Application of a new two dimensional nonlinear tuned mass damper in bi-directional vibration mitigation of wind turbine blades

A new two-dimensional non-linear tuned mass damper inerter (2d-NTMDI) is proposed in the present paper with the aim of suppressing bi-directional vibrations. The proposed 2d-NTMDI includes a single mass and two sets of springs, dashpots and inerters configured in two axes. With respect to the displacements in two axes, the resulting restoring forces have nonlinear characteristics. While the proposed novel 2d-NTMDI has the capability of mitigating bi-directional vibrations simultaneously, the nonlinearity of the system makes the optimization a challenging task. The particle swarm optimization (PSO) algorithm is adopted to obtain the optimum design parameters of the 2d-NTMDI. To evaluate the effectiveness, the proposed 2d-NTMDI is deployed in a 5MW-wind turbine blade suffering from bi-directional vibrations in the edgewise and flapwise directions. Therefore, an analytic model of a wind turbine blade with a 2d-NTMDI is derived. The aerodynamic loading is computed using blade element momentum theory. The effectiveness of the 2d-NTMDI is tested under different loading conditions. Also, the fatigue damage of the wind turbine blades is calculated according to the rain-flow cycle counting approach and Miner's law. It is concluded that the optimized design 2d-NTMDI can prolong the blade fatigue life by 24.6%.