Evaluation of Three Ice-Structure Interaction Models

Ari Muhonen

Tekniikan lisensiaatintutkimus 1996.
Thesis for the Degree of Licentiate of Science in Technology.

Thesis in PDF format (ISBN 951-22-6335-1)   [4126 KB]

Abstract

This work concentrates on the contact between an ice edge and a vertical indenter face during intermittent crushing. The results of a laboratory indentation test series are analyzed and a description of the physical phenomena occurring at the contact is given. The existing dynamic ice-structure interaction models are reviewed. The ability of three models to simulate representative test results is evaluated.

The results of the indentation test series consist of 77 tests of which 23 are analyzed. The tests were carried out in a small basin with a floating sheet of columnar grained freshwater ice. The ice was horizontally loaded with an indenter which was installed in front of a spring-mass system. Special attention was paid to the visual observations in order to find the physical phenomena occurring at the ice deformation process.

The ice failure process was cyclic in the whole analyzed parameter space. The apparent crushing frequency was dependent on the indenter velocity and the lowest natural frequency of the structure. The latter also affected the peak force values: the higher the natural frequency the lower the force.

The ice failed in flaking. The flakes were formed locally by different size macrocracks which separated the flakes from the parent ice. This lead to a chain reaction which caused the deformation of the whole contact face during the load drop. The resulting ice wedge was crushed during the spring-back phase following the load drop.

The results of three representative tests were simulated using three different type dynamic ice-structure interaction models. None of the models performed well when the needed parameter values were obtained straight from the tests or the test conditions. However, when the parameter values were modified, the match improved considerably.

Keywords: ice-structure interactions, loading, dynamic loads, laboratory tests, freshwater ice, ice crushing, mathematical models, simulation, evaluation

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