Triaxial Testing of First-year Sea Ice

Triaxial Testing of First-year Sea Ice
Author: J. A. Richter-Menge
Publisher:
Total Pages: 60
Release: 1986
Genre: Ice mechanics
ISBN:

This report presents the first series of conventional triaxial tests carried out on columnar first year sea ice samples obtained from the field and tested under controlled laboratory conditions using a large-capacity test machine. A total of 110 horizontal ice samples from Prudhoe Bay, Alaska, were tested on a closed-loop electro-hydraulic test machine at -10 C in unconfined and confined constant-strain-rate compression. The confined tests were conducted in a conventional triaxial cell that maintained a constant ratio between the radial and axial stress to simulate in situ loading conditions. The load ratios used were 0.25, 0.50 and 0.75. The strain rate of each test was constant at 0.01, 0.001, or 0.00001/s. Data are presented on the strength, failure strain and initial tangent modulus of the first year sea ice under these loading conditions. The effects of confining pressure, strain rate and ice structure on the mechanical properties of the ice are examined.

Ice Loads and Ship Response to Ice. Summer 1982/Winter 1983 Test Program

Ice Loads and Ship Response to Ice. Summer 1982/Winter 1983 Test Program
Author: J. W. St John
Publisher:
Total Pages: 233
Release: 1984
Genre:
ISBN:

Work toward development of local ice load criteria for icebreaking ships is presented. A bow panel of approx. 100 sq ft was instrumented to measure ice pressures by measuring compressive strains in the webs of transverse frames. The panel was divided into 60 sub-panel areas, 6 rows of 10 frames, over which uniform pressures were calculated during an impact with ice. A digital data acquisition system recorded only events over a present threshold strain. A microprocessor controlling data acquisition allowed real time data to be streamed through memory such that the recorded data were the 60 channel strain time-history from 1 sec before to 4 sec after the threshold was exceeded, sampling each channel at 32 Hz. Approximately 1400 such events were recorded on two deployments, one to the Beaufort Sea in Sep-Oct 1982 recording summer multiyear ice impacts and one to the Chukchi Sea in Mar-Apr 1983 recording both first year and multiyear winter ice impacts. All strain data were converted to pressure time-histories over each of the 60 sub-panels. Finite element models of the hull structure were used to develop a data reduction matrix relating measured strains to uniform pressures. The result is a spatial and time representation of each impact. Extreme pressure area curves were developed for each event. Extreme envelopes of pressure vs. area were were developed from data for each of 5 areas; south and north Bering Sea, South and north Chukchi Sea, and Beaufort Sea. Trends in peak force and peak pressure are examined in terms of ship impact speed and ice conditions. (edc).

SSC.

SSC.
Author: United States. Ship Structure Committee
Publisher:
Total Pages: 344
Release: 1990
Genre: Naval research
ISBN:

Mechanics of Ice Failure

Mechanics of Ice Failure
Author: Ian Jordaan
Publisher: Cambridge University Press
Total Pages: 246
Release: 2023-02-28
Genre: Technology & Engineering
ISBN: 1108689728

Featuring real-world examples and practical methodology, this rigorous text explores time dependence in the mechanics of ice. Emphasizing use of full scale data, and implementing risk-based design methods, mechanical theory is combined with design and modelling. Readers will gain understanding of fundamental concepts and modern advances of ice mechanics and ice failure processes, analysis of field data, and use of probabilistic design methods, with applications to the interaction of ships and offshore structures with thick ice features or icebergs. The book highlights the use of viscoelastic theory, including nonlinearity with stress and the effects of microstructural change, in the mechanics of ice failure and fracture. The methods of design focus on risk analysis, with emphasis on rational limit-state principles and safety. Full discussion of historical discoveries and modern advances – including Hans Island, Molikpak, and others – support up-to-date methods and models to make this an ideal resource for designers and researchers.