StingRAY Structural Optimization Final Technical Report

Abstract

The overall project objective is to materially decrease the leveled cost of energy (LCOE) of the Columbia Power (CPower) StingRAY utility-scale wave energy converter (WEC). This will be achieved by reducing structural material and manufacturing costs and increasing energy output. In this Project, improving the overall Power-to-Weight ratio (PWR) is accomplished through lowering design margins?allowing for weight reduction and more efficient, cost-effective WEC manufacturing and assembly?and by optimizing mass-related WEC performance parameters, such as center of gravity and system inertia.

A mixed materials approach to further structural optimization was developed under this Project and validated with extensive laboratory structural testing. This approach substitutes fiber-reinforced plastic (FRP) for steel where appropriate. The benefits of steel are maintained where most useful, for instance at structural joints where the stiffness of steel is required, and the complex geometry is more readily fabricated with steel. However, there are structural spans whose simple shapes are readily fabricated with mandrel-wound FRP and where significant cost and weight savings can be found. An adhesive, double lap shear joint is used to join the FRP and steel subcomponents.