In this paper, a multibody model of wind turbine towers with the consideration of soil -structure interaction (SSI) is proposed to investigate their dynamic responses to seismic excitations in time domain. Using joint beam elements, the elastic tower is discretized into many rigid bodies coupled elastically by constraint joints and springs. The SSI is represented by a frequency-independent discrete parameter model approximately. The governing motion equations are derived by the application of Lagrange formalism including Lagrange multipliers. To investigate the effects of SSI and the dynamic behaviour of wind turbine towers under aerodynamic loading and earthquake loading, the tower of a large wind turbine is modelled and simulated with recorded seismic excitations.

No abstract

No abstract

The paper deals with a generalization of Helmholtz' conditions for the existence of a first‐order kinetic potential related to a given set of 2nd order ordinary differential equations. The extension affects the consideration of such ODE systems which are not self‐adjoint due to dissipation. Necessary and sufficient conditions are given for the simultaneous existence of two state functions – a Lagrangian and a dissipation function – both of the first‐order such that the given set of 2nd order ODE results from the well‐known Lagrangean approach.

No abstract