PVC膜材剪切模量非线性研究及有限元分析

Nonlinear study and finite element analysis of shear modulus of PVC coated fabrics

基于气承式膜结构顶部受不同水平荷载时位移呈非线性变化这一现象,从膜材剪切特性入手,通过双轴偏伸试验研究膜材剪切性能,得出膜材剪切应力与剪切模量的变化关系,发现膜材剪切模量并非常数。为验证这一结论,引入ABAQUS有限元分析,依据试验中得到的膜材剪切模量与剪切应力关系建立材料模型,以气承式膜结构为例进行分析。在考虑膜材剪切特性基础上,通过模拟得到的气承式膜结构顶部水平荷载-位移曲线也呈非线性趋势,剪切模量为常数条件下模拟位移与试验位移误差率均值在20%左右,而膜材剪切模量随剪切应力变化条件下模拟位移与试验位移的误差率在10%左右。验证了膜材剪切模量不为常数这一假设,表明膜材剪切模量变化对气承式膜结构位移变形的影响不能被忽略。

In this paper,based on the phenomenon that the displacement of the top of the air-supported membrane structure is nonlinear when subjected to different horizontal loads,the shear performance of the membrane material was studied from the shear characteristics of the coated fabrics through biaxial tensile shear test,and the relationship between the shear stress and the shear modulus of the coated fabrics is obtained,it was found that the shear modulus of the membrane material is not a constant.In order to verify this conclusion,ABAQUS finite element analysis was introduced in this paper,and a material model was established according to the relationship between shear modulus and shear stress of the coated fabrics obtained in the test.The air-supported membrane structure is used as an sample for analysis.On the basis of considering the shear characteristics of the membrane material,the horizontal load displacement curve at the top of the air supported membrane structure obtained through simulation also shows a non-linear trend.The error rate between the simulated displacement with a constant shear modulus and the experimental data is about 20%,while the error rate of the simulated displacement with a constant shear modulus of the membrane material changing with shear stress remains around 10%.The hypothesis that the shear modulus of the membrane is not constant is verified,indicating that the influence of the change of the shear modulus on the displacement and deformation of the gas-supported membrane structure cannot be ignored.