Based on the theories of Euler-Bernoulli and Timoshenko beams,and considering the characteristics of variable section towers and soil-structure interaction,both a comprehensive model with coupling springs and a fixed model were established.The differ-ential transform method(DTM)was employed to calculate the transverse vibration equation of the variable section beam of offshore wind turbines(OWTs),and MATLAB software was used to solve for the fundamental frequency.The validity and accuracy of this method were verified by comparison with measured results.Additionally,the effects of tower height,taper ratio,and spring stiffness on the fundamental frequency were further analyzed.The research results indicate that the fundamental frequency is highly sensitive to changes in tower height;specifically,a decrease in tower height results in a significant decrease in fundamental frequency.As the taper ratio of the variable section beam decreases,the bottom diameter of the tower increases,leading to an improvement in the fundamental frequency.When considering the spring foundation system,the fundamental frequency increases with any increase in spring stiffness.Moreover,among the three-spring model components,the coupling spring has the greatest influence on the fundamental frequency.
关键词
Timoshenko梁/Euler-Bernoulli梁/海上风机/系统基频/大直径单桩
Key words
Timoshenko beam/Euler-Bernoulli beam/Offshore wind turbines/System fundamental frequency/Large diamet-er monopile
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