Flexural Tests and Associated Study of a Full-Scale 65-kW Wind Turbine Tower

Full-scale static test to failure was conducted on a 21.9-m-long 65-kW wind turbine tower to evaluate the flexural strength and failure mode. The test was conducted in a displacement-control mode. The flexural limit state in the form of local buckling near the tower base was developed. The buckling occurred in the elastic range because of a high diameter-thickness ratio of the section. Although local buckling caused slight strength degradation, the reduction was not very significant and the recorded response showed a good amount of post-buckling ductility. The local buckling flexural strengths predicted from established standards correlated very well with the measured buckling strength. A parametric finite-element analysis was also conducted. By properly modeling the boundary condition and a local dent on the tower wall, a good correlation of the structural response and failure mode was also achieved. It was found that the ultimate strength and failure mode were sensitive to the boundary condition considered in the model. The presence of a local dent would affect both the location and type of local buckling, although the failure load is less sensitive to local dent.