Composite Materials in a Novel Tidal Turbine Design

Abstract

This thesis aims to optimize the design of a tidal turbine, by replacing steel components with composites. Initially all major turbine components such as axle, rotor and stator were considered, but in guidance with supervisor and SmartMotor representative the scope was narrowed down to constructing a carrying composite axle. At the present time this is a component considered to have excess material providing unnecessary high weight. It was informed that the current solution was hastily chosen, as the price of manufacturing a custom hollow steel member would be too costly.The thesis concludes that composite materials are well suited for the application, however not without challenges. Significant weight reduction is obtainable, but further consideration on bearing area is needed to prevent wedging of the sliding bearings when exposed to extreme conditions. A hybrid solution containing the current central axle attached to carrying shafts of composites is considered to be the easiest way of gaining weight loss at low manufacturing costs. Initially tidal stream energy and the working environment of the turbine are described to provide an overview of the technology, in context with the societies climate challenges. Then composites are presented with regards to its features, the relevant production method and failure criteria. The forces acting on the structure is evaluated and simplified to provide relevant loads and boundary conditions. These are then utilized in a digital model constructed in the CAE program Abaqus. Analysis are run and used to investigate and optimize the composite configuration.Results obtained from the analysis are suggestions of fiber orientation, wall thickness and choice of material.