Network modelling of fracture processes in fibre-reinforced quasi-brittle materials

Fracture processes in fibre-reinforced quasi-brittle materials were studied with a threedimensional structural network approach. The geometry of the meso-structure was modelled as polydispersed ellipsoids and line segments. Here, ellipsoids and line segments represented aggregates and fibres, respectively. The position of the aggregates was mapped on an irregular network of structural elements. With the network elements, the responses of aggregates, matrix and interfacial transition zones between aggregates and matrix were modelled. Fibres were modelled as beam elements, which were positioned independently of the background network. They were connected to the nodes of the background network via link elements. The influence of aggregates and fibres on fracture processes in direct tensile tests of periodic cells was investigated. In particular, the response in the form of stress-displacement curves, dissipated energy and roughness of fracture patterns was studied. It was shown that already small volumes of fibres of low aspect ratio (typical for steel fibres) strongly increased energy dissipation. However, these small volumes of fibres had a small effect on strength and roughness.