Phase field model for the fracture of soft elastomers
Wei Hong (Iowa State University), Xiao Wang (Iowa State University)
Soft Materials and Structures
Tue 10:45 - 12:15
Barus-Holley 158
Phase-field models have been developed in the past decades for microstructure evolution and damage of solids. The phase-field modeling of fracture has mostly been limited to brittle and linear elasticity materials. In this research, the existing phase-field model for brittle fracture is extended and applied to soft elastomers that exhibit hyperelastic and even viscoelastic behaviors with finite deformation. Just as in a brittle fracture model, a scalar phase-field variable is used to represent the damage level of the material, and a gradient energy term is introduced to represent the fracture energy (surface energy). Assumed to be a function of the gradient with respect to the reference configuration, this fracture energy is the intrinsic fracture energy independent of deformation. In other words, it gives rise to surface energy, but not surface tension. Physically, this energy is associated with the rupture of polymer chains. The energy related to the localized inelastic deformation is captured by the continuum model of the surrounding material. This model reveals the crack shape and fracture process zone, and more importantly the rate dependency of the fracture toughness of soft elastomers. When the Zener model of a single characteristic relaxation time is assumed for the material, the total fracture energy is not a monotonic function of the loading rate - it reaches maximum at an intermediate strain rate with a crack speed comparable to the relaxation time.