Experimental Study On Material Properties And Double-Layer Cushion Of ETFE Foil

Although ETFE was invented in 1972 and widely used in the field of medication, sanitation, etc., it was until 1994 that ETFE film was applied in the field of civil membrane structures. Due to its lightweight, transparency, good self-cleaning, durability and architectural expressive force, ETFE film can substitute glass to become an ideal kind of clading material. Furthermore, as fairly big size and agile geometry can be realized through ETFE air cushion cells, ETFE foil has developed rapidly in Europe over the last decade. However, comprehensive researches on material properties and double-layer cushion structure of ETFE foil are relatively absent both domestically and overseas, and there is no experimental study about double-layer ETFE foil cushion structure under low temperature. Then, the problems aforementioned have been discussed and investigated in this paper.This paper takes the material properties of ETFE foils under different temperature Environment and the mechanical behavior and performance of double-layer ETFE cushion under low temperature Environment as the main research contents. With the specialized software of lightweight structure analysis Easy, the numerial calculation analysis, the material properties and the model test have been employed to carry out deeply research on the design method for ETFE foil structures, the material properties of ETFE foils under different temperature Environment and the structural characters of double layer ETFE foil cushion under low temperature Environment.Based on the experimental study in Europe, the design method for ETFE foil structures is recommended. This paper introduces properties ETFE foil and material properties. And summarizes structural design basis and safety criteria, the aim of that is to compare the different design concepts and find a minimum level of safety criteria to be used. Modelling and analysis of single layer ETFE foil structures and double layer ETFE foil cushion is introduced. Power failure, monitoring of inflation units and quality three issues must be adverted in air supporting system and control. Manufacturing and installation of ETFE foil include material, welding technics, welding seam strength and testing, packing. Functional issues and solutions are advanced. Uniaxial tensile tests of ETFE foils are described in this paper. The specimens are cut from foil along the machine direction (MD) and transverse direction (TD). From the tast results, it is found that the tensile properties of the foils along the MD and TD are almost the same. Different tensile speeds are used in the tests, the aim of that is to study the effect of different tensile speeds. Normal material and transverse welding two kinds samples are used in uniaxial tensile tests of ETFE foils with dumb-bell shape under different temperature environment. In order to find the teamwork between ETFE foil and strain gauge, tests of ETFE foil sliver samples with strain gauge are done.In order to study the structural behaviors of ETFE foil cushion under low temperature environment, the experiment set-up was developed, which mainly consists of loading simulation, environment simulation, ETFE cushion, and automation control and measure system. Loading simulation was carried out through loading simulation chamber (LSC), which can simulate wind suction and pressure about 20 kPa by blowing air into LSC or ventilating air out from LSC. Environment simulation was conducted in environmental simulation chamber (ESC), which can reach -65?C ~+100?C, and hold about 2.0mx1.8x2.2m structure. Planar 1.5m by 1.5m dimension ETFE cushion of 0.188m rise was designed and manufactured for experiments. A special automation control was developed to control the ETFE internal pressure precisely and LSC loading simulation. The 3D scanner (CCD), strain gauge and displacement device were employed to measure the form and strain of ETFE cushion experiencing loading. The experiments have been carried out successfully for ETFE cushion in 25?C, 0?C, -25?C and -50?C, respectively. The ETFE cushion experiences from normal load to final broken load to get the ultimate capacity and broken style. The results unveil some important characteristics of ETFE cushion, which are valuable to ETFE cushion development and application in cold area.