Effect of steam conversion on the cellular structure, Young's modulus and negative Poisson's ratio of closed-cell foam
Autor: | Oliver Duncan, Alana Birch, John Hart, Andrew Alderson, Leon Foster, Tom Allen |
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Jazyk: | angličtina |
Rok vydání: | 2020 |
Předmět: |
010302 applied physics
Materials science Modulus Young's modulus 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics Compression (physics) 01 natural sciences Atomic and Molecular Physics and Optics Pressure vessel Poisson's ratio symbols.namesake Surface-area-to-volume ratio Volume (thermodynamics) Mechanics of Materials 0103 physical sciences Signal Processing Ultimate tensile strength symbols General Materials Science Electrical and Electronic Engineering Composite material 0210 nano-technology Civil and Structural Engineering |
ISSN: | 1361-665X |
Popis: | Open-cell auxetic foams have shown potential for use in sporting and other protective equipment. Previous conversion methods for auxetic closed-cell foam used a bespoke pressure vessel. This work expands upon a recent method, using steam absorption followed by cooling and condensation, to change the cell shape of closed-cell foam to impart a negative Poisson’s ratio. Aiming to present a simple, repeatable conversion method, foam samples (20 × 10 × 100 mm) floating in water-filled (∼20 °C), covered ceramic containers (300 × 200 × 100 mm) were heated in an oven at 105 °C for between 1 and 6.5 hrs. Based on the results for these smaller samples, a larger sample of foam (30 × 100 × 100 mm) was also converted, with a steaming time of 8 hrs. The final volume ratio (original/final volume) increased with heating time, up to a maximum of 4.6. The amount and angle of re-entrant (inward-folding) cell walls increased with the final volume ratio as cells contracted further, as evidenced by micro-computed tomography. Poisson’s ratios, measured using digital image correlation, were as low as −0.3 in tension and −1.1 in compression. The tensile Young’s modulus increased from ∼2 up to ∼6 MPa with the final volume ratio and the compressive Young’s modulus reduced from ∼1.5 MPa for low values of the final volume ratio between one and three and then remained close to 1.5 MPa. |
Databáze: | OpenAIRE |
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