Static and Fatigue Analysis of A Small Wind Turbine Blade
Abstract
Small wind turbine blades are subjected to fatigue due to continuous variations in the wind speed and wind direction which leads to failure, without serving the design life of 20 years. Hence, it is important to test the small wind turbine blades for static and fatigue strength before placing them into operation. This research paper presents the results of static test experiments conducted on a blade of 1.5 m length made of glass fiber reinforced plastic. During the experiments, six strain gauges are mounted at distances of 0.375, 0.750 and 1.125 m from the blade root on the upper and lower surface and induced stresses are calculated from the strains recorded in 0.5 (equivalent to 60 m/s wind speed), 1, 1.5 and 2 kN. This blade was also tested for the completely reversed amplitude of 100 mm at the 8 Hz frequency to study the fatigue behaviour using computational software FEMFAT designed for fatigue analysis and a dedicated experimental setup developed in the laboratory. The static stresses induced in the blade are found at considerably lower than the permissible limit. The fatigue damage and life results obtained through FEMFAT also indicate the expected reliability and safe design life. This is also confirmed through the experimental test carried out for 1.6 × 107 cycles.
