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Papers by Petri Varsta
Composite Structures, Jun 1, 2006
In this paper recent developments to model ship-ice contact and to evaluate design ice loads are ... more In this paper recent developments to model ship-ice contact and to evaluate design ice loads are summarised. The focus is on first year ice appearing annually in the Baltic Sea. The most important parameters to specify characteristics of ice cover for winter navigation purposes are presented. Observations on ship-ice contact suggest that the contact has a line-like nature. This concept is summarised and it's implications to structural design are discussed. An equivalent level ice thickness approach which includes the effect of ridges on the ice loads is described. The effect of ship parameters on the load level, based on the physical background for ice loads on different parts of a ship hull is given. A method to estimate the life-time ice loads on different parts of the hull of a vessel navigating in the Baltic Sea is developed, and the calculated loads are compared with measured long-term ice loads onboard MS KEMIRA, MS ARCTURUS and IB SISU. Finally the risk of damage caused by ice loads on ships in the Baltic Sea is discussed.
Transactions of the Society of Naval Architects and Marine Engineers, 2011
Ships and Offshore Structures, Mar 1, 2012
A survey of existing ice edge failure models is made, and some suggestions to improvements in the... more A survey of existing ice edge failure models is made, and some suggestions to improvements in these models are presented. The observed failure process of ice plate under various loading conditions is described. The process is then divided into physically different details such as crushing, shearing and bending, based on literature survey and observations made at sea. Results from tests made with fresh water beams are reported, and determination of compressive elastic constants of columnar grained fresh water ice is dealt with. Order from NSFI as No. 19954.
Sea transport in the Arctic regions represents just a small part of the world's total shippin... more Sea transport in the Arctic regions represents just a small part of the world's total shipping, not least because of the difficult environmental conditions encountered in these areas. Winter navigation started about a hundred years ago in the sub-arctic sea areas, where ice cover exists only during the winter months. Navigation in the Arctic proper began about a half century ago. The sailing period increases from year to year with the final goal obviously being year round traffic at a tolerable cost. This phase was reached in the Baltic in the early 1970s. The paper aims to give a general idea of the basic questions in polar sea transport systems. The demand for transportation and the influence on cargo handling systems and ship technology are discussed. However, details of technical solutions are, as far as possible, avoided.
This tanker is described under the main headings of (i) time and test area, (ii) ice pressure, (i... more This tanker is described under the main headings of (i) time and test area, (ii) ice pressure, (iii) speed measurements, (iv) power measurements, (v) ice measurements, (vi) turning test, and (vii) relationship between ice pressure and structural response of the ship. The results are tabulated and illustrated by graphs and histograms.
Proceedings of the 11th International Congress of the International Maritime Association of the Mediterranean, Lisbon, Portugal, 26-30 September 2005, 2006
Advanced Ship Design for Pollution Prevention, 2010
The paper describes the measuring system onboard the icebreaker including the data collector syst... more The paper describes the measuring system onboard the icebreaker including the data collector system, ice pressure gauges, strain gauges, and the calibration of the ice pressure gauges. The weather and ice conditions in the Baltic during the winter of 1978 are stated. The following results of the measurements are discussed: Daily pressure maxima. Daily recordings. Statistical analysis. Influence of external conditions, and connection between ice pressure and ice-induced stress. Order from NSFI as No. 19966.
Composite Structures, Jun 1, 2006
In this paper recent developments to model ship-ice contact and to evaluate design ice loads are ... more In this paper recent developments to model ship-ice contact and to evaluate design ice loads are summarised. The focus is on first year ice appearing annually in the Baltic Sea. The most important parameters to specify characteristics of ice cover for winter navigation purposes are presented. Observations on ship-ice contact suggest that the contact has a line-like nature. This concept is summarised and it's implications to structural design are discussed. An equivalent level ice thickness approach which includes the effect of ridges on the ice loads is described. The effect of ship parameters on the load level, based on the physical background for ice loads on different parts of a ship hull is given. A method to estimate the life-time ice loads on different parts of the hull of a vessel navigating in the Baltic Sea is developed, and the calculated loads are compared with measured long-term ice loads onboard MS KEMIRA, MS ARCTURUS and IB SISU. Finally the risk of damage caused by ice loads on ships in the Baltic Sea is discussed.
Transactions of the Society of Naval Architects and Marine Engineers, 2011
Ships and Offshore Structures, Mar 1, 2012
A survey of existing ice edge failure models is made, and some suggestions to improvements in the... more A survey of existing ice edge failure models is made, and some suggestions to improvements in these models are presented. The observed failure process of ice plate under various loading conditions is described. The process is then divided into physically different details such as crushing, shearing and bending, based on literature survey and observations made at sea. Results from tests made with fresh water beams are reported, and determination of compressive elastic constants of columnar grained fresh water ice is dealt with. Order from NSFI as No. 19954.
Sea transport in the Arctic regions represents just a small part of the world's total shippin... more Sea transport in the Arctic regions represents just a small part of the world's total shipping, not least because of the difficult environmental conditions encountered in these areas. Winter navigation started about a hundred years ago in the sub-arctic sea areas, where ice cover exists only during the winter months. Navigation in the Arctic proper began about a half century ago. The sailing period increases from year to year with the final goal obviously being year round traffic at a tolerable cost. This phase was reached in the Baltic in the early 1970s. The paper aims to give a general idea of the basic questions in polar sea transport systems. The demand for transportation and the influence on cargo handling systems and ship technology are discussed. However, details of technical solutions are, as far as possible, avoided.
This tanker is described under the main headings of (i) time and test area, (ii) ice pressure, (i... more This tanker is described under the main headings of (i) time and test area, (ii) ice pressure, (iii) speed measurements, (iv) power measurements, (v) ice measurements, (vi) turning test, and (vii) relationship between ice pressure and structural response of the ship. The results are tabulated and illustrated by graphs and histograms.
Proceedings of the 11th International Congress of the International Maritime Association of the Mediterranean, Lisbon, Portugal, 26-30 September 2005, 2006
Advanced Ship Design for Pollution Prevention, 2010
The paper describes the measuring system onboard the icebreaker including the data collector syst... more The paper describes the measuring system onboard the icebreaker including the data collector system, ice pressure gauges, strain gauges, and the calibration of the ice pressure gauges. The weather and ice conditions in the Baltic during the winter of 1978 are stated. The following results of the measurements are discussed: Daily pressure maxima. Daily recordings. Statistical analysis. Influence of external conditions, and connection between ice pressure and ice-induced stress. Order from NSFI as No. 19966.