Volume-Change-Driven Strain Analysis for Foldable Origami Structures of Wave Energy Harvester: A Coordinate-Based Material-Matching Framework

Rapidly rising global electricity demand and stringent decarbonisation targets have intensified the search for untapped zero-carbon resources. Ocean wave energy, theoretically exceeding 2 TW, remains largely unexploited because conventional rigid Wave Energy Converters (WECs) perform poorly in mild seas and require wide spectral bandwidths. This study explores an ultra-lightweight, foldable origami-inspired shell that replaces massive resonant structures with compliant polymer facets whose geometry can be tuned in real time. A critical design challenge is selecting an elastomer for the flexible quadrilateral BMPN region that links rigid faces without fracture or excessive damping. We derive a closed-form expression for the distance between vertices B and P as a single-valued function of the global folding angle , validated experimentally to within 4.4 %. Five cases are then analysed to determine the maximum required tensile strain, yielding a range of 0.3111.647. Matching these mechanical demands against a candidate database identifies foamed plastics, soft metals, common polymers, elastomers, and thermoplastic elastomers as optimal choices that combine low mass, recyclability, and fatigue resistance. The framework offers designers a quantitative route to fully collapsible, reliable origami WECs and provides a foundation for future experimental validation and hydrodynamic efficiency optimisation. This work delivers a lightweight, foldable origami wave-energy design to slash costs and speed deployment.