Dynamic Characteristics Analysis And Welding Multi-axial Fatigue Life Prediction Of Large Wind Turbine Tower

As an important component of the wind turbine,the tower drum’s dynamic response and fatigue property directly affect the safe and reliable operation of the wind turbine.With the increase of unit capacity,the blade’s size and the tower drum’s height are gradually increased,and the vibration,stability and working years of the tower drum are put forward higher requirements.So in this paper,the modal analysis,buckling stability analysis and multi axial fatigue life prediction of a 2.0MWs conical tower drum are carried out.Based on describing research status at home and abroad about the analysis of the modal,the buckling and the welded joint’s multi axial fatigue strength,the main contents of this paper are presented.The tower drum structure’s finite element model was established in the ANSYS Workbench,analysed front the 12 step free mode in two case of considering the top quality and not considering the tower top quality and based on fluid-solid coupling’s tower prestressed modal,results showed that the cabin at the top of the tower drum and the blade quality had great influence on modal frequency,its physical properties and the tower structure is the main factor affecting its natural frequency,through calculation and comparison,found that the tower drum’s natural frequency could avoid the rotation frequency of the 1P and 2P times,meeted the above 10% safety margin requirements,namely wind turbine resonance will not occur.As a highly sensitive defect structure,the tower drum bottom’s opening shape had a great influence on the buckling behavior,It was simulated in the extreme conditions of rectangular openings and arc openings,unreinforced frame and reinforced frames are buckling arc openings tower structure analysis showed that the arc was a rectangular doorway doorway buckling performance better;strengthen the frame could improve the buckling strength of the tower structure.Based on the finite element mode lwas established and the tower,the stress distribution under the limit condition of the tower and weld were calculated to analyze the static strength;to meet the requirements of the static strength under the premise of the critical plane method,combined with the specification of GL2010 welding of S-N curves and Miner linear damage rule in fatigue the analysis software Fe-safe for multiaxial fatigue cumulative damage of tower and weld calculation,meet the requirements of the design life of 20 years,the most dangerous position and weld were at the weld toe.