Investigation of accumulated plastic damages on ship plates subjected to repeated ice impacts

In connection with the Statoil SKT project, DNV GL have developed a method for estimating ice loads on the ship hull structure and mooring tension of the anchor handling tug supply (AHTS) vessel Magne Viking by full scale measurements. In March 2017, the vessel was equipped with an extensive measurement system as a preparation for the dedicated station-keeping trial in drifting ice in the Bay of Bothnia. Data of the ice impacts acting on the hull were collected over the days of testing together with several other parameters from the ship propulsion system. Whilst moored, the tension in the mooring chain was monitored via a load cell and logged simultaneously to the other parameters. This paper presents the processes involved in developing the measurement concept, including the actual installation and execution phases. The basic philosophy behind the system is described, including the methods used to design an effective measurement arrangement, and develop procedures for estimation of ice loads based on strain measurements. The actual installation and the process of obtaining the recorded data sets are also discussed.

Download Full-text

Validating Ice Impacts Using Adaptive Smoothed Particle Hydrodynamics for Planetary Defense

2019 15th Hypervelocity Impact Symposium ◽

10.1115/hvis2019-102 ◽

2019 ◽

Author(s):

Dawn Graninger ◽

Megan Bruck Syal ◽

J. Michael Owen ◽

Paul Miller

Keyword(s):

Smoothed Particle Hydrodynamics ◽

Weibull Modulus ◽

Damage Model ◽

Water Ice ◽

Hazardous Object ◽

Planetary Defense ◽

Particle Hydrodynamics ◽

Smoothed Particle ◽

Ice Impacts ◽

Adaptive Smoothed Particle Hydrodynamics

Abstract Understanding how a potentially hazardous object (PHO) responds to a kinetic impactor is of great interest to the planetary defense community. Target response depends upon the detailed material properties of the PHO, which may not be well constrained ahead of time. Hence, it is useful to explore a variety of target compositions for kinetic impact deflection. Previous validation efforts have focused primarily on understanding the behavior of common rocky materials, though PHOs are not exclusively composed of such material. Water ice is one material for which there has been only limited code validation against cratering experiments. It is known that comets consist of primarily icy material and some asteroids likely contain some amount of ice. Therefore, it is useful to understand the model sensitivities for ice in deflection simulations. Here we present Adaptive Smoothed Particle Hydrodynamics simulations of impacts into water ice by an aluminum projectile. We explore the sensitivities to the damage model within our code and find that the best-fit simulations of ice occur with a Weibull modulus of 12, though results can be obtained with values of the Weibull modulus near the published value of 9.59. This work demonstrates the efficacy of using an adaptive smoothed particle hydrodynamics code to simulate impacts into ice.

Download Full-text

Numerical simulation of ice impacts on ship hulls in broken ice fields

Ocean Engineering ◽

10.1016/j.oceaneng.2019.03.043 ◽

2019 ◽

Vol 180 ◽

pp. 162-174 ◽

Cited By ~ 7

Author(s):

Jeong-Hwan Kim ◽

Yooil Kim ◽

Hyun-Soo Kim ◽

Seong-Yeob Jeong

Keyword(s):

Numerical Simulation ◽

Ship Hulls ◽

Broken Ice ◽

Ice Impacts

Download Full-text

Hydraulic Damper Concept for Thruster Ice Impact Load Reduction

ASME/BATH 2017 Symposium on Fluid Power and Motion Control ◽

10.1115/fpmc2017-4238 ◽

2017 ◽

Author(s):

Lauri Siivonen ◽

Kalevi Huhtala

Keyword(s):

Impact Load ◽

Impact Loads ◽

Load Reduction ◽

Arctic Seas ◽

Hydraulic Damper ◽

Shaft Line ◽

Positive Effects ◽

Open Sea ◽

Torsional Loads ◽

Ice Impacts

Steerable thrusters are used to maneuver a vessel in open sea environment. The harsh environment of arctic seas introduces certain challenges with propellers hitting ice and decreasing lifetime of the system, as the loads generated by ice impacts are significantly higher than nominal loads. Damping of an ice impact load is a difficult task since the impacts have high torsional loads and they occur only in a fraction of the lifetime of the system. Commercial dampers are hard to find since they do not generally have the capacity for damping such high loads. The proposed active hydraulic damper reduces ice impact loads by accelerating and decelerating the shaft line. The lack of space and commercial components narrow down the possibilities but simulation results with the system show some positive effects in typical ice impact scenario. The system also recuperates most of the used energy and stores it to accumulator.

Download Full-text

Innovative Ice Protection for Shallow Water Drilling: Part I — Presentation of the Concept

Volume 2: Ocean Engineering and Polar and Arctic Sciences and Technology ◽

10.1115/omae2006-92181 ◽

2006 ◽

Cited By ~ 2

Author(s):

Arne Gu¨rtner ◽

Ove Tobias Gudmestad ◽

Alf To̸rum ◽

Sveinung Lo̸set

Keyword(s):

Shallow Water ◽

Shallow Waters ◽

Drilling Rig ◽

Modular Concept ◽

Drilling Operations ◽

Drifting Ice ◽

Ice Impacts ◽

Jack Up ◽

Near Future ◽

Ice Period

Recent discoveries of hydrocarbons in the shallow waters of the Northern Caspian Sea arise the need for intensive drilling activities to be carried out in the near future in order to explore the potentials. Experience with mobile drilling units in the seasonally ice infested waters solely originates from the current drilling campaign of the Sunkar drilling barge at Kashagan and Kalamkas. However, with increased drilling activities upcoming, innovative drilling concepts are desirable due to the objective of maintaining drilling operations during the ice period with conventional non-ice-resistant drilling platforms. Hence, this paper suggests the employment of external Shoulder Ice Barriers (SIBs) to protect a conventional jack-up drilling rig from the hazards of drifting ice in shallow water. The SIB’s design is suggested to increase the ice rubble generation at the ice facing slope and thereby provide sufficient protection from drifting ice impacts. The modular concept of the SIB makes it possible to deploy each module in a floating mode to site, whereupon they are ballasted and connected to each other, forming a sheltered position for the jack-up. Subsequent to the termination of the drilling campaign the SIB modules may be retrieved by de-ballasting and tow out, without having significant impact on the environment. This paper presents, on a technical feasible level, the concept of ice protection in shallow water by means of SIBs.

Download Full-text