Multiaxial Strain Analysis in Large Wind Turbine Blades under Full-scale Fatigue Testing.

In most full-scale fatigue tests of wind turbine blades, only longitudinal strains are considered in the calculation of damage, while the effects of transverse and tangential strains are ignored, which will lead to varied damage inflicted on different parts of the blade. To analyze this problem, this paper conducted uniaxial and biaxial fatigue tests on a 52.5-meter wind turbine blade and recorded the strain response at each cross section. The test results show that transverse and tangential strains are greater than longitudinal strains in some cross sections of the blade. Then, a cross section of the blade was modeled and simulated using ABAQUS to analyze the strain relationships at other locations on the blade. The strain response at different locations on the blade was also examined, and the simulation results showed that both the transverse and longitudinal strain values for this cross section varied significantly. In addition, the multiaxial strain varies greatly with different loading methods. The strain pattern in the trailing edge panel region is very complex. Therefore, the damage calculation and life prediction of the blade should consider the effect of multiaxial strain, which provides a powerful reference for the subsequent improvement of the multiaxial fatigue damage calculation method and the design of the fatigue test program for large wind turbine blades. [ABSTRACT FROM AUTHOR]