Ships in ice : the interaction process and principles of design

• Main Author: Zou, Bin
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1996
• Subjects: Ice Sheet
• Online Access: https://research.library.mun.ca/1328/; https://research.library.mun.ca/1328/1/Zou_Bin.pdf; https://research.library.mun.ca/1328/3/Zou_Bin.pdf

For ships operating in arctic and sub-arctic waters, ice load is a major threat. Due to the uncertainties in ice conditions and varying operating situations, an accurate estimation on design ice load is difficult. The objective of the present research is to investigate the ice loads and the associated structural strength from aspects of mechanics, statistics and design principles. -- First, the ice-structure interaction process is investigated from the view point of mechanics. The interaction is characterized by ice fracture and damage. The ice load is highly localized within high pressure regions termed critical zones. A numerical analysis was carried out to investigate how a crack may propagate in an ice sheet and how the ice material is damaged during an ice-structure interaction. The analysis showed that small shear cracks, with mixed modes, are more likely the candidates for the fracture spalls and the formation of critical zones. -- Critical zones vary in space and time. These critical zones are characterized using parameters such as spatial density, zonal area, and the zonal force. These parameters in the model were calibrated using ship trial data of CCGS Louis St. Laurent. The ice loads on a design area were modelled as a random number of critical zones, each with a random force. Based on this model and extreme value theory, a design curve was proposed for the estimation of extreme ice loads. -- Third, the strength of the structure was investigated. A long plate, loaded by uniform pressure was proposed as the design model for the plating. Due to the randomness of ice load, there are uncertainties associated with the design model. To understand this uncertainty, various load scenarios were investigated using the finite element method. The results show that the plate fails at a dominant section, which fails in a way similar to an "equivalent long plate". Factors affecting the failure of the panel are lateral support and interaction between critical zones. These factors were investigated and empirical ...