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首页> 外文学位 >Effect of geometric parameters on the in-plane crushing behavior of honeycombs and honeycombs with facesheets.
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Effect of geometric parameters on the in-plane crushing behavior of honeycombs and honeycombs with facesheets.

机译：几何参数对蜂窝和带面板蜂窝的面内破碎行为的影响。

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摘要

In aerospace field, use of honeycombs in energy absorbing applications is a very attractive concept since they are relatively low weight structures and their crushing behavior satisfies the requirements of ideal energy absorbing applications. This dissertation is about the utilization of honeycomb crushing in energy absorbing applications and maximizing their specific energy absorption (SEA) capacity by modifying their geometry. In-plane direction crushing of honeycombs is investigated with the help of simulations conducted with ABAQUS. Due to the nonlinearity of the problem an optimization technique could not be implemented; however, the results of the trend studies lead to geometries with improved SEA.;This study has two objectives; the first is to obtain modified cell geometry for a hexagonal honeycomb cell in order to provide higher energy absorption for minimum weight relative to the regular hexagonal cell geometry which has 30° cell angle and walls at equal length. The results of the first objective show that by increasing the cell angle, increasing wall thickness and reducing vertical wall length it is possible to increase the SEA 4.8 times; where the honeycomb with modified geometry provided 3.3 kJ/kg SEA and with regular geometry 0.68 kJ/kg SEA.;The second objective considers integration of the energy absorbing honeycombs into the helicopter subfloor, possibly as the web section of a keel beam. In-plane direction crushing of a honeycomb core sandwiched between two facesheets is simulated. Effects of core and facesheet geometric parameters on the energy absorption are investigated, and modified geometries are suggested. For the sandwich structure with thin facesheets increasing cell angle, increasing wall thicknesses and decreasing the cell depth increase the SEA. For the ones with thick facesheet reducing vertical wall length, increasing wall thicknesses and reducing the cell depth increase the SEA. The results show that regular honeycomb geometry with thin facesheets has SEA of 7.24 kJ/kg and with thick facesheets 13.16 kJ/kg. When the geometries are modified the SEA increases to 20.5 kJ/kg for the core with thin facesheets and 53.47 kJ/kg for the core with thick facesheets.;The key finding of the dissertation is that the in-plane direction crushing of the honeycombs with facesheets has great potential to be used for the energy absorbing applications since their SEA levels are high enough to make them attractive for applications where high crash loads need to be absorbed such as helicopter crash.
机译：在航空航天领域，蜂窝在能量吸收应用中的使用是非常有吸引力的概念，因为它们是相对轻的结构，并且其破碎性能满足理想的能量吸收应用的要求。本文主要研究蜂窝破碎在能量吸收应用中的应用，并通过改变其几何形状来最大化其比能量吸收（SEA）能力。借助ABAQUS进行的模拟研究了蜂窝的面内方向挤压。由于问题的非线性，因此无法实施优化技术。但是，趋势研究的结果导致SEA有所改善的几何形状。第一个方法是获得六角形蜂窝单元的修改后的单元几何形状，以便相对于具有30°单元角和等长壁的常规六角形单元几何结构，以最小的重量提供更高的能量吸收。第一个目标的结果表明，通过增加泡孔角度，增加壁厚和减小垂直壁长，可以将SEA增加4.8倍；其中，几何形状经过修改的蜂窝提供了3.3 kJ / kg的SEA，规则几何结构的蜂窝提供了0.68 kJ / kg的SEA。模拟了夹在两个面板之间的蜂窝状芯的面内方向挤压。研究了核心和面板几何参数对能量吸收的影响，并提出了修改后的几何形状。对于具有薄面板的夹层结构，增加单元角，增加壁厚和减小单元深度会增加SEA。对于具有较厚面板的面板，可减小垂直壁长度，增加壁厚度并减小单元深度会增加SEA。结果表明，具有薄面板的规则蜂窝几何结构的SEA为7.24 kJ / kg，厚面板为13.16 kJ / kg。修改几何形状后，薄面板芯的SEA会提高到20.5 kJ / kg，厚面板芯的SEA会提高到53.47 kJ / kg。面板具有巨大的潜力，可用于能量吸收应用，因为它们的SEA水平足够高，从而使其对于需要吸收高碰撞载荷的应用（例如直升机坠毁）具有吸引力。

著录项

  • 作者

    Atli-Veltin, Bilim.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Engineering Aerospace.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 193 p.
  • 总页数 193
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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