Proceedings of the IASS-SLTE 2014 Symposium “Shells, Membranes and Spatial Structures: Footprints” 15 to 19 September 2014, Brasilia, Brazil Reyolando M.L.R.F. BRASIL and Ruy M.O. PAULETTI (eds.) Numerical simulation of burst-test of an ETFE membrane Marianna Coelho * , Deane Roehl a and Kai-Uwe Bletzinger b * Departamento de Engenharia Civil Universidade do Estado de Santa Catarina Rua Paulo Malschitzki, s/n, 89219-710, Joinville, Santa Catarina, Brazil a Instituto Tecgraf and Departamento de Engenharia Civil Pontifcia Universidade Catlica do Rio de janeiro Rua Marques de So Vicente 225, 22453-900, Rio de Janeiro, Brazil b Lehrstuhl fuer Statik Technische Universitaet Muenchen Arcisstrasse 21, D-80333 Muenchen, Germany Abstract This work presents a numerical model for the simulation of the behavior of pneumatic structures made of ETFE material. The model is applied to the simulation of a Burst-test for which experimental measurements are available. In the experiment, samples of ETFE-foil were fixed in a bubble inflation test device between an aluminium plate and an aluminium ring. Air was injected between the plate and the foil, resulting in a spherical deformed configuration. This test is modeled with finite elements and the numerical models are compared to experimental results. The elastoplastic material model with von Mises yield criteria is considered in the numerical analysis. Small strain and large strain were adopted for comparison. The results obtained with the numerical analysis with large strains are in accordance with the experimental results. On the other hand the results of the numerical analysis with small strains are valid only in the first steps of the analysis. These results reinforce the importance of considering a material model with large strains to model this type of material and suggest the use of von Mises plasticity for ETFE-foils. Keywords: inflated membranes, membrane materials, finite element method, NURBS surfaces 1. Introduction ETFE(Ethylene tetrafluoroethylene) is a polymer classified as a semi-crystalline thermoplastic. This type of polymer is more resistant to solvents and other chemicals than others. Ethylene tetrafluoroethylene consists of monomers of Ethylene (C2H4) and Tetrafluorethylene (C2F4 ). When these monomers are submitted to moderate temperature, pressure, and in presence of a catalyst, it polymerizes: In 1970 ETFE was produced for the first time by DuPONT with the name Tefzel . The features of Tefzel are described in the Properties Handbook [4]. According to Robinson-Gayle et ali. [9], ETFE was first used as roofing material in a zoo building in Burgers Zoo, Arnheim in the Netherlands in 1981. It was subsequently been used in various buildings predominantly in the United Kingdom and Germany. The low weight of ETFE is one of the most important features that motivates the use of this material in structural buildings. Moreover, it has been used more often on roofs, resulting in a lower cost for the foundation. The translucent property is advantageous, because it allows the utilization of natural light, reducing the energy consumption. Another property related to resource consumption and commented by Robinson-Gayle et ali. [9] is the anti-adhesive nature of ETFE. This property means that roofs and atria need to be cleaned less frequently reducing maintenance cost. The recycling potencial is other characteristic that is important in days of sustainability. Robinson-Gayle [9] relates that once the material is clean it can be recycled by heating it to its softening temperature. The softening temperature of ETFE is low so this is not a very costly operation, the recycled ETFE can be added into the hopper with virgin ETFE. Copyright © 2014 by the authors. Published by the International Association for Shell and Spatial Structures (IASS) with permission. 1