摘要:
为了研究含初始裂纹蒙皮薄膜的抗撕裂行为, 选用Kevlar纤维增强的具有预制初始裂纹切口(PIC)的平流层飞艇用蒙皮薄膜, 采用弹塑性断裂力学平面应力分析方法, 考虑经纬向纱束之间的滑移摩擦效应, 分析了薄膜裂纹尖端的撕裂强度与变形形式, 建立了裂纹尖端撕裂物理模型和基于摩擦效应修正的等差法拉伸变形计算模型, 获得了裂纹尖端应力集中区的应力分布。为验证计算模型的合理性, 分别对PIC长度为10、 20、 30及40 mm的试样进行了撕裂强度试验。结果表明: 当PIC宽度比率不超过0.50时, 模型计算值与试验值的误差小于4.12%;与改进的应力强度因子法相比, 所建计算模型具有更高的计算精度, 为平流层飞艇蒙皮撕裂强度的设计提供了一种有效的方法。
Abstract:
In order to investigate the anti-tearing behaviors of envelop thin films with initial cracks, Kevlar fabric reinforced envelope thin films used in stratospheric airships with prefabricated initial crack (PIC) were chosen and the plane stress analysis method of elastic-plastic fracture mechanics was adopted. Considering the effects of slipping friction between warp and weft, the tearing strength and deformation modes of film crack tips were analyzed. Physical model of crack tip tearing and arithmetical tensile deformation computational model based on friction effects were established. The stress distribution of stress concentration area among crack tip was obtained. In order to verify the rationality of the computational model above, specimens with PIC length of 10, 20, 30 and 40 mm were tested to obtain the tearing strength, respectively. Results show that when PIC width ratio does not exceed 0.50, the deviation between calculated values of models and testing values is lower than 4.12%. Compared with the improved stress intensity factor theory, the computational model established above is more accurate, which provides an effective approach for the tearing strength design of stratospheric airship envelope.
百度学术
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