Sandia performed an independent hydrostructural analysis of the Ocean Renewable Power Company (ORPC) TidGen® turbine, with a focus on the bolted-joint connections. Sandia’s CACTUS hydrodynamics software was used to predict dynamic loads on the turbine, and these loads served as input to structural dynamics analysis, performed using Abaqus finite-element analysis (FEA) software.
The analysis examined bolt loads with considerations for ultimate and fatigue loading. The bolt hardware was explicitly modeled using beam elements in the FEA model, and bolt loads were processed directly from simulation results. The figure shows the turbine geometry and the location of the analyzed bolts. The fatigue failure analysis predicted that life cycles are well within the design service life of the ORPC TidGen® turbine. Nevertheless, analysis did predict low margins of safety on bolts and loss of preload during extreme operating conditions.
Further analyses are recommended to investigate the benefits of increasing the size of the shaft-end bolts and increasing the preload on the foil-frame bolts.