A STUDY ON REPAIRING PROCEDURES INVOLVED WITH LEADING EDGE CRACKS, OFFSETTING, OVERBITE & UNDERBITE OF GLASS FABRIC REINFORCED COMPOSITE BASED WIND TURBINE BLADES

Abstract

Rotor blades are the most important part of wind turbine system, which are generally made up of polymer matrix based composites. The performance and lifetime of the wind turbine system often depend of the constituent of composite materials, properties of these materials, design of blades and manufacturing techniques. However the inspections after manufacturing of blades do reveal certain defects which need to addressed and fixed before it is sent for real time operations. Further offsetting usually occurs when closure of two blade halves lead to displacement of aerodynamic suction side from the aerodynamic pressure side. This work is concerned with the two main objectives: one is to repair leading edge cracks in the longitudinal direction, outside the area with existing external root over lamination, the second objective is to how offsetting is measured, evaluated and repaired especially in connection with: overbite and underbite. All these repair procedures were conducted on the glass fabric reinforced polyester blades manufactured by Hand lay-up technique. Until aforementioned repair procedures are not performed, the blades will not be sent to assembly stage. Ultrasonic inspection was conducted as per ASTM standards, ASTM E317 and ASTM E1316.