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Ice Forces and Ship Response to Ice. Consolidated Report

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Final rept.

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Conclusions from this study include 1 Both peak force and peak pressures during an impact increase with ice severity ice thickness and ice strength. 2 In arctic regions, operation at higher latitudes increases ice severity and therefore ice loads. 3 Peak pressure during an impact appears to be only weakly dependent on impact speed, and no dependency was discernable from the measured data. 4 Peak force during an impact does increase with impact speed and a linear relationship between them appears reasonable. 5 Total force increases with increasing contact area but average pressure decreases with increasing contact area. 6 The average pressure distribution on the ship hull within the impact zone at an instant in time is asymptotic to a line of constant force at large areas and to a line proportional to a negative fractional power of area in the range of -0.2 to -0.3 at small areas, The latter asymptote appears related to the triaxial crushing strength versus strain rate dependency of the ice. 7 Extreme value distributions of ice force and pressure for the most severe ice conditions show Frechet type or upward curving distributions. Intermediate ice conditions follow a Gumbel or linear type distribution. Only the distributions for data recorded in light first-year ice conditions appear to be bounded or Weibul type distributions.

Subject Categories:

  • Snow, Ice and Permafrost
  • Marine Engineering

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