An isotropic viscoelastic phase field fracture model for flexural loading of freshwater columnar ice

Abstract

This work presents the development and implementation of a coupled isotropic phase field fracture and viscoelastic computational model to simulate the fracture of freshwater columnar ice undergoing flexural stresses. An existing incremental constitutive model is extended to capture ice behavior up to and just after material fracture occurs. Crack initiation and propagation is modeled through a Griffith’s energy-based phase field formulation that includes contributions from viscous energy dissipation. The variational formulation and implementation of the material model in the open-source platform Dolfinx is discussed. We present 3-point flexural bending experimental data of freshwater columnar ice grown in controlled conditions which are used to inform the model’s mechanical properties. We find that the coupled model captures the creep and fracture behavior of ice specimens well for strain rates on the order of 10−5s−1 at −10 °C. Finally we show that although our model includes viscoplastic effects, freshwater ice under these conditions develops little viscous energy and therefore instantaneous mechanisms dominate its fracture behavior.