A CONSTITUTIVE CREEP MODEL FOR SINGLE-CRYSTAL ICE

A constitutive creep model for single crystal ice has been formulated based on the experimental results and the mechanism of the multiplicat ion process of mobile dislocations. In this model, the primary mechani sm is considered to be the dislocation motion on the basal planes of s ingle crystal ice due to strong creep anisotropy. The preferred crysta llographic orientation and temperature of single crystal ice are incor porated in describing both the elastic and the inelastic deformations in the creep model. Material properties used in the model are the disl ocation velocity and the changing dislocation density of single crysta l ice based on experimental data. The proposed uniaxial creep model is extended to a biaxial model by allowing inelastic deformation only al ong the basal planes. Parametric studies are performed to better under stand the dependence of macroscopic stress-strain curves on microstruc tural parameters. The results show strong influence of the loading rat e and stress level. Comparison of the model predictions with experimen tal data shows excellent agreement over a range of strain rates.