飞艇用层压织物膜材料在双向应力作用下的弹性参数分析

Analysis of Elastic Parameters for Laminated Fabrics Used in Airships Under Biaxial Stresses

为揭示双向应力作用下飞艇用层压织物膜材料弹性参数的响应特征,针对高性能蒙皮材料Uretek3216LV~进行了一系列双轴拉伸试验,获得了9种应力比例条件下的应力-应变关系数据,并分析了其非线性及正交异性特征;采用膜材料试验标准计算了膜材料的弹性参数,分析了应力比及应力比组合对弹性参数的影响规律;运用Matlab软件进行数值分析,得出应力空间的弹性参数响应曲面特征,并提出应力空间弹性参数加权平均值的计算方法,研究了在不同应力水平及应力比下弹性参数的变化规律.结果表明:层压膜材料的弹性参数之间无耦合关系,正交互补性质在其本构关系上的适用性不足;膜材料的变形特征及弹性参数受应力比及应力比组合的影响显著,且均呈现出明显的非线性及正交异性特征;在飞艇结构设计中,宜根据膜材料所属结构部件的应力比分布特征,选取包含相应应力比的组合项来求取弹性参数,以提高弹性参数计算的稳定性和可靠性.

In order to reveal the response characteristics of elastic parameters for laminated fabric used in airships under biaxial stress loading, a series of biaxial tensile tests were first conducted on high perform- ance envelope materials Uretek3216LV . The stress-strain data of nine stress ratios were obtained, and their nonlinear and orthotropic behaviors were analyzed. According to the testing method for elastic con- stants of membrane materials, the elastic parameters of the studied material were then calculated and the effects of the stress ratio and stress ratio combination on theses parameters were discussed. Finally, using the Matlab program, the response characteristics of elastic parameters in plane stress space were obtained and analyzed, and a weighting method was proposed to calculate the elastic parameters and to achieve the influences of the stress levels and stress ratios. Results indicate that there is no coupling relation between these parameters, and then the reciprocal relationship may not apply to constitutive model of laminated fabrics. The mechanical behaviors of the studied material are affected by the stress ratios and stress ratio combinations significantly, and obvious linearity and orthotropy can be observed for different stress levels and stress ratios. Therefore, during the real design practice of airship structures, for a steady reliable cal- culation of elastic parameters it might be more seasonable to use determination options whose stress ratios are determined by specific stress distributions of structural member.