Testing in Ice Mikko Suominen Content of the lecture - - PowerPoint PPT Presentation

Mikko Suominen

MEC-E4004 - Model Scale Testing in Ice

Content of the lecture

• Introduction
• The course
• Aim, time table, practicalities
• Sea Ice
• Occurence
• Conditions
• Properties
• Wrap up, the next lecture

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Introduction

• Mikko Suominen
• M.Sc in Marine Technology 2011
• Doctoral Student / Ice Tank manager
• Uncertainty and variation in the measured ice-

induced loads on the ship hull

• Expected defense in Jan/Feb 2018
• Other hobbies wrestling, triathlon
• Introduction round
• Your motivation to be on this course?

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The aim of the course

• To introduce students to principles of ice model scale testing
• Give hands on experience about conducting model scale testing
• After the course, the student
• has a general understanding about sea ice existence and properties
• understands the principles of conducting model scale testing in ice
• can conduct and report model scale tests in ice
• has experience on peer-review and presentation

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• 3 lectures
• Model scale tests in ice
• Seminar (presentation)
• Peer-review
• Final reporting
• Grading
• 25% seminar, 25% peer-review
• 50% final reporting

Content of the course

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Time table

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Mon, Oct 30, 14-16 – 1st lecture Mon, Nov 6, 14-16 – 2nd lecture, Tue Nov 7, 8-15 –Testing in AAT Mon, Nov 13, 14-16 – 3rd lecture Mon, Nov 20, 14-16 – No lecture Mon, Nov 24, 23:59 – DL to send the report for peer review Mon, Dec 4, 14-16 – Seminar and return of the reviewed report Mon, Dec 8, 23:59 – DL for the final report

For meetings: address Tietotie 1 C email mikko.suominen@aalto.fi

Questions?

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? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

The aim and learning outcomes of the lecture

• To introduce students to sea ice
• After the lecture students know
• where and what kind of sea ice conditions exists
• the basics of the sea ice growth and structure
• Has general knowledga about the mechanical properties of sea ice

Discussion

• What do you know about ice?

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Sea ice

Occurrence – Arctic

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http://www.polarview.org/

Sea ice

Occurrence – Antarctic

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http://www.polarview.org/

Sea ice

Occurrence – other areas

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Baltic Sea Caspian Sea Great Lakes Bohai Sea Sea of Okhotsk

Sea ice

Conditions – growth

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• The main parameter for the ice thickness growth is the

cumulative sum of freezing temperatures of air

• Zubov (1938, 1945) based on empirical data
• H = ice thickness, α1 and α2 = empirical factors, FFD = freezing

degree-days

• FFD accounts the degrees below the freezing point of the water
• Salinity in Oceans 35 ‰ and freezing point at -4oC, in the Baltic Sea

3-6 ‰ at surface and freezing point -0.3oC

• For the Baltic Sea α1 =50 and α2 = 8 (Frederking et al., 2005)
• Theoretically, the growth of ice thickness can be understood

based on heat balance: ”heat input = flux out”

𝐼2 + 𝛽1𝐼 = 𝛽2𝐺𝐺𝐸

(Maykut, 1986, based on Anderson, 1961)

Sea ice

Conditions – growth

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• Growth of the multiyear ice

(Maykut and Untersteiner, 1971)

Sea ice

Conditions – growth & conditions

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• Ice Growth Process
• Calm sea:
• Frazil ice  Grease ice  Nilas  (possible Rafting ) Ice sheet
• Rough Sea
• Frazile ice  Pancake ice  (possible Rafting or Ridging ) Ice Sheet

video

Sea ice

Conditions - Ridges

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(Polojärvi, 2013)

Sea ice

Conditions – Ice Channel

• Especially on the fast ice area ice channels are formed when

ships use the same route

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(Sandkvist, 1978)

Sea ice

Conditions - structure

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• The top layer randomly oriented

crystals

• The best oriented c-axia starts to

dominate the growth

• Transitiom from random to columnar
• Columnar ice is not isotropic

(Perey and Pounder, 1958)

Sea ice

Conditions - structure

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Sea ice

Properties

• The properties depend on temperature, structure, orientation, brine volume,

porosity, strain rate, and scale.

