基于双轴拉伸试验的飞艇蒙皮材料非线性分析

摘要

Airship envelope fabrics are functional laminated weave composites that behaved rather complicated nonlinear mechanical characteristics.An accurate mechanical model is the base for structural design and numerical analysis.The biaxial tensile tests of airship envelope specimens were carried out at seven tensile stress ratios.On the basis of orthotropic composites theory,the elastic engineering constants were calculated by the method of minimization of the sum of square of the strain residuals and the linear mechanical model was presented.The response surfaces of stress-elastic constants could be generated subsequently and the complete three-order polynomi-als nonlinear mechanical model was finally proposed in terms of stress variable.The numerical simulation of biaxial tensile at seven ratios was proposed and the results are in good agreement with the tests situation on the distributions of stress and the deformations of the slit.The stress-strain curves of simulation were compared with the experimen-tal ones and show good consistency.In this case,the mechanical model is accurate enough for airship structural analysis.%飞艇蒙皮为多功能层压织物材料,力学行为呈现复杂的非线性,合理表征其非线性的力学模型对飞艇结构设计与分析至关重要.本文对飞艇蒙皮材料试件进行了7个应力比双轴拉伸试验,基于正交异性材料模型,采用应变残差平方和最小方法计算弹性常数,建立线性力学模型;根据试验数据建立应力弹性常数响应面,建立以应力为变量的完整三次式非线性力学模型.并根据此力学模型建立飞艇蒙皮材料有限元分析模型,通过数值模拟七种应力比下的双轴拉伸试验,分析结果的应力分布和分缝位移与试验现象一致.将分析得到的应力-应变曲线与试验结果进行对比,两者能很好的吻合,表明非线性力学模型及分析方法适用于飞艇结构分析.