A study is presented of the theoretical response of ice subjected to constant velocity impact. The ice medium is idealized as a bar of fine grained polycrystalline ice which is confined in one direction perpendicular to the impact axis. A three dimensional continuum damage model is used to define the constitutive response of the ice. The physical model consists of a finite length bar and the impact problem is formulated by prescribing the boundary conditions of zero velocity at one end and a constant velocity at the other end. A finite difference scheme is employed to solve the governing system of differential equations. Comparisons are made for conditions of uniaxial stress, biaxial stress and plane strain. The contact stresses and the evolution of damage are found to be highly dependent on the degree of lateral confinement. It is also found that higher velocities lead to more highly concentrated damage zones.
Ice loadings pose serious threat to structures and floating vessels in ice covered waters. Uncertainties in ice load predictions can result in unnecessary construction delays, higher costs, and increased risks. Three aspects of concern are the global ice forces exerted on the entire structure, the local ice loads which are described in terms of distributed pressures and contact areas, and the dynamic interaction between the ice and structures. The existing technology for predicting local and global ice forces is far from satisfactory although much progress is being made (see for example Jordaan et a1. 1991). The difficulties in establishing appropriate ice forces for structural design is due to the complexities and uncertainties in describing:
the mechanical behavior of ice,
the characteristics of the ice features which may be encountered, and
the nonlinear coupling between the ice and the interacting structures.