Developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamic response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind turbines subjected to forces resulting from ice impact on the turbine support structure. The conditions considered in this module are specifically addressed in the International Organization for Standardization (ISO) standard 19906:2010 for arctic offshore structures design consideration. Special consideration of lock-in vibrations is required due to the detrimental effects of such response with regard to fatigue and foundation/soil response. The use of FAST for transient, time domain simulation with the new ice module is well suited for such analyses.

References

References
1.
Tarp-Johansen
,
N. J.
,
2005
, “
Partial Safety Factors and Characteristic Values for Combined Extreme Wind and Wave Load Effects
,”
ASME J. Sol. Energy Eng.
,
127
(
2
), pp.
242
252
.
2.
Jonkman
,
J.
,
Butterfield
,
S.
,
Musial
,
W.
, and
Scott
,
G.
,
2009
, “
Definition of a 5-MW Reference Wind Turbine for Offshore System Development
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/TP-500-38060.
3.
Jonkman
,
J. M.
, and
Marshall
,
L. B.
,
2005
, “
FAST User's Guide
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/EL-500-38230.
4.
Kärnä
,
T.
,
1992
, “
A Procedure for Dynamic Soil-Structure-Ice Interaction
,”
International Offshore and Polar Engineering Conference
, pp.
764
771
.
5.
Ashby
,
M.
,
Palmer
,
A.
,
Thouless
,
M.
,
Goodman
,
D.
,
Howard
,
M.
,
Hallam
,
S.
,
Murrell
,
S.
,
Jones
,
N.
,
Sanderson
,
T.
, and
Ponter
,
A.
,
1986
, “
Nonsimultaneous Failure and Ice Loads on Arctic Structures
,”
Offshore Technology Conference
, pp. 399–404.
6.
Sodhi
,
D.
,
1998
, “
Nonsimultaneous Crushing During Edge Indentation of Freshwater Ice Sheets
,”
Cold Reg. Sci. Technol.
,
27
(
3
), pp.
179
195
.
7.
Kärnä
,
T.
,
Lubbad
,
R.
,
Løset
,
S.
,
Mroz
,
A.
,
Dalane
,
O.
,
Bi
,
X.
, and
Xu
,
N.
,
2010
, “
Ice Failure Process on Fixed and Compliant Cones
,”
HYDRALAB Joint User Meeting
, Hannover, Germany.
8.
Mróz
,
A.
,
Holnicki-Szulc
,
J.
, and
Kärnä
,
T.
,
2008
, “
Mitigation of Ice Loading on Off-Shore Wind Turbines: Feasibility Study of a Semi-Active Solution
,”
Comput. Struct.
,
86
(
3
), pp.
217
226
.
9.
Bhat
,
S.
,
Choi
,
S. K.
,
Wierzbicki
,
T.
, and
Karr
,
D. G.
,
1991
, “
Failure Analysis of Impacting Ice Floes
,”
ASME J. Offshore Mech. Arct. Eng.
,
113
(
2
), pp.
171
178
.
10.
Jonkman
,
J.
,
2013
, “
FAST Theory Manual
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/TP-500-32449.
11.
Laino
,
D. J.
, and C., H. A.,
2002
, “
User's Guide to the Wind Turbine Dynamics Aerodynamics Computer Software AeroDyn
,” National Renewable Energy Laboratory Under Subcontract No. tcx-9-29209-01, Windward Engineering LLC, Salt Lake City, UT.
12.
Moriarty
,
P. J.
, and
Hansen
,
A. C.
,
2005
, “
AeroDyn Theory Manual
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/EL-500-36881.
13.
Jonkman
,
J.
,
2007
, “
Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/TP-500-41958.
14.
Jonkman
,
J.
,
2009
, “
Dynamics of Offshore Floating Wind Turbines-Model Development and Verification
,”
Wind Energy
,
12
(
5
), pp.
459
492
.
15.
Damiani
,
R.
, and
Song
,
H.
,
2013
, “
Assessing the Importance of Nonlinear Structural Characteristics in the Development of a Jacket Model for the Wind Turbine CAE Tool FAST
,”
32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE2013)
.
16.
Song
,
H.
,
Damiani
,
R.
,
Robertson
,
A.
, and
Jonkman
,
J.
