乙烯-四氟乙烯薄膜单轴拉伸中心撕裂力学行为

Uniaxial tensile central tearing behaviors of ethylene tetrafluoroethylene foils

  • 摘要: 针对乙烯-四氟乙烯(ETFE)薄膜结构膜面存在因初始缺陷、飞致物刺穿等引发膜材撕裂而导致结构承载力衰减和破坏的安全性问题,结合数字图像相关(DIC)技术对ETFE薄膜进行了系列单轴中心撕裂试验,深入分析了切缝长度、切缝角度和切口样式对薄膜撕裂力学行为的影响。结果表明:ETFE薄膜的典型撕裂过程呈现出4个特征状态;局部缺陷会显著影响薄膜的面外屈曲和破坏形态;典型撕裂抗力-位移曲线可分为撕裂前段、撕裂抗力上升阶段和撕裂后段3个阶段;薄膜的极限撕裂强度随切缝长度的增大而减小,随切缝角度的增大而增大;切口样式使薄膜在完全破坏时表现出类脆性或类延性破坏特征;“一”形切缝和直角边缘切口易引发应力集中,导致薄膜承载性能的显著衰减。所得结论可为ETFE薄膜的撕裂力学性能研究和ETFE膜结构的安全性评估提供有益参考。

     

    Abstract: Aiming at the safety of ethylene tetrafluoroethylene (ETFE) foil structural membrane surface, which is caused by initial defects and puncture of flying objects, leading to the attenuation of structural bearing capacity and damage, a series of uniaxial central tearing tests were carried out on ETFE foils combined with the digital image correlation (DIC) technology, and the effects of slit length, slit angle and notch shape on the tearing mechanical behaviors of the foils were analyzed in depth. The results show that the typical tearing propagation process of ETFE foils exhibits four characteristic states. Local defects can significantly affect the locations of the out-of-plane warping and the failure modes of the foils. The typical tearing strength-displacement curve can be divided into three characteristic phases: the pre-tearing phase, the tearing resistance rising phase, and the post-tearing phase. The ultimate tearing strength of the foils decreases with the increase of slit length and increases with the increase of slit angle. The notch shapes cause the foils to exhibit brittle-like or ductile-like damage characteristics upon complete damage. The “one” shaped slit and the right-angle edge notch tend to cause stress concentration, leading to significant degradation of the foil's load-bearing properties. The conclusions obtained can provide useful references for the study of the tearing mechanical properties of ETFE foils and the safety assessment of ETFE membrane structures.

     

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