DEVELOPING CAPABILITIES IN MATERIALS AND MANUFACTURE FOR WIND TURBINE BLADES BY THE APPLICATION OF AN ANHYDRIDE-CURED EPOXY RESIN SYSTEM

Abstract

The increased demand for sustainable energy sources has resulted in a boom for the wind energy industry. The industry therefore wants to manufacture wind turbine blades at higher production rates and for the blades themselves to be more efficient. The project undertaken assessed anhydride-cured epoxy resins alongside a novel manufacturing process, vascular curing, to develop both material and manufacturing capabilities to achieve these goals.

This study initially characterised three anhydride-cured epoxy resins developed by Hitachi Chemical Company Ltd. These resins were shown to offer increased interfacial adhesion to glass fibres over an amine-cured epoxy industry benchmark, with an increase in interfacial shear strength of 24-66% depending on the anhydride.

Preliminary trials on carbon fibre were conducted due to demand for larger blades to increase energy efficiency, this again showed improved performance was attained for the anhydride-cured epoxy resin, with a 34% increase in interlaminar shear strength over the industry benchmark.

Composite wind turbines are currently manufactured using long and low temperature cure cycles to prevent thermal gradients developing in the part which lead to manufacturing defects, ultimately limiting the production rate and incurring manufacturing costs. A proof-of-concept setup to experimentally validate vascular curing for thick composite sections (50 mm) was developed. This novel manufacturing process embedded a secondary heating mechanism within the part. It was shown both experimentally that the embedment of a vascule network reduced the observed peak exotherm on average by 25 °C.

Overall, this work has furthered knowledge of anhydride-cured epoxies and showcased that they could have much wider use, due to the improved interfacial adhesion to both glass and carbon fibres. The vascular cure laboratory-scale setup has been developed and shown exciting preliminary results. With further development both these resins and processing methods could both be integrated into current industrial processes to enable better quality wind turbine blades to be made at higher production rates to meet demand.

Date of Award	21 Jan 2021
Original language	English
Awarding Institution	The University of Bristol
Supervisor	Ian Hamerton (Supervisor) & Carwyn Ward (Supervisor)