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Title of the thesis: Model Ice: Physical mechanisms of formation and mechanical properties

Thesis defender: Mohammad Izadi
Opponent: Prof.  Rocky Taylor, Memorial University of Newfoundland, Canada 
Custos: Prof. Jukka Tuhkuri, Aalto University School of Engineering

Model Ice: Physical mechanisms of formation and mechanical properties
Understanding how ice interacts with ships and offshore structures is essential as arctic activities increase. In his doctoral thesis, Mohammad Izadi investigates how to improve the accuracy of laboratory experiments used to design vessels and offshore platforms operating in icy waters.

The study focuses on “model ice,” a type of ice used in ice tanks to simulate real sea ice at a smaller scale. The purpose of the research was to understand the physical mechanisms behind model ice formation and to develop a new method that better replicates the mechanical behavior of natural sea ice. This research addresses a long-standing challenge in the field: existing model ice materials often fail to reproduce key properties of sea ice, such as stiffness and brittle failure behavior. As a result, experimental predictions for ice–structure interaction may not be very accurate. 

A key finding in the thesis is that, contrary to common assumptions, water droplets used in traditional spraying type model ice production do not freeze in air before reaching the surface of water or ice. This leads to wet and soft ice, different to sea ice. To overcome this challenge, the study introduces a novel method where droplets are nucleated using compressed air, enabling them to freeze earlier.

The new method produces very fine-grained model ice (VFG) with improved stiffness, strength, and fracture behavior, closely resembling those of natural sea ice. Importantly, the method uses fresh water and avoids chemical additives, making it more sustainable than the earlier model ice materials. The results can be directly applied in ice tank facilities to improve the reliability of model-scale experiments. This has practical implications for the design of Arctic ships, offshore wind turbines, and other marine structures, contributing to safer and more efficient operations in cold regions.

The study concludes that controlling droplet freezing and ice microstructure are critical for achieving realistic model ice. The proposed method provides a robust solution for future research and engineering applications. 

Thesis available for public display 7 days prior to the defence at . 

Contact information: mohammad.izadi@aalto.fi