Transient creep of polycrystalline ice under uniaxial compression: an assessment of internal state variable models

Abstract

Th e efforts to d evelop d a mage models for ice canno t be disco nnec ted fr om a better kn owl edge of th e und a maged ice behaviour. In this respec t th e transient behaviour of polyc rys ta llin e ice still need s to be in ves tiga ted. The prese nt pa per is a co ntributi o n to th e d evelo pm ent of rh eological mod els whi ch can be used in varying load situ a ti o ns. Th e d eform a tion processes whi ch should be the fo und a tion of th e models are d escribed . Th e mod els of Le G ac a nd Du va l ( 1980) and of Sunder and Wu ( 1989 a ) a re tes ted aga inst two uni ax ia l co mpression tes ts on isotropi c g ra nular ice und er varying load . Th ey fa il to describe bo th prim a ry creep a nd th e res ponse to increm ents/d ecrements of th e a ppli ed load . A new mod el, based on a d eco mposition of th e visco pl a ti c stra in into two compon ent whi ch account se pa ra tel y fo r kin em a ti c a nd isotropi c ha rd ening, is shown to give better res ults.