• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.788-799
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• 2014

This study conducted four field measurements of local ice pressure during the icebreaking voyage of the icebreaking research vessel "ARAON" in the Chukchi and Beaufort seas from July to August of 2010. For measurements, 14 strain gauges, including 8 strain gauge rosettes, were set on the bow of the port side. Influence coefficients were determined using a finite element model of the instrumented area and they were used to convert the measured strains on the hull structure to local ice pressures. The converted maximum pressure was calculated as 2.12 MPa on an area of $0.28m^2$. Pressure-area curves were developed from the surveyed pressure data and the results were compared with previously measured data. The study results are expected to provide an understanding of local ice pressures and thus be useful in the structural design of ice class ships.

• 한국해양공학회지
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• 제28권1호
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• pp.28-33
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• 2014

The Korean icebreaking research vessel "Araon" performed four sea trials in the Arctic and Antarctic Seas. The ice properties, such as the ice thickness, floe size, ice strength, and power of the vessel were quite different in these trials. To compare the speeds of ship with the same ice strength and power, the AARC (Arker Arctic Research Center) method is used with a vessel power of 10 MW and an ice strength of 630 Pa in this paper. Based on the analysis results, the speed of the ship was 1.62 knots (0.83 m/s) with a 1.02-m ice thickness and 2.5-km floe size, 5.3 knots (2.73 m/s) with a 1.2-m ice thickness and 1.0-km floe size, and 13.8 knots (7.10 m/s) with a 1.1-m ice thickness and 200-m floe size. The analysis results showed that the ship speed and floe size have an inversely proportional relationship. Two reasonable reasons are given in this paper for the final result. One is an ice breaking phenomenon, and the other is the effect of the ice floe mass. For the breaking phenomenon, the ice breaking force is very small because the ice floe is not breaking but tearing when a ship is passing through a small ice floe. Regarding the effect of the ice floe mass, it is impossible for a ship to push and tear an ice floe if the mass of the ice floe is too large compared to the mass of the ship. The velocity of the ship decreases when the ice floe has a large mass and a large size because the ship has to break the ice floe to move forward.

• 한국해양공학회지
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• 제28권5호
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• pp.423-428
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• 2014

Ice loads may be conveniently categorized as local ice loads and global ice loads. Local ice loads are often defined as ice pressures acting on local areas of shell plates and stiffeners. Therefore, local ice loads are defined in all ice class rules. However, directly measuring the local ice pressure using the actual ice class vessel is a very difficult task because appropriate instruments for direct measurement must be installed on the outer hull, and they are easily damaged by direct ice contacts/impacts. This paper focuses on the estimation of the local ice pressure using the data obtained from icebreaking tests in the Arctic sea in 2010 using the Korean icebreaking research vessel (IBRV) ARAON. When she contacted the sea ice, the local deformation of the side shell was measured by the strain gauges attached to the inside of the shell. Simultaneously, the contact area between the side shell and sea ice is investigated by analyzing the distribution of the measured strain data. Finally, the ice pressures for different contact areas are estimated by performing a structural analysis.

• 대한조선학회논문집
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• 제58권5호
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• pp.330-338
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• 2021

This paper focuses on the improvement of the influence coefficient matrix method for estimation of local ice load on the icebreaking research vessel ARAON. The influence coefficient matrix relates ice pressure on the hull plate to the measured/calculated hull strain/stress. Conventionally von Mises equivalent stresses representing hull stresses and ice pressure acting on the hull plate are utilized to assemble the influence coefficient matrix. Because of the three dimensional features of the ship-ice collision process, an enhanced method to assemble the influence coefficient matrix is derived considering ice loads in the X, Y, and Z direction simultaneously. Furthermore the location of ice loads acting on hull-plate may fall outside the measuring sensor area, and the enhanced influence coefficient matrix is modified to reduce the difference between the actual and the estimated ice loads by expanding the domain outward from the sensor area. The developed method for enhanced influence coefficient matrix is applied to IBRV ARAON during the 2019 Antarctic ice field test and the local ice loads in three directions are efficiently calculated compared to those by a conventional method.

