Effects of Localized Manufacturing-induced Defects in Wind Turbine Blades

摘要

Localized manufacturing-induced defects can compromise the overall structural behavior ofwind turbine blades, including compressive strength and fatigue life. While much research hasbeen pursued on the effects of defects, there is still a need for empirical models that can assist inunderstanding the relationship between defect geometries and their effects on blade durability. Theobjective of this current research is to develop an empirical model that can be used to estimate theimpact that a local high-porosity defect will have on the fatigue performance of a typical fiberglassreinforced wind turbine blade. Flat plates are manufactured using a variety of specially designedprocessing conditions with the intent of directing the flow to induce defect regions in compositeplates that span the range from high- to low-porosity densities. The plates are cut into slices, andthe slices examined using optical microscopy, SEM and CT-scanning techniques. A set of couponsis tested in flexure to assist in the design of the size of specimens to be used for fatigue testing.Future work is to conduct a fatigue test program to develop an empirical model that relates thenumber of cycles to failure to the state of stress and the degree and depth of porosity.