Wind-induced Dynamic Response And Stability Performance Research Of Inner Stiffened Wind Turbine Tower

Modern Mega-Watt graded large horizontal axis wind turbine tower approach 120 meters high, weighing about 50% of the total weight of the whole machine, and the thickness of the shell only account for less than 1% of its diameter, will support the entire weight of the wind turbines up components as well as the nature of all kinds of complicated dynamic alternating loads, if the tower losing dynamic instability or suffering strength failure, it tend to be a devastating losses of the whole wind turbine system even worse.In this paper, mainly aims at the instability and damaging phenomenon of the tower, put forward a kind of inner-stiffened reinforcement form of the tower structure, in order to improve the tower’s safety. So make a research with different inner-stiffened form of the tower(considering different axial and circumferential numbers, different reinforced rib size and shell thickness changes), calculating the tower strength in different static load conditions and the nonlinear behavior, buckling stability, the modal analysis of the whole turbine system as well as dynamic response. At the same time, make a co MParison with the unstiffened tower.Through static strength and dynamic response calculation result, it shows that the inner-stiffened tower can improve the lateral stiffness and reduce the response under dynamic loading, besides, the stiffened ribs reinforcement played a role in anti collapsion effects to some extent. But the reinforcement setting is needed to be optimized selection, The number of stiffened ribs reinforcement does not perform in direct proportion with the effects, some factors needed to be considered, such as a reasonable configuration of rib size, the total amount of steel controlling(economic effectiveness), stress(stress ratio) and shell thickness etc.Through nonlinear analysis of the tower the results shows that: the performance of the material nonlinearity and geometric nonlinearity is not obvious from the initial stage of load apply to the proportional limit, the load displacement curve of material elastic and elastic-plastic situation basically coincide. With the load increasing until the tower material yield, showing obvious double nonlinear behavior. In addition, consider flange contact can simulate the true performance of the stress distribution of flange and bolt connection. Another numerical simulation was carried out on the initial installation of the inclined tower, shows that different initial inclination of bearing capacity does not have much i MPact on the tower itself when do not consider other defects, mainly manifested in the load displacement curves are the curves move left-to-right, same inclination of the situation differentia mainly lies in the forward inclination curve more quick rise than backward to reaching the peak,and horizontal displacement smaller than the backward inclination.The buckling stability of inner stiffened tower analysis showed that: reinforced tower performs different whole or local buckling instability mode from the unreinforced, mainly because of the rib plays an important role to produce a restraint effect on the reinforcement grid interval, besides the number and the size of reinforced ribs and the thickness of the tower can influence the stability of the tower.