Particle model for quasibrittle fracture and application to sea ice

Fracture of quasibrittle materials with a large zone of distributed cracking is simulated by the particle model (discrete element method). The particles at the microlevel interact only by central forces with a prescribed force-displacement or stress-strain relation, which exhibits postpeak softening and is characterized by microstrength and microfracture energy. It is shown that a regular lattice, even though capable of closely approximating isotropic elastic properties, exhibits strong directional bias favoring propagation along a few preferred directions. A randomly generated particle model has no such bias. With a proper choice of the microlevel constitutive law, it can realistically simulate fracture of an ice floe during impact on a rigid obstacle. Explicit integration of the equations of motion is used to simulate the impact process and to explore the effect of the floe size and its initial velocity on the failure pattern and the history of the contact force.