Estimation of ship bow-iceberg impact forces with consideration of the sliding effect

Abstract

A simplified method to estimate the impact force in ship bow-iceberg collisions is presented. The eccentricities of both iceberg and ship are included. The friction at the contact point is also included so that the sliding effect is taken into account. The impact force is determined by a concept of energy consideration including both on normal and tangential directions during the collision. This method consists of three steps. First, a full 3D model is applied to assess the energy dissipation in a ship bowiceberg collision based on impulse momentum and energy conservation. Second, the force- and energy dissipation-indentation relationships are determined by the pressure-area relationship and the contact areaindentation relationship. Third, the impact forces are derived by using the calculated dissipated energy and the force/energy-indentation relationship from the previous two steps. This method was applied in the case studies to investigate the effects of the iceberg shapes, the normal frame angle of the ship, the friction coefficient and the ice pressure-area relationship on the impact force. The impact forces for various iceberg masses obtained by the present method were compared with the design loads calculated according to IACS’s rule for Polar Ships. The differences were analyzed and discussed in this paper.