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Shear thickening fluids for enhanced protection from micrometeoroids and orbital debris.

机译：剪切增稠液可增强对微流星体和轨道碎片的防护。

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摘要

In October 2015, after the discovery of liquid water on the surface of Mars, NASA declared that the coming decades will see a renewed push to establish "a sustainable human presence beyond Earth, not just to visit but to stay". A challenge for deep-space missions to Mars and beyond will be the construction of space vehicles, habitats, and extra-vehicular activity (EVA) suits capable of withstanding the threats from micrometeoroids and orbital debris (MMOD). MMOD particles, while typically small in size, travel at extraordinary velocities in low-earth orbit (LEO)---on the order of 1-15 km/s (~2,200-33,000 mph)---rendering them highly energetic and dangerous to exposed astronauts performing EVAs.;This dissertation explores using a novel soft body armor technology that intercalates colloidal shear thickening fluids (STFs) into protective textiles, i.e., STF-ArmorT(TM), to improve the resistance of EVA suits to hypervelocity MMOD threats. STF-Armor(TM) has previously been demonstrated to improve resistance to puncture, ballistic, and shock threats--all elements inherent to MMOD projectiles. Under the terrestrial testing conditions explored in this dissertation, incorporation of STF-Armor(TM) into the EVA suit significantly enhanced the resistance to puncture threats and increased specific energy absorption when the projectile was traveling at velocities sufficiently high enough to induce fragmentation upon impact. These results demonstrate proof-of-concept and advance the Technology Readiness Level (TRL) of STF-Armor(TM) to the point where the next step of technology validation will take place in the actual LEO environment on the exterior of the International Space Station.;The intended application motivates some fundamental questions about the effect of confinement on the measured deviatoric stress---the shear stress and the first and second normal stress differences---within the underlying colloidal dispersion. Improved experimental measurements of these viscometric functions were obtained via controlled-stress rheometry. The magnitude and scaling of the viscometric functions were found to be consistent with expectations from Stokesian Dynamics simulations, Dissipative Particle Dynamics simulations, and theory that properly accounts for hydrodynamic interactions between particles at high shear rates. In STF-Armor(TM), concentrated colloidal dispersions are confined to micron-sized gaps between yarn fibrils, a degree of confinement not accessible with current rheometry techniques. A novel experimental approach was developed to study the effects of extreme confinement on the measured deviatoric stress, where the colloidal dispersion was confined not between the plates of a rheometer tooling, but rather between the surfaces of large, non-deformable non-Brownian particles at high packing fractions. At high shear rates, confinement was found to lead to stronger shear thickening and enhanced normal stress differences. Ultimately, the findings of this dissertation help to advance fundamental understanding of the flow behavior of suspensions consisting of both colloidal and non-Brownian particles, which has broad and far-reaching value for applications beyond the soft body armor technology considered here.
机译：2015年10月，在火星表面发现液态水后，美国宇航局宣布，未来几十年将再次推动建立“在地球以外的可持续人类生存之路，不仅是参观，而且是停留”。进行火星及其他深空任务的挑战将是建造能够抵御微流星体和轨道碎片（MMOD）威胁的太空飞行器，栖息地和车外活动（EVA）服。 MMOD粒子虽然通常很小，但是却以极高的速度在低地球轨道（LEO）中传播，速度大约为1-15 km / s（〜2,200-33,000 mph），这使它们具有很高的能量和危险性本文将探索使用一种新颖的防弹衣技术，该技术将胶体剪切增稠液（STF）插入保护性纺织品STF-ArmorT（TM）中，以提高EVA服对超高速MMOD威胁的抵抗力。先前已证明STF-Armor（TM）可以提高抗穿刺，弹道和电击威胁的能力-MMOD弹丸固有的所有元素。在本文探索的地面测试条件下，将STF-Armor™掺入EVA服中时，当弹丸以足够高的速度行进，足以引起撞击时碎裂时，可显着增强对穿刺威胁的抵抗力，并增加比能吸收。这些结果证明了概念验证，并将STF-Armor™的技术准备水平（TRL）提升到了下一步，技术验证的下一步将在国际空间站外部的实际LEO环境中进行预期的应用引发了一些基本的问题，即限制作用在潜在的胶体分散体中对测得的偏应力（剪切应力以及第一和第二法向应力差）的影响。通过控制应力流变法获得了这些粘度函数的改进实验测量结果。发现粘度函数的大小和比例与Stokesian动力学模拟，耗散粒子动力学模拟以及在高剪切速率下适当考虑粒子之间的流体动力学相互作用的理论相符。在STF-Armor TM中，浓缩的胶态分散体被限制在纱线原纤维之间的微米级间隙中，这是当前流变技术无法达到的限制程度。开发了一种新颖的实验方法来研究极限约束对所测得的偏向应力的影响，其中胶体分散不局限于流变仪工具的板之间，而是局限于大的，不可变形的非布朗粒子的表面之间。高包装率。在高剪切速率下，发现限制会导致更强的剪切增稠和增大的法向应力差。归根结底，本论文的发现有助于增进对由胶体和非布朗粒子组成的悬浮液流动特性的基本理解，对于此处所考虑的防弹衣技术以外的应用具有广泛而深远的价值。

著录项

  • 作者

    Cwalina, Colin D.;

  • 作者单位

    University of Delaware.;

  • 授予单位 University of Delaware.;
  • 学科 Chemical engineering.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 345 p.
  • 总页数 345
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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