The mechanical properties of thick brash ice are considered, with special emphasis on the friction angle phi for a linear Mohr-Coulomb failure criterion. The static equilibrium of a uniform brash layer is discussed, and the internal stresses are given for neutral, active, and passive stress states. Horizontal displacement of brash by a smooth vertical plate is analyzed, and the crushing forces for plastic yielding in the passive stress state are deduced for cohesionless brash and for ice that has finite internal cohesion. ... In the analysis of low speed ship resistance, the emphasis is on resistance at the bow. Starting from analysis of penetration by a slender smooth wedge and taking accouht of interface friction in an approximate way, an expression is obtained for the resistance of "sharp" conventional bows, and comparisons are made with plasticity results for plane-strain penetration of wedges into semi-infinite media. ... The limiting ice resistance for ship movement can be related to the ship's thrust, which in turn can be estimated from readily available data such as shaft power and thrust per unit power. Equating the theoretical expression for ship resistance to a suitable expression for limiting propeller thrust at an appropriate hull speed, an estimate of limiting ice thickness is obtained. ... (Author)

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    Radarweg 29
    Amsterdam,   Netherlands  1043 NX
  • Authors:
    • Mellor, M
  • Publication Date: 1980-8

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  • Accession Number: 00324307
  • Record Type: Publication
  • Source Agency: Arctic Science and Technology Information System
  • Files: TRIS
  • Created Date: Feb 6 1981 12:00AM