建筑膜材料双轴向拉伸弹性常数的估算方法

以机织物增强建筑膜材料为对象,研究了通过单轴向拉伸试验来获取双轴向拉伸弹性常数的方法。根据膜材料双轴向拉伸弹性模量的确定方法,以二维正交各向异性材料的本构关系为基础,以膜材料经纬向拉伸应力比为设定加载参数,导出了机织膜材料单轴向和双轴向拉伸弹性模量之间的关系,提出了采用单轴向拉伸弹性常数估算建筑膜材料双轴向拉伸弹性常数的方法。通过参考文献中对GF/PTFE和PVDF1202T膜材料拉伸试验的测试结果,验证研究所提出方法的适用性。结果表明,在工程实践中利用单轴向拉伸试验来获得膜材料双轴向拉伸弹性模量是可行的。

ESTIMATION OF THE ELASTIC CONSTANTS OF ARCHITECTURAL MEMBRANE UNDER BI-AXIAL TENSILE LOADING

Elastic constants obtained from uni-axial tensile tests are frequently used to represent elastic properties of architectural membranes reinforced by woven fabrics. However, it has generally been accepted that the elastic constants from bi-axial tensile tests are more applicable in the design of architectural membrane structures. The purpose of this study is to develop a method to estimate bi-axial elastic constants of architectural membrane material by using uni-axial tensile tests. General method for obtaining bi-axial tensile modulus of membrane materials is first presented to show the influences of loading conditions. Then, based on the constitutive equations for 2-dimensional orthotropic material and by taking the loading ratios in warp and weft directions as loading parameters in bi-axial stress-strain tests, a model is developed to build a relationships between the elastic constants of membrane materials reinforced by woven fabrics under both uni-axial and bi-axial tensile loading. Finally, testing data of typical architectural membrane materials obtained from literature, GF/PTFE, and PVDF1202T are used to verify the model. Good agreements have been illustrated to validate the proposed method.