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Dynamic thermomechanical behavior of polymers and polymeric matrix composites.

机译:聚合物和聚合物基复合材料的动态热力学行为。

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摘要

The thermomechanical behavior of polymer and polymeric matrix unidirectional fiber reinforced composite materials subjected to dynamic impact loading is investigated in this study. Compression and tension Split Hopkinson Bars (SHBs) coupled with a 16-element high speed HgCdTe infrared detector array were used to measure in real time the variation of stress, strain and temperature under a range of strain rates (400--4000/s) in the impact loaded materials.; A significant temperature rise was observed in both compression and tension tests for the unidirectional composite material. Combined results from temperature measurements and stress-strain curves indicate that this temperature is mainly due to damage of the material. To identify the damage mechanism that makes the primary contribution to this heating effect, similar studies on pure polymers as well as the interaction between fiber and matrix (fiber pushout) were performed.; Different thermomechanical response was observed in three polymers tested, PMMA, polycarbonate and EPON 862. By correlating temperature-strain and stress-strain curves, it was found that while for PMMA and EPON 862 significant temperature rise was generated by damage, for PC it was mainly due to plastic work. It was also found that for PC the fraction of plastic work converted into heat was much smaller than that of metals. (0.5 as opposed to ∼0.9).; Study of the interaction between fiber and matrix was conducted through single fiber pushout tests on a modified SHB device. The pushout force and displacement were measured, along with frictional heating generated from the fiber/matrix relative sliding. Experimental results were compared with two dimensional axisymmetric dynamic finite element simulations of the entire SHB and loading anvils. The effects of impact speed, property mismatch between fiber and matrix, fiber surface roughness, and normal confining pressure were investigated. It was found that the response of dynamic fiber pushout was different from that of static case.
机译:本研究研究了聚合物和聚合物基单向纤维增强复合材料在动态冲击载荷作用下的热力学行为。压缩和拉力霍普金森棒(SHB)结合16元素高速HgCdTe红外探测器阵列用于实时测量在一定应变速率(400--4000 / s)下的应力,应变和温度变化在冲击载荷物料中。在单向复合材料的压缩和拉伸测试中均观察到明显的温度升高。温度测量和应力-应变曲线的综合结果表明,该温度主要是由于材料损坏所致。为了确定对该加热效果起主要作用的破坏机理,对纯聚合物以及纤维与基体之间的相互作用(纤维推出)进行了类似的研究。在三种测试的聚合物(PMMA,聚碳酸酯和EPON 862)中观察到了不同的热机械响应。通过关联温度-应变曲线和应力-应变曲线,发现对于PMMA和EPON 862,由于损坏而产生了明显的温升,而对于PC,则是主要是由于塑料加工。还发现,对于PC,塑性功转换成热量的比例远小于金属。 (0.5相对于〜0.9)。通过在改良的SHB设备上进行单根光纤推出测试,研究了光纤与基质之间的相互作用。测量推出力和位移,以及纤维/基质相对滑动产生的摩擦热。将实验结果与整个SHB和加载砧座的二维轴对称动态有限元模拟进行了比较。研究了冲击速度,纤维与基体之间的性能不匹配,纤维表面粗糙度和正常围压的影响。发现动态光纤推出的响应与静态情况不同。

著录项

  • 作者

    Li, Zhouhua.;

  • 作者单位

    University of Delaware.;

  • 授予单位 University of Delaware.;
  • 学科 Applied Mechanics.; Engineering Mechanical.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 应用力学;机械、仪表工业;工程材料学;
  • 关键词

  • 入库时间 2022-08-17 11:47:34

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