Wave–Structure Interactions of Flexible Bags with Elastic Tendons: Application to Wave Energy Conversion

Abstract

A new type of wave energy device has recently been proposed with the key component being a flexible air-filled bag, which is constructed such that the fabric is encased by an array of tendons. The behavior of the bag in still water under hydrostatic loading and its dynamic response when subjected to hydrodynamic loading in waves were previously analyzed using a numerical model developed with the assumption of inextensible tendons. In the present work, the model is extended to include the effects of tendon elasticity. The behavior of the bag with tendons of various moduli of elasticity is then compared with that of the bag with inextensible tendons. It is found that adding elasticity to the tendons has a similar effect to that of increasing the air volume connected to the bag, that is, it increases the resonance period of the device. Consequently, a bag with elastic tendons can be made even smaller in size than a bag with inextensible tendons in order to match the same target resonance period.