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Mechanical degradation of thermal properties of flexible aerogel blankets.

机译：柔性气凝胶毯的热性能的机械降解。

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摘要

Aerogel materials are of significant interest to numerous applications in many areas of engineering such as oil, gas, aerospace, military, construction, building and apparel because they offer insulating properties that outperform traditional materials by a factor ranging from 2 to 8. Although an aerogel can be manufactured in a clamshell, sleeve or sheet shapes, the most versatile form is a blanket. Aerogel blankets are composites of silica aerogel particles dispersed in a reinforcing fiber matrix that turns the brittle aerogel into a durable and flexible insulating mat.;While aerogel blankets exhibit excellent thermal properties, they are still some concerns over dust mitigation when the blankets are flexed and deformed. The generation of dust is important because it can lead to a degradation of the insulating properties and is not ideal for the work environment during installation for some applications during subsequent uses. In this study, various experimental investigations such as thermal analysis, three-point bending tests and tensile tests have been performed to characterize the thermal insulation properties and degradation level of several commercially-available flexible aerogel blanket materials. The results are reported and discussed in this study. The microstructure of these aerogel blankets are also investigated for better understanding of the failure process. Knowledge of the thermal and mechanical properties are important for the optimization of the design for these heteregeneous materials.;Usage of insulating aerogel blankets in thermal protection systems and heat-sensitive environments, such as infrared suppression around engine and hot components applications, leads to accurate predictions of their thermal properties such as their effective thermal conductivity in such applications. As part of this study, simple theoretical and numerical models have been developed to predict the effective thermal conductivity of flexible aerogel blankets, which consist of fibers, aerogel particles and air-pockets. The theoretical models are thermal conductivity models as a function of aerogel, air-pocket and fiber volume fractions. In the numerical study, the effective thermal conductivity of the aerogel composites is computed with different aerogel particles to fiber volume ratios using the finite element method. The numerical analysis of thermal conductivity is conducted by generating 3D models of the microstructure of the aerogel blanket.;Interesting predictions concerning the effects of air-pocket and aerogel particles volume fractions are observed. For low aerogel particles content (less than 10%), the results of the theoretical and the numerical models show good agreement but discrepancies are observed at high aerogel particles content.
机译：气凝胶材料在石油，天然气，航空航天，军事，建筑，建筑和服装等许多工程领域的许多应用中都引起了人们的极大兴趣，因为它们提供的绝缘性能比传统材料要高2到8倍。可以制成翻盖，袖子或片状形状，最通用的形式是毯子。气凝胶毯是分散在增强纤维基质中的二氧化硅气凝胶颗粒的复合材料，可将脆性气凝胶转变为耐用且柔软的隔热垫。虽然气凝胶毯表现出出色的热性能，但它们在弯曲和收缩时仍需要缓解灰尘变形了。灰尘的产生很重要，因为它会导致绝缘性能下降，并且对于后续使用中某些应用的安装过程中的工作环境不是理想的。在这项研究中，已经进行了各种实验研究，例如热分析，三点弯曲试验和拉伸试验，以表征几种市售柔性气凝胶毯材料的隔热性能和降解水平。在这项研究中报告并讨论了结果。还对这些气凝胶毯的微观结构进行了研究，以更好地了解破坏过程。对热和机械性能的了解对于优化这些非均质材料的设计很重要。;在热保护系统和热敏感环境中使用绝缘气凝胶毯，例如在发动机和热部件应用周围的红外抑制，可确保精确预测其热性能，例如在此类应用中的有效热导率。作为这项研究的一部分，已经开发了简单的理论和数值模型来预测由纤维，气凝胶颗粒和气袋组成的柔性气凝胶毯的有效导热系数。理论模型是作为气凝胶，气穴和纤维体积分数的函数的热导率模型。在数值研究中，使用有限元方法计算了不同气凝胶颗粒与纤维体积比时气凝胶复合材料的有效导热系数。通过生成气凝胶毯的微观结构的3D模型进行热导率的数值分析;观察到有关气穴和气凝胶颗粒体积分数影响的有趣预测。对于低气凝胶颗粒含量（小于10％），理论模型和数值模型的结果显示出很好的一致性，但是在高气凝胶颗粒含量下观察到差异。

著录项

  • 作者

    Gnahore, Brice G.;

  • 作者单位

    West Virginia University.;

  • 授予单位 West Virginia University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 194 p.
  • 总页数 194
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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