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Mechanical properties of high performance fibers vis-a-vis applications in flexible structural composites.

机译：高性能纤维在柔性结构复合物中的机械性能。

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Some of the critical properties of high performance organic fibers and fiber assemblies have been addressed vis-à-vis their applications in flexible structural composites. These include: tensile properties; mechanical properties under complex modes of deformation; creep at high tensile loads; changes in physical properties due to thermo-mechanical/chemical treatments used in manufacturing of reinforced rubber goods.; The axial elastic modulus of fibers and tautly twisted filament assemblies of high performance organic polymers have been measured along with their crystalline orientation distributions. Based on well established procedures in continuum mechanics of axially symmetric structures, a quantitative relationship has been derived to relate the axial elastic modulus to the second and fourth moment of average crystalline orientation distribution. The latter was determined by X-ray diffraction measurements with yarns. This model, valid for single-phase materials, has been found to provide an excellent fit of data from twisted yams of aromatic polyamide and highly ordered polyethylene fibers, with a wide range of overall crystalline orientation distributions.; An important property of concern in engineering applications of polymeric filament assemblies of high performance organic fibers is creep. In this study, creep deformation data of gel-spun Ultra High Molecular Weight Polyethylne (UHMWPE) Spectra® 1000 yams have been fitted to a model obtained through an empirical mechanical analog of the viscoelastic process. The non-linear viscoelastic model composed of stress-dependent non-linear mechanical analogs qualitatively predicted the creep response to a series of step-loads applied on the UHMWPE yarns.; To understand the mechanical properties of high performance organic fibers under combined bending and extension, a simple pin-test procedure has been employed to characterize fibers and twisted yarns. The results obtained from the test have been interpreted with regard to the mechanisms through which fibers can exhibit superior performance characteristics under such deformation conditions.; An exploratory study of the changes in the mechanical properties of poly(p-phenylene terephthalamide) (PPTA) fibers due to the thermo-mechanical/chemical treatments used in commercial manufacturing of reinforced rubber goods has been conducted. The changes in tensile properties of PPTA yams have been inferred to be due to the process-induced changes in the overall crystalline orientation distribution.
机译：针对高性能有机纤维和纤维组件在柔性结构复合物中的应用，已解决了一些关键特性。这些包括：拉伸性能；复杂变形模式下的机械性能；在高拉伸载荷下蠕变；由于制造增强橡胶制品所使用的热机械/化学处理而导致的物理性能变化；已经测量了高性能有机聚合物的纤维和绷紧的加捻长丝组件的轴向弹性模量，以及它们的晶体取向分布。基于在轴向对称结构的连续力学中已建立的良好程序，已经得出了定量关系，以将轴向弹性模量与平均晶体取向分布的第二和第四矩相关联。后者通过纱线的X射线衍射测量确定。已经发现，该模型对单相材料有效，可以很好地拟合芳族聚酰胺和高度有序聚乙烯纤维的加捻纱的数据，并具有广泛的总体晶体取向分布。高性能有机纤维的聚合物长丝组件在工程应用中值得关注的重要特性是蠕变。在这项研究中，将凝胶纺的超高分子量聚乙烯（UHMWPE）Spectra ® 1000纱的蠕变变形数据拟合到通过粘弹性过程的经验力学模拟获得的模型中。由依赖于应力的非线性机械类似物组成的非线性粘弹性模型定性地预测了施加在UHMWPE纱线上的一系列阶跃载荷的蠕变响应。为了了解高性能有机纤维在组合弯曲和延伸下的机械性能，采用了简单的针测试程序来表征纤维和加捻纱。从测试中获得的结果已被解释为在这种变形条件下纤维可以表现出优异性能特性的机理。对由于增强橡胶制品的商业生产中使用的热机械/化学处理而导致的聚对苯二甲酰对苯二酰胺（PPTA）纤维的机械性能变化进行了探索性研究。据推测，PPTA纱线的拉伸性能发生了变化，这是由于整个晶体取向分布中由过程引起的变化所致。

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