IceSense Proof of Concept: Calibrating an Instrumented Figure Skating Blade to Measure On-Ice Forces

Competitive figure skaters often suffer from overuse injuries, which may be due to the high impact forces endured during jump repetitions performed in practice and competition. However, to date, forces during on-ice figure skating have not been quantified due to technological limitations. The purpose of this study was to determine the optimal calibration procedure for a previously developed instrumented figure skating blade (IceSense). Initial calibration was performed by collecting data from the blade while 11 skaters performed off-ice jumps, landing on a force plate in the lab. However, mean peak force measurements from the blade were greater than the desired error threshold of ±10%. Therefore, we designed a series of controlled experiments which included measuring forces from a load cell rigidly attached to the top of the blade concurrently with strain data from the strain gauges on the blade. Forces were applied to the blade by adding weight to a drop tower or by manually applying force in a quasi-static manner. Both methods showed similar accuracy, though using the drop tower allowed precise standardization. Therefore, calibration was performed using the weighted drop method. This calibration was applied to strain gauge data from out-of-sample drop trials, resulting in acceptable estimates of peak force (less than 10% error). Using this calibration, we collected data on one figure skater and present results from an exemplar on-ice double flip jump. Using the IceSense device to quantify on-ice forces in a research setting may help inform training, technique, and equipment design.

Evaluation of the relative contribution of meteorological and oceanic forces to the drift of ice islands offshore Newfoundland

On 29 April 2015, four beacons were deployed onto an ice island in the Strait of Belle Isle to record positional data. The ice island later broke up into many fragments, four of which were tracked by the beacons. The relative influences of wind drag, current drag, Coriolis force, sea surface height gradient and sea-ice force on the drift of the tracked ice island fragments were analyzed. Using atmospheric and oceanic model outputs, the sea-ice force was calculated as the residual of the fragments' net forces and the sum of all other forces. This was compared against the force obtained through ice concentration-dependent relationships when sea ice was present. The sea-ice forces calculated from the residual approach and concentration-dependent relationships were significant only when sea ice was present at medium-high concentrations in the vicinity of the ice island fragments. The forces from ocean currents and sea surface tilt contributed the most to the drift of the ice island fragments. Wind, however, played a minimal role in the total force governing the drift of the four ice island fragments, and Coriolis force was significant when the fragments were drifting at higher speeds.

Eliminating the Uncertainties in Hydraulic and Ice Loads on Berm Breakwaters

A model for the computation of failure probabilities for partly reshaping mass-armored berm breakwaters in the Arctic is presented. The model consists of a reliable tool for the design of port structures in the rapidly changing Arctic environment and considers the simultaneous effects of wave and ice forces. The applied probabilistic approach was based on Bayesian inference. Hydrodynamic and ice historical data from Prudhoe Bay, Alaska were collected and analyzed to supply the Bayesian network with a large pool of information for the analysis. The model performed real-time predictions based on historical data and the user’s prior knowledge and assigned relevant values to load and resistance parameters. The predictive skill of the Bayesian network was validated with log-likelihood tests. Furthermore, the main outputs were applied for a Level III (fully probabilistic) reliability assessment of the structure. The study shows that a well-formulated Bayesian network can be a powerful tool in the design process and for the purpose of reliability analysis of coastal structures in highly unpredictable environments, such as the Arctic. The model can represent the dependencies between wave and ice loads in relation to the characteristics of the breakwater, as well as, its response. The average deviation of computed probabilities of failure relative to the prior estimates was 58.7%.

Interaction of Ice Force in Ship-Ship Collision

The maritime transportation system in the Northern Baltic Sea (NBS) is complex and operates under varying environmental conditions. The most challenging conditions relate to the presence of ice-cover, which for the NBS e.g. for the Gulf of Finland or Bay of Bothnia, can remain up to several months. The number of maritime accidents in these two areas is the highest during winter season, which can involve accidents like groundings, collisions, damages due to the ice etc. The paper presents the model to predict the ice interaction in ship-ship collision dynamics. The ice forces are included in the time-domain simulation model and also in a simplified model based on the momentum conservation. The simplified model is proposed for a rapid estimation of increase in deformation energy due to the presence of ice forces. The analysis shows that the ice influence depends strongly on the ship mass, ice thickness and collision speed. The maximum increase in the deformation energy in the studied collision scenarios was up to 19%.

Coastal Ice Investigation on the Site of Further Bridge Construction - Sveagruva, Svalbard, Norway

Sveagruva is a mining settlement in the Norwegian archipelago of Svalbard, lying in the head of Van Mijenfjord. A bridge to the opposite site of the fjord is planned to be constructed for further mine development, so investigations of coastal ice forces on one of the future bridge suspensions were held.

Ice Nonsimultaneous Failure, Bending and Floe Impact Modeling for Simulating Wind Turbine Dynamics Using FAST

Many promising locations for developing offshore wind energy are in cold regions. This type of environment introduces one important technological challenge for offshore wind turbine design: the impact of floating surface ice. Recent developments to add an ice-loading module to the wind turbine computer-aided-engineering tool FAST are described in this paper. These efforts enable FAST, developed and maintained by the National Renewable Energy Laboratory, to simulate the impact of ice on offshore wind turbines. The ice-loading module includes different ice mechanics models that address various ice properties, failure modes, and ice-structure interaction mechanisms. In a previous OMAE symposium paper, models for quasi-static crushing, transient dynamic ice breakage, and random forcing for the ice module were described. In this paper, three new models are presented. One model evaluates the ice-loading effective pressure reduction caused by ice nonsimultaneous failure in discrete local zones across the contact area. The second model generates time-dependent ice forces on conical structures caused by bending failure. The third model is used to simulate large ice floe interaction with wind turbine support systems. This third model describes ice forces that are limited by momentum or splitting failure of ice floes. These models are integrated in the FAST modularization framework and allow for the simulation of coupled ice force, ice floe motion, and wind turbine structure response. This paper also presents example numerical simulation results of wind turbine dynamics using FAST coupled with these three new models.