Corrective Solutions for the Shaft with Flange Used for Fixing the Blade on a 5 kW Wind Turbine to Withstand Extreme Weather Conditions

Abstract

The paper presents a case study on the original solution of a flange shaft as part of the root area of a 5 kW wind turbine blade. There were analyzed the causes that led to the shaft breakage under wind loadings in extreme weather conditions, and consequently technical solutions have been searched in order to improve the shaft design making it more reliable as mechanical strength at extreme wind loadings. The flange shaft is a welded subassembly that keeps the blades attached to the rotor hub. The first part of the paper consists in an analysis referring the loading status, the materials used for blade manufacturing, the identification of critical areas where the breaking was initiated and also the causes for which the materials assumed and specified in the technical design and manufacturing technology failed under loading at wind gusts of about 30 m/sec. Based on this preliminary analysis, the second part of the paper presents the technical solutions which were considered in reference to the materials and the improved design concept aiming to provide the right mechanical strength necessary to withstand specific wind loadings in extreme weather conditions.