| Résumé | A key aspect of ice impacts on ship hulls and other structures is the shape of the impacted surface, particularly when there is plastic deformation due to the impact force/pressure and potential for increased confinement. To study this issue, some relatively simple ice-crushing tests have been performed in the lab using four different acrylic crushing platens: one that was flat, a second that had a shallow spherical-cap hollow, a third with a spherical-cap hollow with a greater radius of curvature, and a fourth with a cylindrical-cap hollow. The influences of the ‘degree of hollow’ and ‘shape of hollow’, i.e. the amount of confinement, were investigated by crushing identically-shaped granular freshwater ice specimens against the four platens, where the penetration rate was 16 mm/s and the ambient temperature was -10 °C. In addition to load/displacement measurements, high-speed imaging data of the platen-ice interface (to view hard-zone / soft-zone ice contact evolution during crushing) were acquired through the transparent acrylic platens. The shape and loading characteristics of the ice at the contact interface are discussed in the context of the four differing crushing-platen surface shapes. The average load data throughout the penetration range for the four crushing platens can be explained by three effects: the differing degrees of lateral confinement generated by the various platens; the flow and constriction behavior of the crushed ice (i.e. shattered-spall debris) generated by spallation events at the hard zones; the increasing bulk-ice confinement with penetration as the platens get closer to the ice-holder at the base of the ice samples. |
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