Samcot_annual_report

Annual Report 2016

SAMCoT

Large-scale field fracture tests

Svea, Van Mijenfjord, Spitsbergen, March 2016. After

extensive preparations and an impeccable implemen-

tation coordinated by Lu, the ‘fracture research team’

obtained valuable data and was able to observe visually,

for the first time, a stable crack growth within sea ice.

This is unusual, as in other test scenarios the crack

propagates in an uncontrolled manner. Due to the

success of the experiment and the results achieved,

another field test is planned in 2017 with higher

fracture loading rates. The study of fracture events

is highly relevant to our industry partners. During ice

management, parallel channels are created to facilitate

the ice floe size reduction process and fracturing events

are constantly observed. Data obtained during the Oden

Arctic Technology Research Cruise in 2015 (OATRC’15)

show many parallel channel fracturing events. Dr. Lu

analyzed the Oden data and programmed a numerical

scheme based on the Extended Finite Element Method

(XFEM) to simulate the crack kinking process and to

explain the observed fracture events.

Observed and modelled fracturing of sea ice

In 2016, researcher Hongtao Li, in collaboration with

Ceetron, used Lu’s analytical fracture solutions to im-

prove the computational efficiency of Simulator of Arctic

Marine Structures (SAMS). Results of the use of Wenjun

Lu’s analytical fracture solutions are shown here.

The figure illustrates a simulation

of a predicted crack path versus the

crack path in reality. The exact pre-

diction was not made, but the general

trend and direction were captured.

GLOBAL ICE ACTIONS

Fracturing of ice

For postdoc Wenjun Lu, 2016 was another busy and

exciting year on several interesting research fronts

covering field tests, theoretical and numerical studies

and model tests.

The fracture team in Svea from left to right: Petter Scharffscher (M-Tech), Aleksey Shestov

(SAMCoT postdoc at UNIS & key participant), Wenjun Lu (main researcher, NTNU),

Xiaodong Chen (NTNU), John Dempsey (Clarkson University, USA), Jukka Tuhkuri

(Aalto University) and Sveinung Løset (NTNU).

Towing test without fracture

Ilija Samardzija’s MSc thesis focused on answering what

happens if there is no fracture during the interaction

between ice and a structure? Supervised by Lu (seen

in the picture in the background), Samardzija (on the

right) conducted a series of model tests by towing a

structure in various ice conditions. Floe ice made from

paraffin was used to represent ice fields of various

concentrations, floe shapes and sizes. The towing force

was measured together with the trajectories of each ice

floe during the interaction.

Splitting failure takes place

Local bending failure