Contribution of fluid viscous dampers on fatigue life of lattice-type offshore wind turbines

Abstract

Given the recent developments in wind energy generation technology, offshore wind turbines have been widely used to exploit offshore wind energy. Supporting structures of offshore wind turbines play an important role in correct operation of wind turbines and their operational life. Supporting structures will experience millions of lateral load reversals due to wave- and wind-induced vibrations. Because of the stress concentration, more fatigue damages are expected at the structural joints. Supporting structures of offshore wind turbines have commonly small inherent damping and it is believed that because additional viscous damping can reduce structural vibrations and result in less stress concentration at the joints. In this study, vertically oriented fluid viscous dampers are used to increase fatigue life of a full-height Lattice-type Offshore Wind Turbine (LOWT). Obtained results indicated that the use of fluid viscous dampers significantly delayed fatigue failure and increased fatigue life of structural joints by up to 3 times.