平流层飞艇蒙皮承力层撕裂性能的多尺度渐进损伤分析

The load-bearing layer of Stratospheric Airship envelop is a flexible composite material, which is mostly composed of plain weave reinforcement fiber and coated hyperelastic matrix. Tear property is important performance parameter of the load-bearing layer. At present the load-bearing layer multi-scale analysis ,only built a level of microscopic single-cell model , but no more in-depth study interphase of fiber and matrix, so that result in a large deviation between the experimental and numerical simulation. To solve the problem of the inadequate microscopic analysis on the load-bearing layer of the envelop structure and the large difference between experimental and numerical simulation, this project uses the micro, meso and macro-unity, theoretical and experimental combination of methods to building a micro, meso, macro-coupled multi-scale model. Fully considering the effect of the interphase, accurately characterizing of the physical constants of the interphase, in-depthly studying transfer mechanism of stress, strain, displacement, damage and other information in the multi-scale model, for the development of multi-scales analysis methods. On the basis of the previous, building the meso mechanics model of fiber breakage, matrix crack, interface debonding, it will make a unified progressive damage analysis the multi-scale model, revealing the tear failure mechanism of the load-bearing layer, which establish multi-scales and multi-levels analysis method for the load-bearing layer. The results of this study provide the basis for the design and manufacturing of load-bearing layer of Stratospheric Airship envelop, a reliable and effective method for the characterization and evaluation of the tear property of the flexible composite material, all of which promote the development of China's Stratospheric Airship.

平流层飞艇蒙皮承力层是柔性复合材料，多采用增强纤维平纹编织和超弹性基体涂层制成，撕裂是其重要的性能指标。现有的承力层多尺度分析，只建立了一个层次的细观单胞模型，而没有更加深入地研究纤维和基体间的界面相，使实验和数值模拟的偏差较大。本项目针对承力层在细观分析上的不足，实验与数值模拟的差别大，采用微观、细观与宏观相统一、理论与试验相结合的方法，建立微观、细观、宏观相耦合的多尺度模型，充分考虑界面相的影响，准确表征界面相的物理常数，深入研究应力、应变、位移、损伤等信息在三种尺度模型中的传递机制，发展多尺度分析方法，建立微观下纤维断裂、基体破裂、界面脱粘的力学模型，对多尺度模型进行统一的渐进损伤分析，揭示承力层撕裂的失效机理，建立承力层撕裂的多尺度、多层次分析方法。研究成果为平流层飞艇蒙皮承力层的设计、制造提供依据，为柔性复合材料的撕裂性能表征和评价提供可靠、有效的方法，促进我国平流层飞艇的研制。

涂层纤维织物柔性复合材料由聚合物纤维织物及聚合物涂层构成，不仅拥有良好的力学性能，还具有耐腐蚀、耐冲击等优异的特点，可作为浮空器的蒙皮材料。相较刚性复合材料，柔性蒙皮材料在使用过程中不可避免地受到拉伸及撕裂载荷，为了充分发挥蒙皮材料的应用潜能，从细观尺度出发研究柔性蒙皮材料的拉伸及撕裂性能具有重要意义。.为获取细观模型的力学参数和结构参数，参照相关试验标准分别进行了纱线拉伸实验、蒙皮材料拉伸实验、蒙皮材料撕裂实验。基于实验数据及蒙皮材料细观图像建立涂层平纹织物柔性复合材料有限元单胞模型。.为验证模型的有效性，分别采用该模型、离散单胞模型、连续介质模型进行拉伸破坏的数值模拟。比较结果认为，有限元单胞模型能够反映出实际材料的细观结构，并且能够较为准确地预测出材料的断裂强度及断裂伸长率，为研究材料的撕裂性能提供理论依据。.基于有限元单胞模型，在有限元软件中建立涂层平纹织物柔性复合材料撕裂模型，通过适当前处理进行撕裂破坏的数值模拟，得到的撕裂曲线与撕裂实验曲线能够较好吻合，纱线断裂所造成的曲线震荡较为明显，从细观角度揭示柔性蒙皮材料的撕裂机理，为蒙皮材料的止裂设计提供依据。