Particle Models

Damage simulation in heterogeneous materials

Fig. 1 Mesoscale model of a sand-lime block – particle distribution in a cube with a side length of 12 cm (80,000 spheres)

Fig. 2 Mesoscale model of a sand-lime block – uniaxial compression test: macroscopic stress-strain curves.

Fig. 3 Mesoscale model of a sand-lime block – uniaxial compression test: particle displacements (final state).

Fig. 4 Mesoscale model of a sand-lime block – uniaxial compression test: damage (final state).

Fig. 5 Drilling simulation – schematic representation of the numerical model.

Fig. 6 Drilling simulation - approximation of the twist drill geometry by triangular surfaces.

Fig. 7 Drilling simulation – particle displacements after one second of drilling.

Fig. 8 Drilling simulation – damage after one second of drilling.

Fig. 9 Simulation of edge breakage – chisel shapes: rounded flat chisel, flat chisel, pointed chisel

Fig. 10 Simulation of edge breakage – particle displacements (t=12ms).

Fig. 11 Simulation of edge breakage – three-dimensional damage distribution (t=12 ms).

Fig. 12 Simulation of edge breakage – damage distribution (t=12 ms, section along the chisel axis).

 The nonlinear behavior of heterogeneous materials, such as in concrete products or sand-lime bricks, is characterized mainly by the formation of microcracks within the structure of the material. Hence, these materials are of a multiscale nature: the behavior of a structural component is determined by processes within the material structure. This phenomenon provides the opportunity of using numerical simulations for analyzing the behavior of the material on various length scales.

On the macroscale, the key dimensions of the structural component define the characteristic dimension of the model. Since these dimensions are usually considerably larger than the dimensions of the individual material components, macroscale models largely neglect the heterogeneous nature of the material. Rather, the material is assumed to be homogeneous and isotropic. In this approach, the corresponding properties of the material are characterized by effective parameters. These models capture nonlinear material behavior mainly by complex nonlinear material laws that provide only a...