Uniaxial cyclic tensile mechanical properties of ethylene tetrafluoroethylene (ETFE) foils

• Uniaxial cyclic tensile mechanical properties are investigated under eight loading cases.
• Elastic modulus divided into three parts explains deformation discrepancy of ETFE foil structure.
• Yield point is determined by the elastic modulus of 70 MPa to minimize strain difference.
• Ratcheting strain and hysteresis loop area at the 16th cycle are found to be approximate stable.
• Obtained values are useful for analyzing structural stress, deformation and energy dissipation.

This paper concerns the uniaxial cyclic tensile mechanical properties of ethylene tetrafluoroethylene (ETFE) foils that are widely used in mechanical and construction industries. The experiments involved eight cases with loading stress amplitudes ranging from 4 to 21 MPa. The experimental results show that the yield stress is a main mechanical property as the hysteresis loop and ratcheting strains become noticeable after the yield stress and that the elastic modulus, hysteresis loop and ratcheting strains evolve with the number of cycles and loading stress amplitude. To quantify these mechanical properties, a newly-developed MATLAB program is employed to process the experimental data. It is found that the appropriate cyclic elastic modulus needs to be divided into three kinds and that ratcheting strains and hysteresis loop area in the 16th cycle are found to be approximate stable. These findings could offer an understanding of the discrepancies between numerical results calculated based on the uniaxial mechanical properties and experimental results under field loading conditions.

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