抄録
A floating offshore wind tubine using spar platform as the floating foundation is considered here. It is known that a spar platform may show Mathiew instability in its dynamic motions. This is because the equations of motions in heave and pitch directions couple each other, and the equation of motion in pitch direction reduces to Mathiew equation in its approximated form.
In this paper, we propose a stability diagram of the parametric excitation for a spar platform, where the effects of damping and wave elevation are both considered. Then, the applicability of the derived stability diagram is validated by numerical examples using a spar platform model, where the upper part of the spar has a reduced diameter. Some design guidelines concerning the ratio of pitch/heave natural periods are also given.
