Penetration Fracture of Sea Ice Plate: Simplified Analysis and Size Effect

Abstract

Vertical penetration of an object through a floating elastic‐brittle plate from the bottom up or the top down is studied. Based on field observations, it is assumed that many symmetric cracks grow radially from a small loaded area, and the maximum load is achieved at the initiation of circumferential cracks. Nevel's approximation, in which the plate wedges between the radial cracks are analyzed as narrow floating beams of linearly varying width, is adopted. This makes an analytical solution possible. The rate of energy release due to the radial crack growth is calculated according to linear elastic fracture mechanics and the theory of thin plates. This yields the dependence of the radial crack length on the load, which is considered to be uniformly distributed along a small circle. It is confirmed that there is a size effect such that the nominal stress (load divided by ice thickness squared) that causes similar cracks to grow is proportional to (icethickness)-3/8 or, equivalently, to (flexuralwavelengths...