within or between the different components of the heterogeneous material. Exemplarily, selected simulation results are presented for MgO-concrete.