TY - GEN
T1 - Linear modal analysis of a horizontal-axis wind turbine blade
AU - Acar, Gizem
AU - Feeny, Brian F.
N1 - Publisher Copyright:
© The Society for Experimental Mechanics, Inc. 2015.
PY - 2015
Y1 - 2015
N2 - In this work, mode shapes and modal frequencies of a horizontal axis wind turbine blade are found. The blade is modeled as a pre-twisted beam under bend-bend-twist deformations, and the strain, gravitational potential and kinetic energy expressions are found. These expressions are then simplified for linear theory, and further by using the assumed modes method in which assumed modes are chosen independently for flapwise, edgewise, and twist deflections from a cantilevered uniform beam. Lagrange’s equations of motion are applied to the assumed modal coordinates, and coupled linear equations are thus found. Modal analysis is applied to the assumed modal equations to find the resonance frequencies, and the resulting mode shapes are recombined to express the mode shapes in the bend-bend-twist coordinates. The approach was applied to a uniform twisted rectangular beam, and the first three mode shapes are found to be combinations of the inplane and out-of-plane bending. The results of the modal analysis are compared with results from a finite element analysis, and the mode shapes and frequencies are consistent. The method is also applied to NREL’s 5 MW wind turbine blade to find its bend-bend-twist mode shapes and natural frequencies.
AB - In this work, mode shapes and modal frequencies of a horizontal axis wind turbine blade are found. The blade is modeled as a pre-twisted beam under bend-bend-twist deformations, and the strain, gravitational potential and kinetic energy expressions are found. These expressions are then simplified for linear theory, and further by using the assumed modes method in which assumed modes are chosen independently for flapwise, edgewise, and twist deflections from a cantilevered uniform beam. Lagrange’s equations of motion are applied to the assumed modal coordinates, and coupled linear equations are thus found. Modal analysis is applied to the assumed modal equations to find the resonance frequencies, and the resulting mode shapes are recombined to express the mode shapes in the bend-bend-twist coordinates. The approach was applied to a uniform twisted rectangular beam, and the first three mode shapes are found to be combinations of the inplane and out-of-plane bending. The results of the modal analysis are compared with results from a finite element analysis, and the mode shapes and frequencies are consistent. The method is also applied to NREL’s 5 MW wind turbine blade to find its bend-bend-twist mode shapes and natural frequencies.
KW - Assumed modes
KW - Bend-bend-twist coupled vibrations
KW - Finite element analysis
KW - Position dependent modal properties
KW - Wind turbines
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U2 - 10.1007/978-3-319-15048-2_12
DO - 10.1007/978-3-319-15048-2_12
M3 - Conference contribution
AN - SCOPUS:84946032904
T3 - Conference Proceedings of the Society for Experimental Mechanics Series
SP - 125
EP - 131
BT - Experimental and Applied Mechanics - Proceedings of the 2014 Annual Conference on Experimental and Applied Mechanics
A2 - Sottos, Nancy
A2 - Rowlands, Robert
A2 - Dannemann, Kathryn
T2 - 2014 SEM Annual Conference and Exposition on Experimental and Applied Mechanics, 2014
Y2 - 2 June 2014 through 5 June 2014
ER -