• 대한조선학회논문집
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• 제49권1호
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• pp.45-51
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• 2012

Sea ice properties have been considered a key indicator in the structural design criteria of icebreaking vessels and arctic offshore platforms to estimate design ice load and resistance for their safety management in Arctic Ocean. A measurement study of sea ice properties was conducted during July to August of 2011 with the Korean icebreaking research vessel "Araon" around Chukchi Borderland. The sea ice concentration appears to be rapidly decreasing during this cruise. Ice condition seems to be thick second-year ice and multi-year ice and then, a lot of melt ponds were observed in the surface of ice floe. Calculated flexural strength of sea ice was about 250~550kPa, ice thickness was roughly 1.3~3.0m. In this research we performed field experiment to measure ice temperature along the depth, thickness, density, salinity, brine volume ratio and crystal structure. Apparent conductivities derived with the electromagnetic induction instrument were compared to drill hole measurement results and accuracy of sea ice thickness estimation formula was discussed.

• 한국해양공학회지
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• 제27권5호
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• pp.82-87
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• 2013

The icebreaking research vessel ARAON conducted her second ice trial in the Arctic Ocean during the summer season of 2010. During this voyage, the local ice loads acting on the bow of the port side were measured using 14 strain gauges. The measurement was carried out during icebreaking while measuring the thickness of the ice every 10 m. The obtained strain data were converted to the equivalent stress values, and the effects of the ship speed and ice thickness on the ice load were investigated. As a result, it was found that a faster speed produced a larger stress, according to the variation in the peak values below an ice thickness condition of 1.5 m. Meanwhile, the effect of the ice thickness on the ice load was not clear.

• 한국항해항만학회지
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• 제37권2호
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• pp.143-148
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• 2013

본 연구의 목적은 빙해역을 운항하는 선박의 쇄빙시 깨진 해빙에 의해 선수부 좌현 외판에 작용하는 국부 빙하중을 계측한 신호의 특성을 조사하는 것이다. 한국 최초의 쇄빙연구선인 아라온호를 이용하여 2010년 8월초 북극해에서 실선 시험을 수행하여 선수부에 설치된 변형률 게이지로부터 국부적인 빙하중에 의한 신호를 계측하였다. 국부적인 빙하중에 의한 구조 응답 특성을 반영한 계측 신호는 전형적인 유체 충격압에 대한 하중-시간 이력과 다소 다른 특성을 갖는 것도 있음이 파악되었다. 본 연구에서는 계측 신호에 대한 시간 이력을 분석하고, 무차원화된 특성값들로 나타내었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권1호
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• pp.66-72
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• 2016

The aim of this paper is to investigate the characteristics of the signal of local ice load acting on side shell in the bow part due to ice broken by an icebreaker in ice-covered waters. The Korean icebreaking research vessel "ARAON" voyaged to the Arctic Ocean during the summer of 2010, and measurements of local ice load were carried out using several strain gauges. In this study, the time history of measured signals was analyzed and the characteristic values including rising time and half-decaying time were presented using non-dimensional parameters.

• 한국해양공학회지
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• 제28권6호
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• pp.527-532
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• 2014

The thickness of Arctic sea ice is a particularly significant factor in Arctic shipping and other ice-related research areas such as scientific sea ice investigations and Arctic engineering. In this study, the relation between the measured sea ice thickness and freeboard on the Chukchi and Beaufort Seas during the 2010 and 2011 Arctic cruise of the icebreaking research vessel "Araon" were considered. An assumption of hydrostatic equilibrium was used to estimate the ice thickness as a function of the freeboard. Then, to examine the degree of error, a sensitivity analysis of the thickness estimation of the sea ice was conducted. The error in the density and depth of the snow and the error in the density of the seawater were subordinate parameters, but the density of the ice and the freeboard were the primary parameters in the error calculation. The presented relation formula showed fairly close agreement between the calculated and measured results at a freeboard of >0.24 m.

• 대한조선학회논문집
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• 제49권2호
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• pp.189-195
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• 2012

The ice trials of the first Korean icebreaking research vessel "ARAON" were performed at the Arctic Ocean in July-August 2010. The sea ice concentrations of Arctic Ocean were 4/10 to 10/10 and the range of sea ice thickness was roughly 1.0 to 3.5m. In this research, sea ice thickness characteristics at the old ice floes were determined from results of drill hole and apparent conductivity measurements. Especially we measured apparent conductivity using an electromagnetic induction instrument (EM31-MK2) and estimated the sea ice thickness through the empirical equation from Cold Regions Research & Engineering Laboratory, CRREL. The results of estimated sea ice thickness were compared to drill hole measurement results and then, we suggest the new empirical equation to estimate sea ice thickness of single layer type sea ice during the summer season of Arctic Ocean by curve fitting approach to these data.