In order to investigate ice forces on offshore structures, the impact of a semi-infinite moving ice bar is considered. Based on typical observations of ice-structure impact, a continuum damage mechanics approach for ice property descriptions is adopted for the theoretical simulation of the ice-structure interaction. The method of characteristics is applied to solve the wave propagation problem with the evolution of continuum damage. The numerical results, using representative published ice properties, show some interesting aspects of the initial stages of the ice-structure interaction process. The results serve as an initial attempt to put ice load predictions, including damage evolution on a solid theoretical basis.
Ice forces acting on marine structures in the arctic region have been a crucial interest to designers and researchers. Because 'of the various failure mechanisms of the ice, e.g., spalling, flexural cracking, splitting, and plastic flow, it is very difficult to simulate the breaking mechanism by a simple model of the ice. The actual forces generated when ice features impinge against a structure involve a complex interaction of various failure modes as penetration continues (Timco, 1989). A simplified theoretical model of the above-mentioned ice- structure impact scenario can be made possible when the continued damage mechanics approach is used for the constitutive modelling of ice. This allows for a description of microcraek damages in the medium. Jordann and McKenna (1989), and Choi (1989) reviewed the historical approach of the continuum damage mechanics and ita application to ice mechanics. A typical example of an ice-structure interaction is shown in Fig. 1. In Fig. I, the structure is considered as a rigid wall. A semi-infinite ice strip is moving toward the structure. In the following analysis, we further simplify this scenario by assuming a uniaxial state of stress within ice.