浮空器蒙皮力学行为分析及本构建模

Mechanical behavior of aerostat envelope and constitutive modeling

为了满足承载及特殊的环境适应性需求,在临近空间服役的浮空器囊体蒙皮由高性能纤维织物、阻氦层、耐候层、粘接层等构成。由于囊体充压水平直接决定了浮空器的承载能力,因此有必要建立能够对蒙皮等效力学行为进行准确预测的本构模型,为浮空器强度和寿命设计奠定基础。考虑到蒙皮由多组分材料构成,通过试验分析了纤维织物和功能层对蒙皮等效力学性能的协同影响。根据试验研究结果,发展了能够描述蒙皮各向异性、非线性力学行为的等效本构模型,预测了蒙皮在正轴和偏轴拉伸过程中其宏观应力、纱线剪切角、试样截面收缩率的变化规律。浮空器蒙皮的本构模拟与试验结果取得了较好的吻合,二者相结合揭示了蒙皮宏观力学响应与微结构变形之间的联系。

To meet the requirements of load-bearing and special environmental adaptability,the envelope of near-space operational aerostats consists of multiple layers,such as high-performance fiber fabrics,helium barrier layers,weather layers,and adhesive layers.Since the internal pressure inside the envelope directly determines load-bearing capacity of the aerostat,it is necessary to develop a reliable constitutive model to predict the equivalent mechanical properties of the envelope,which therefore,lays the foundation for strength and life evaluations of the airship.Effects of fiber fabrics and functional layers on the equivalent mechanical properties of the envelope were investigated by experimental characterizations.Based on experimental results,an equivalent constitutive model was developed to study the anisotropic and nonlinear mechanical behavior of the envelope.For both uniaxial and off-axis tensile conditions,predictions on the effective stress,yarn shear angle and specimen cross-sectional contraction agree well with experimental results.The combined experimental and numerical studies have led to insightful understanding between the overall mechanical response and microstructure deformation of the envelope.