平流层浮空器用柔性复合材料的断裂性能

Fracture properties of flexible composites from aerostat

对某浮空器蒙皮用柔性复合材料的撕裂性能和顶破性能进行了实验研究和数值分析。通过不同切口宽度和总宽度试样的撕裂实验,发现撕裂过程为典型的脆性断裂特征,根据线弹性断裂模型对撕裂过程进行数值模拟得到与实验结果一致的断裂过程,通过数值计算得到扩展过程中裂纹尖端的应力强度因子,计算得到的撕裂承载能力随相对切口宽度增加而降低,与实验结果一致。对不同直径试样进行顶破实验,并以断裂应变为裂纹临界扩展的断裂模型进行数值分析,得到顶破模拟结果与实验结果一致:使顶破位置达到相同的断裂应变值,大直径试样需要较大的位移值,失效时圆心位置的应力水平保持不变使得最大顶破承载水平保持不变。

The tearing properties and the punch properties were investigated on the flexible composites from the aerostat by experiments and numerical simulations.For tearing tests of specimens with different quench width and total width,the typical brittle fracture is displayed in the crack propagation process.The tearing fracture process from the numerical simulations with linear fracture model is consistent with the experimental results.With the stress intensity factor calculated,the maximum loading level for the tearing tests reduce with the increment of the quench width ratio which agree well with the experimental results.The FEA simulations with the fracture strain as the crack propagation criteria rebuilt the experimental results of the punch tests.Larger displacement is needed for the specimens with larger diameter to perform the same fracture strain at the punch center while the maximum loading level is the same for different specimens for the stress at the punch center.