Numerical Modelling of Brittle Failure in Ice Structures

Abstract

The main purpose of this Master's thesis is to use finite element method to investigate if brittle failure in sea ice can be described in a force-displacement history. Four implemented material models in LS-Dyna are taken into account. This in order to study the behaviour by an interaction between drifting sea ice and offshore structures. The force-displacement curve give a sawtooth pattern by brittle failure. Four material models were studied, characterised and used in three different numerical models. The material models are referred as 063_Mat_Crushable_Foam, 096_Mat_Brittle_Damage, 111_Mat_Johnson_Holmquist_Concrete and 153_Mat_Damage_3 in the keyword user's manual for LS-Dyna. The numerical results were compared with each other and with measured values from real experiments. The comparisons were performed with a vertical force-displacement history. All material models had results in the right order of magnitude.From the results, it can be concluded that it seems possible to find an existing material model that can give sufficient results for interaction between ice and structures. It will be preferable to use material models with an included damage constant.