The Study On The Mechanical Properties Of Architectural Membrane Materials

With the development and wide application of membrane structures, people pay more and more attention on architectural membrane materials which consider as a new type of building materials. People also focus on the mechanical properties because of its worldwide application. Architectural membrane materials in membrane structures are mainly constitute of substrate, coating and surface layer. Substrate always are glass fabric and polyester fabric, while the coating is a polyvinyl chloride (PVC) and polytetrafluoroethylene (PTFE). The fabric is general plain weave, which is simple, and be most widely used. Based on PVC and PVDF architectural membrane material, the paper do more research on the tensile, tear and creep properties respectively. Primary research contents and results are as follows:1. The tensile properties under different standard, tensile properties of the different materials and orthotropic behavior of tensile properties were studied. The results showed that: it has the largest tensile strength and breaking elongation under standard ASTM 4851, while minimum under standard JIS-L1096, and other centred; the material of FLUOTOP?T2 1002 has better isotropy than that produced in native; membrane materials were classical orthotropic materials, and the theory of Elasticity for Orthotropic Plates was suitable for the modulus of the material.2. The tear properties and mechanisms of membrane materials under different standards were studied, especially the influence of the crack length and direction on its tearing strength and strain under mono-axial centre slit tear test. It discovered that: the mechanisms of double tongue tear test is more complicated than that of the trapezoidal tear test, it was the deformation of vertical yarn, and the shear, tensile and binding force acting on the transverse yarn, and destruction at las, while the trapezoidal tear test was the propagation of tear triangle; the length and direction of initial crack has a great influence on tear properties, which decrease linear with the length and more and more slowly with the increase of angle, two failure modes (brutal and progressive) depend on the effective length of the crack, and brutal mode occurred on the small length while progressive on the other.3. We also studied the creep properties and the orthotropic of the material and its tensile properties under recovery completely. And the result showed that: the creep properties depending on the load level and time, and it can be describe by function of time logarithm; the tensile properties before and after creep had great difference in final stage, modules of the stage increase with the increase of load level; the creep properties also showed orthotropic and describe by time logarithm, the creep resistant properties of off-axis direction were much more worse than that of weft and warp direction, and 45°direction was the worst.