Finite Element Analysis of Transition Piece of Built Foundation and New Wind Turbine Tower

Under the background of rush to install in 2019 and 2020, incidents such as contract breaches and equipment not being delivered on schedule occured from time to time. This paper takes the wind farm in East China as an example, most of the foundation has been poured, but the wind turbine manufacturer cannot deliver the tower and equipment as scheduled, and the owner is forced to choose another wind turbine manufacturer. However, the tower of the new wind turbine manufacturer does not match the interface of the established foundation. The interface of the built tower is larger than the interface of the foundation and cannot be installed directly. The Transition joints between the foundation and the tower has become one of the most important design links. This paper takes a wind turbine tower with a height of 141 m for a 2.4 MW wind turbine as an example. Based on the ABAQUS finite element analysis software, the mechanical performance of the transition joint between the established wind turbine foundation and the replacement tower was analyzed, including extreme conditions and fatigue conditions. The analysis results showed that the total plastic strain is less than 1.0% when the wall thickness of the transition joint steel tube changes within the range of 37-45 mm under the extreme conditions; during the service period of the tower, the cumulative value of the damage at the weld toe of the butt weld between the steel tube and the lower flange is relatively large, and the fatigue conditions control the design. When the wall thickness of the transition joint steel tube changes within the range of 37-45 mm, cumulative fatigue damage of dangerous point decreases while the thickness increase. The cumulative fatigue damage exceeds 1.0 with the thickness 39 mm, and equals 0.66 with the thickness 45 mm. For the safety consideration, the final thickness will be 45 mm. With the transition piece, the bending stiffness of the foundation is 81 GN·m/rad, that can fulfil the minimum 30 GN·m/rad requirements of the wind turbine manufacturer. The wind turbine manufacturer can run safely.