eprintid: 10196705 rev_number: 11 eprint_status: archive userid: 699 dir: disk0/10/19/67/05 datestamp: 2024-09-09 09:24:25 lastmod: 2024-09-09 09:24:25 status_changed: 2024-09-09 09:24:25 type: article metadata_visibility: show sword_depositor: 699 creators_name: Comitti, Alessandro creators_name: Bosi, Federico title: Thermomechanical characterisation and plane stress linear viscoelastic modelling of ethylene-tetra-fluoroethylene foils ispublished: inpress divisions: UCL divisions: B04 divisions: F45 keywords: Lightweight materials, Membrane structures, Viscoelasticity, Polymers, Time-temperature superposition principle, Thin films note: © 2024 Springer Nature. This article is licensed under a Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/). abstract: Ethylene-tetra-fluoroethylene (ETFE) is a polymer employed in tension membrane structures with mechanical properties that strongly depend on time and temperature effects. A comprehensive understanding of the mutual influence of these variables and a unified viscoelastic constitutive model design can enable wider exploitation of ETFE in sustainable lightweight construction. This study presents a thermomechanical characterisation of ETFE foils through quasi-static tensile experiments spanning two orders of magnitude of strain rates, creep, relaxation, shear and dynamic cyclic tests in a wide range of temperatures suitable for building applications, from -20 Celsius degrees to 60 Celsius degrees. The experimental results in different material orientations are used to identify the limits of the linear viscoelastic domain, define the direction-dependent creep compliance master curves and calibrate the parameters of a plane stress orthotropic linear viscoelastic model, employing the Boltzmann superposition and the time-temperature superposition principles. The model has been numerically implemented using a recursive integration algorithm and its code is provided open source. A validation on independently acquired data shows the accuracy of the constitutive model in predicting ETFE behaviour within the linear viscoelastic regime usually adopted during structural design, with excellent extrapolation capabilities outside the range of the calibration data. date: 2024-08-28 date_type: published publisher: SPRINGER official_url: http://dx.doi.org/10.1007/s11043-024-09704-5 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2310302 doi: 10.1007/s11043-024-09704-5 lyricists_name: Comitti, Alessandro lyricists_id: ACOMI67 actors_name: Comitti, Alessandro actors_id: ACOMI67 actors_role: owner funding_acknowledgements: H2020-MSCA-ITN-2020-LIGHTEN-956547 [European Union] full_text_status: public publication: Mechanics of Time-Dependent Materials pages: 28 citation: Comitti, Alessandro; Bosi, Federico; (2024) Thermomechanical characterisation and plane stress linear viscoelastic modelling of ethylene-tetra-fluoroethylene foils. Mechanics of Time-Dependent Materials 10.1007/s11043-024-09704-5 <https://doi.org/10.1007/s11043-024-09704-5>. (In press). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10196705/3/Comitti_Thermomechanical%20characterisation%20and%20plane%20stress%20linear%20viscoelastic%20modelling%20of%20ethylene-tetra-fluoroethylene%20foils_AOP.pdf