• Single values should not be given.
• Sea ice is a natural material, all properties have statistical nature.
• Many properties appear to depend on the measurement procedure
• Many sea ice properties depend on the ice conditions and season also
• Ice can not be described by purely brittle, plastic or viscous material – not

isotropic material

• Compressive and flexural strength, and Young’s modulus the most interesting for

structures and model scale testing

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Sea ice

Properties – Compressive strength

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• Ice failure under compression a complex process
• Various failure modes – partly speed dependent

(Riska, 1994) (after Frederking, 1977)

Sea ice

Properties – Compressive strength

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• Different test set-ups to measure compressive strength

(Timco & Weeks, 2010)

Sea ice

Properties – Compressive strength

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• Pressure area curve applied for design purposes

(Sanderson, 1988)

Sea ice

Properties – Compressive strength

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• Pressure area curve applied for design purposes

(Masterson et al., 2007) (Taylor et al., 2010)

Sea ice

Properties – Flexural strength

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• Two approaches to measure: cantilever beam test and

simple beam test

• In situ cantilever beams are typically used
• High scatter in the results e.g. due the stress concentration at the

root

• In simple beam test, the beam is loaded from 3 or 4

points

• Four point bending the most reliable
• Both tests assume the ice in the homogeneous and

perfectly elastic

•  Flexural strength ~ Tensile strength
• Not true for ice
• Flexural strength an index value
• However significant for many reasons

(Kujala, 1994)

F

Sea ice

Properties – Flexural strength

• Measured flexural strength values

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(Kujala, 1994) (Timco & Weeks, 2010) Flexural strength [kPa]

Sea ice

Properties – Young’s modulus

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(Langleben and Pounder,1963)

• Measured values vary from 1.7 to 5.7 GPa when measured by flexural waves and

from 1.7 to 9.1 GPa when determined by body-wave velocities

• The flexural wave velocity is controlled by the overall properties of an ice sheet
• The body-wave velocity is controlled by the high velocity channel in the commonly colder,

less saline and stronger upper section of the ice

•  The difference is reasonable
• Note! mechanical measurement (in situ cantilever

beam etc.) of the Modulus is not truly elastic

• Ice is not truly elastic
• Called Effective Modulus or the Strain Modulus.

(Timco & Weeks, 2010)

Wrap-up

• What is the difference between the open water hull form with

respect to ice going vessel? Why?

• Could a good open water vessel be good in ice conditions?

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The next time

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• Focus on
• Ship performance in ice
• How properties and conditions are scale
• Practicalities of conducting model scale

tests

Thank you!

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References

Anderson, D., 1961. Growth rate of sea ice. J Glaciol 3(30):1170–72. Frederking R., Kouts T., Riska, K., 2005. In: Kujala, P., Suominen, M., Jalonen, R. (Eds.). Increasing the Safety of Icebound Shipping – Final Scientific Report: Vol 1 and 2. Helsinki University of Technology, Ship Laboratory, Report M- 302, Espoo, Finland, 2007, Deliverable D 4-1. August, 2005. Frederking, R.M.W., 1977. Plane-strain compressive strength of columnar-grained and granular snow-ice. Journal of Glaciology 18, 505–516. Kujala, P., 1994. On the Statistics of Ice Loads on Ship Hull in the Baltic. Doctoral Thesis, Helsinki University of Technology, Ship Laboratory, Acta Polytechnica Scandinavica Mechanical Engineering Series No. 116, 98 p. Langleben, M., Pounder, E., 1963. Elastic parameters of sea ice. In: Kingery, W.D. (Ed.), Ice and Snow. MIT Press, USA,

• pp. 69–78.

Masterson, D.,Frederking, R., Wright, B., Karna, T., Maddock, W., 2007. A REVISED ICE PRESSURE-AREA CURVE, POAC-07, Dalian, China, June 27-30, 2007. Maykut, G., 1986. The surface heat and mass balance. In The geophysics of sea ice, ed. N. Untersteiner, 395–463. New York: Plenum Press. Maykut, G., Untersteiner, N., 1971. Some results from a time dependent thermodynamic model of sea ice. JGR 76(6):1550–75. Polojärvi, P., 2013. Sea ice ridge keel punch through experiments: model experoiments and numerical modeling with discrete and combined finite-discrete ekement methods. Doctoral Thesis, Aalto University.

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References

Perey, F., Pounder, E., 1958. Crystal orientation in ice sheets. Canad J Phys 36:494–502. Riska, K., 1994. Models of ice-structure contact for engineering applications. In: Selvadurai, A., Boulon, M., (Eds.) Mechanics of geomaterial interfaces. Sanderson, T., 1988. Ice Mechanics: Risk to Offshore Structures. Graham & Trotman, London, UK; 1988. Sandkvi.st, J., 1978. Problems in Keeping Year-Round Navigation in the Luleå Harbour, IAHR-78 Taylor, R., Jordaan, I., Li, C., Sudom, D., 2010. Local Design Pressure for Structures in Ice: Analysis of Full-Scale Data. Journal of Offshore Mechanics and Arctic Engineering, Aug 2010, Vol 132 Timco, G., Weeks, W., 2010. A review of the engineering properties of sea ice. Cold Regions Science and Technology 60,

• pp. 107-129.

Weeks, W., 2010. On Sea Ice. University of Alaska Press. Zubov, N., 1938. On the maximum thickness of perennial sea ice (R). Meteorol Gidrol 4:123–31. Zubov, N., 1945. Arctic ice (US Navy Electronics Laboratory translation, NTIS no. AD 426972; originally published in Russian by Izdatel’stvo Glasevmorputi in 1943).

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