,
2013
, “
A New Structural-Dynamics Module for Offshore Multimember Substructures Within the Wind Turbine CAE Tool FAST
,”
23rd International Ocean and Polar Engineering Conference
.
17.
Jonkman
,
J.
,
2013
, “
The New Modularization Framework for the FAST Wind Turbine CAE Tool
,”
AIAA
Paper No. 2013-0202.
18.
Sanderson
,
T.
,
1988
,
Ice Mechanics, Risk to Offshore Structures
,
Graham & Trotman
,
London
.
19.
Korzhavin
,
K.
,
1971
, “
Action of Ice on Engineering Structures
,” U.S. Army Cold Regions Research and Engineering Laboratory Translation TL260, Hanover, NH.
20.
Michel
,
B.
, and
Toussaint
,
N.
,
1977
, “
Mechanisms and Theory of Indentation of Ice Plates
,”
J. Glaciol.
,
19
(
81
), pp.
285
300
.
21.
Ralston
,
T.
,
1979
, “
Sea Ice Loads
,” Technical Seminar on Alaskan Beaufort Sea Gravel Island Design.
22.
Popko
,
W.
,
Heinonen
,
J.
,
Hetmanczyk
,
S.
, and
Vorpahl
,
F.
,
2012
, “
State-of-the-Art Comparison of Standards in Terms of Dominant Sea Ice Loads for Offshore Wind Turbine Support Structures in the Baltic Sea
,”
22nd International Offshore and Polar Engineering Conference
, pp. 426–433.
23.
Matlock
,
H.
,
Dawkins
,
W.
, and
Panak
,
J.
,
1971
, “
Analytical Model for Ice-Structure Interaction
,”
ASCE J. Eng. Mech.
,
97
(4), pp.
1083
1092
.
24.
Karr
,
D. G.
,
Troesch
,
A. W.
, and
Wingate
,
W. C.
,
1993
, “
Nonlinear Dynamic Response of a Simple Ice-Structure Interaction Model
,”
ASME J. Offshore Mech. Arct. Eng.
,
115
(
4
), pp.
246
252
.
25.
BSI
,
2011
, “
Petroleum and Natural Gas Industries—Arctic Offshore Structures (BS EN ISO 19906:2010)
,” British Standards Institution (BSI), London.
26.
Yue
,
Q.
,
Fengwei
,
G.
, and
Karna
,
T.
,
2009
, “
Dynamic Ice Forces of Slender Vertical Structures Due to Ice Crushing
,”
Cold Reg. Sci. Technol.
,
56
(2–3), pp.
77
83
.
27.
Christensen
,
F. T.
, and
Skourup
,
J.
,
1991
, “
Extreme Ice Properties
,”
J. Cold Reg. Eng.
,
5
(
2
), pp.
51
68
.
28.
Suyuthi
,
A.
,
Leira
,
B. J.
, and
Riska
,
K.
,
2012
, “
Short Term Extreme Statistics of Local Ice Loads on Ship Hulls
,”
Cold Reg. Sci. Technol.
,
130
(82), pp.
130
143
.
29.
Jordaan
,
I.
,
Maes
,
M. A.
,
Brown
,
P. W.
, and
Hermans
,
I. P.
,
1993
, “
Probabilistic Analysis of Local Ice Pressures
,”
ASME J. Offshore Mech. Arct. Eng.
,
115
(
1
), pp.
83
89
.
30.
Kamio
,
Z.
,
Matsushita
,
H.
, and
Strnadel
,
B.
,
2003
, “
Statistical Analysis of Ice Fracture Characteristics
,”
Eng. Fract. Mech.
,
70
(
15
), pp.
2075
2088
.
31.
Leira
,
B.
,
Borsheim
,
L.
,
Espeland
,
O.
, and
Amdahl
,
J.
,
2009
, “
Ice-Load Estimation for a Ship Hull Based on Continuous Response Monitoring
,”
J. Eng. Marit. Environ.
,
223
(4), pp.
529
540
.
32.
Liu
,
X.
,
Gang
,
L.
,
Oberlies
,
R.
, and
Qianjin
,
Y.
,
2009
, “
Research on Short-Term Dynamic Ice Cases for Dynamic Analysis of Ice-Resistant Jacket Platform in the Bohai Gulf
,”
Mar. Struct.
,
22
(
3
), pp.
457
479
.
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