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IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints


IASS Symposium 2014

SESSION: General 10: ETFE - Design and Experiments

Biaxial creep tests of ETFE foil

< Table of Contents for General 10: ETFE - Design and Experiments
  • Proceedings Name: IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints
  • ISSN: (Electronic Version) 2518-6582
  • Session: General 10: ETFE - Design and Experiments
  • Title: Biaxial creep tests of ETFE foil
  • Author(s): Yintang LI, Minger WU, Hao WANG
  • Keywords: ETFE foil, biaxial creep test, bubble test, biaxial reduction factor, numerical simulation
Abstract
Recent decades have witnessed a widely application of ETFE foil in spatial structures, such as botanical gardens and stadiums. In membrane structural design, mechanical property of this material is one of key issues, which has attracted numerous researchers’ interests. While ETFE foil creeps in long-term biaxial tension in structures, prior researches of its creep behavior were on the basis of uniaxial creep tests. This paper focuses on biaxial creep tests of ETFE foil and its numerical simulation. Two biaxial creep tests of ETFE foil in cruciform shape were performed for 24 hours. In these creep tests, stress ratio of the machine direction to the transverse direction was set as 1:1 and stress was at identical 6 MPa. These tests showed biaxial creep displacements were overestimated using merely uniaxial creep coefficients, counting one third as those in uniaxial tests. Hence, to establish a link between uniaxial and biaxial creep coefficients, biaxial reduction factor was introduced to consider this decline. Simulation results indicated this approach was practicable to determine biaxial creep coefficients. Meanwhile, a bubble creep test was performed for 10 hours. Stress in the circular specimen was generated by inner pressure 1845 Pa and ranging from 5.8 MPa to 8.5 MPa. Creep displacements of two points were monitored by laser sensors. Creep behavior of this test was simulated by FEM software package ANSYS. In numerical simulation, biaxial reduction factor and linear interpolation were applied to determine creep coefficients at the maximum stress. Simulation results showed good agreement with test data at both monitored points. Combining advantages of each biaxial test, this paper determined and verified biaxial creep property of ETFE foil.

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