Cheng Xinglei, Xing Jianyu, Liu Ju, et al. STUDY ON NATURAL FREQUENCY OF MONOPILE OFFSHORE WIND TURBINE CONSIDERING LONG TERM CYCLIC DEGRADATION EFFECT[J]. 2025, 46(3): 559-566.
Cheng Xinglei, Xing Jianyu, Liu Ju, et al. STUDY ON NATURAL FREQUENCY OF MONOPILE OFFSHORE WIND TURBINE CONSIDERING LONG TERM CYCLIC DEGRADATION EFFECT[J]. 2025, 46(3): 559-566. DOI: 10.19912/j.0254-0096.tynxb.2023-1777.
STUDY ON NATURAL FREQUENCY OF MONOPILE OFFSHORE WIND TURBINE CONSIDERING LONG TERM CYCLIC DEGRADATION EFFECT
This paper establishes a monopile foundation model for offshore wind turbines using the finite element software ABAQUS
combined with the USEFLD subroutine to calculate soil degradation
and uses a simplified spring model to calculate the natural frequency of the monopile wind turbine system. The effects of the number of cyclic load cycles
the magnitude of cyclic load
and the size of the monopile on the natural frequency of the wind turbine system are discussed. The research results show that the natural frequency of the monopile foundation wind turbine system decreases with the increase in the number of cyclic load cycles. Moreover
the greater the cyclic load level
the more significant the degradation of the wind turbine system’s natural frequency. For the wind turbine size and soil conditions considered in this study
after 107 cycles of cyclic loading
the wind turbine’s natural frequency can decrease to as low as 0.954 times its initial value
but it still remains within the 1P to 3P frequency range. Increasing the monopile length
diameter
and wall thickness can reduce the long-term degradation of the monopile wind turbine system’s natural frequency. Under the condition of the same steel usage
increasing the pile diameter is more effective in mitigating the natural frequency degradation of the wind turbine system compared to increasing the pile length and wall thickness
thus ensuring the stable operation of the wind turbine system. ”
关键词
Keywords
references
CHENG X L, WANG T J, ZHANG J X, et al.Finite element analysis of cyclic lateral responses for large diameter monopiles in clays under different loading patterns[J]. Computers and geotechnics, 2021, 134: 104104.
Det Norske Veritas.Offshore standard: Design of offshore wind turbine structures: DNV-OS-J101[S]. Oslo: DNV, 2013: 9-11.
ANDERSEN L V, VAHDATIRAD M J, SICHANI M T, et al.Natural frequencies of wind turbines on monopile foundations in clayey soils—a probabilistic approach[J]. Computers and geotechnics, 2012, 43: 1-11.
MYERS A T, ARWADE S R, VALAMANESH V, et al.Strength, stiffness, resonance and the design of offshore wind turbine monopiles[J]. Engineering structures, 2015, 100: 332-341.
CARSWELL W, ARWADE S R, DEGROOT D J, et al.Natural frequency degradation and permanent accumulated rotation for offshore wind turbine monopiles in clay[J]. Renewable energy, 2016, 97: 319-330.
ALKHOURY P, ABDUL-HAMID S, REY V, et al.A full three‐dimensional model for the estimation of the natural frequencies of an offshore wind turbine in sand[J]. Wind energy, 2020, 24(7): 669-719.
ALEXANDER N A.Estimating the nonlinear resonant frequency of a single pile in nonlinear soil[J]. Journal of sound and vibration, 2010, 329(8): 1137-1153.
BERALDO H D C, FRANZINI G R. A nonlinear mathematical model for dynamic analyses of a cantilevered beam with a tip-mass under support excitation[J]. Journal of the Brazilian society of mechanical sciences and engineering, 2020, 42(1): 1-14.
ARANY L, BHATTACHARYA S, MACDONALD J H G, et al. Closed form solution of Eigen frequency of monopile supported offshore wind turbines in deeper waters incorporating stiffness of substructure and SSI[J]. Soil dynamics and earthquake engineering, 2016, 83: 18-32.
ARANY L, BHATTACHARYA S, ADHIKARI S, et al.An analytical model to predict the natural frequency of offshore wind turbines on three-spring flexible foundations using two different beam models[J]. Soil dynamics and earthquake engineering, 2015, 74: 40-45.
BOUZID D A, BHATTACHARYA S, OTSMANE L.Assessment of natural frequency of installed offshore wind turbines using nonlinear finite element model considering soil-monopile interaction[J]. Journal of rock mechanics and geotechnical engineering, 2018, 10(2): 141-154.
DARVISHI-ALAMOUTI S, BAHAARI M R, MORADI M.Natural frequency of offshore wind turbines on rigid and flexible monopiles in cohesionless soils with linear stiffness distribution[J]. Applied ocean research, 2017, 68: 91-102.
JALBI S, SHADLOU M, BHATTACHARYA S.Impedance functions for rigid skirted caissons supporting offshore wind turbines[J]. Ocean engineering, 2018, 150: 21-35.
PABLO C.Pile foundations for offshore wind turbines: numerical and experimental investigations on the behaviour under short term and long-term cyclic loading[D]. Berlin: Technische Universität Berlin, 2011.