Numerical analysis of structured sheet material in flexible oscillating water column wave energy converter

To improve the power output and reduce the stress levels for Flexible Wave Energy Converters (FlexWECs), a structured material using a sheet of natural rubber with a specific pattern called NR937 is developed in this research. Mechanical characterisation tests are conducted to determine the material properties, and the YEOH hyper-elastic model is employed to capture the nonlinear behaviour of this material. Fluid-structure interaction simulations are performed for a FlexWEC using a CFD-FEA tool. The responses of the Poly-A-OWC model equipped with both the innovative NR937 material and a conventional sheet of Natural Rubber (NR) are compared, and the deformation of flexible membrane, stress distribution, flow field, and power output are all fully explored. The results indicate that at resonance, the deformation amplitude of the flexible membrane using NR937 is increased by 1.3 times compared to that using NR, while the maximum stress increases by only 12%. Additionally, the peak power output of the Oscillating Water Column (OWC) Wave Energy Converter (WEC) utilizing NR937 is approximately 2.6 times higher than that of the WEC using NR. This suggests that structured sheet materials possess potential for improving the performance of FlexWECs, including increasing power output, reducing stress levels in flexible membrane and extending the service life.