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Localized temperature rise as a novel indication in damage and failure behavior of biaxial non-crimp fabric reinforced polymer composite subjected to impulsive compression
Aerospace Science and Technology ( IF 5.6 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.ast.2020.105885
Zhongxiang Pan , Zhenyu Wu , Jie Xiong

Non-crimp fabric reinforced polymer (NCFRP) composite is a suitable choice as structure material in aerospace use. One of the most important issues related to adiabatic failure is the correlation among temperature elevation, adiabatic shear band and failures of the material. In this study, impulsive damage and failure modes with temperature rise in biaxial NCFRP composite specimens were investigated under increased strain rates from 200/s to 2500/s. Path and distribution of temperature rise were experimentally characterized when the composite was subjected to in-plane and out-plane impulsive compression. It is found that (i) localized temperature can rise above a hundred degrees Celsius, reaching or even exceeding the Tg of the resin matrix and polyester tricot in specimen, which causes stress concentration and subsequent failure in warp/weft fiber tows in localized positions. (ii) For the out-of-plane compression, the localized temperature rise indicates dispersed inter-layer shear deformation in the biaxial NCFRP composite by stress wave mismatch effect. With the increase of strain rate, intensive temperature rise is a good announcement for an adiabatic shear band quickly and thoroughly splitting the specimen. (iii) For the in-plane compression, slight impact loading triggers small debonding and cracking along warp/weft fiber tows or at the fiber-matrix interface by fiber tows microbuckling effect. With the increase of strain rate, the localized temperature rise reveals that single shear band is developed and further evolved into zigzag shear bands, while catastrophic delamination failure is the dominant mode at higher strain rate. Higher temperature values at kinking positions are caused by fiber tows buckling-fold effect. Thermal degradation effect imperils the polymeric matrix and tricot around the kinking positions where bridging cracking, obstructing the spread of adiabatic shear band, and leading to the pull-out/breakage/splitting damages of warp/weft fiber tows. (iv) This work indicates that high-speed thermographic technology is an important method for investigating the dynamic behavior of composite materials. Localized temperature rise is an effective indicator in complex correlation with the multiple physical interaction including the adiabatic shear band, matrix/tricot softening, fiber tows kinking, localized damages and failures.



中文翻译:

局部温度升高是双轴非卷曲织物增强聚合物复合材料受到脉冲压缩的破坏和破坏行为的新指示

非卷曲织物增强聚合物(NCFRP)复合材料是航空航天中用作结构材料的合适选择。与绝热破坏有关的最重要的问题之一是温度升高,绝热剪切带和材料破坏之间的相关性。在这项研究中,研究了在应变速率从200 / s增加到2500 / s的情况下,双轴NCFRP复合材料试样随温度升高的脉冲破坏和破坏模式。当复合材料受到面内和面外脉冲压缩时,通过实验表征了温升的路径和分布。发现(i)局部温度可以升高到一百摄氏度以上,达到甚至超过T g样品中树脂基体和聚酯经编纱的位置,这会导致应力集中以及局部位置的经/纬纤维丝束的破坏。(ii)对于面外压缩,局部温度升高表明双轴NCFRP复合材料由于应力波失配效应而分散了层间剪切变形。随着应变率的增加,强烈的温度升高是绝热剪切带迅速而彻底地分裂试样的一个好消息。(iii)对于面内压缩,轻微的冲击载荷会通过纤维束微屈曲效应沿经/纬纤维束或在纤维-基质界面处引起小的剥离和破裂。随着应变率的增加,局部温度升高表明单剪切带得以发展,并进一步演变为之字形剪切带,在高应变率下,灾难性分层失败是主要模式。扭结位置的较高温度值是由纤维束的屈曲褶皱效应引起的。热降解效应使聚合物基体和经编织物在扭结位置周围发生弯曲开裂,阻碍了绝热剪切带的扩散,并导致经/纬纤维丝束的拉出/断裂/裂口损坏。(iv)这项工作表明,高速热成像技术是研究复合材料动态行为的重要方法。局部温度升高是与多种物理相互作用(包括绝热剪切带,基质/细线软化,纤维束扭结,局部损伤和破坏)复杂相关的有效指标。

更新日期:2020-06-01
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