Tham khảo tài liệu 'fundamental and advanced topics in wind power part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Efficient Modelling of Wind Turbine Foundations 169 Frequency f Hz Fig. 38. Dynamic stiffness coefficient S22 obtained by finite-element-boundary-element the large dots and lumped-parameter models with M 2 ----- M 6 and M 10 ---- . The thin dotted line . indicates the weight function w not in radians and the thick dotted line . indicates the high-frequency solution . the singular part of S22. Frequency f Hz Fig. 39. Dynamic stiffness coefficient S24 obtained by finite-element-boundary-element the large dots and lumped-parameter models with M 2 ----- M 6 and M 10 ---- . The thin dotted line . indicates the weight function w not in radians and the thick dotted line . indicates the high-frequency solution . the singular part of S24. 170 Fundamental and Advanced Topics in Wind Power Frequency f Hz Fig. 40. Dynamic stiffness coefficient S44 obtained by domain-transformation the large dots and lumped-parameter models with M 2 ----- M 6 and M 10 ---- . The thin dotted line . indicates the weight function w not in radians and the thick dotted line . indicates the high-frequency solution . the singular part of S44. 6. Summary This chapter discusses the formulation of computational models that can be used for an efficient analysis of wind turbine foundations. The purpose is to allow the introduction of a foundation model into aero-elastic codes without a dramatic increase in the number of degrees of freedom in the model. This may be of particular interest for the determination of the fatigue life of a wind turbine. After a brief introduction to different types of foundations for wind turbines the particular case of a rigid footing on a layered ground is treated. A formulation based on the so-called domain-transformation method is given and the dynamic stiffness or impedance of the foundation is calculated in the frequency domain. The method relies on an analytical solution for the wave propagation over depth and this provides a much faster evaluation of the response
