The mechanical behavior of model-scale ice: experiments, numerical modeling and scalability

• Published in: Cold Regions Science and Technology
• Main Author: von Bock und Polach, Rüdiger
• Other Authors: Insinööritieteiden korkeakoulu, School of Engineering, Sovelletun mekaniikan laitos, Department of Applied Mechanics, Kujala, Pentti, Prof., Aalto University, Finland, Ehlers, Sören, Prof., Norwegian University of Science and Technology, Norway, Aalto-yliopisto, Aalto University
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Aalto University 2016
• Subjects: Marine engineering; model ice; numerical model; plasticity; bending strength; scaling; Arctic; Ice Sheet; Sea ice
• Online Access: https://aaltodoc.aalto.fi/handle/123456789/20380

Increasing levels of transportation and exploratory activities in the High North increase the significance of ice-capable ship designs, and the demand for them. This demand covers a wide range of ship types; such as tugs, vessels for search and rescue (SAR), patrol boats, military vessels, cruise ships, and merchant ships. Both the economically driven preference for operations in the Arctic over operations in a warmer climate, and the safety of the operations, require adequate performance prediction methods. The capability of model-scale ice and its availability and advantages in handling compared to sea ice spurred to the decision to investigate its material behavior to develop a numerical model. This model serves as a corner-stone towards a numerical ice tank and provides insight into the mechanical behavior of model-scale ice. Therefore, systematic ice property tests were conducted with the model-scale ice of Aalto University to define the material behavior. The model-scale ice is fine grained (FG) and doped with ethanol to artificially weaken the material. The experiments investigate the behavior until failure in tension, compression and bending. Furthermore, the elastic modulus is determined by ice sheet deflection experiments and the grain-size is measured. The stress plane that is investigated is orthogonal to the vertical (thickness) coordinate and is the same as the one in which stresses occur when ships interact with ice. On the basis of the experiments, the mechanics and the constitution of the model-scale ice are investigated to define a suitable material model and its parameters. It was found that a damage based elasto-plastic material model represents the behavior of the Aalto model-scale ice well. The numerical model accounts explicitly for flaws in the model-scale ice, comprised of voids filled with liquid and air, which are randomly distributed. It is found that the random distribution of flaws enables the reproduction of the variation in experimentally observed failure patterns and affects the response ...