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首页> 外文学位 >Two New Approaches to Toughness Characterization of Polyethylene - Case Studies on Low-Density Polyethylene and Ultra-High-Molecular-Weight Polyethylene.
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Two New Approaches to Toughness Characterization of Polyethylene - Case Studies on Low-Density Polyethylene and Ultra-High-Molecular-Weight Polyethylene.

机译：聚乙烯韧性表征的两种新方法-以低密度聚乙烯和超高分子量聚乙烯为例。

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摘要

A new mechanistic approach is applied to characterizing toughness of low-density polyethylene (LDPE) in ductile fracture, introduced in double-edge-notched tensile (DENT) test. Three mechanisms were involved in the new approach, i.e. fracture surface formation, necking and shear plastic deformation. This is different from the original essential work of fracture (EWF) method, as the latter does not consider the shear plastic deformation. The specific energy density for the fracture surface formation, determined from the new approach, was found to be about 12% higher than that from the original EWF method, and the specific energy density for necking is close to that determined from simple tensile test. The closeness of specific energy density for necking between DENT and simple tensile tests provides some support to validity of the new approach in characterizing fracture behavior of polyethylene when accompanied by large plastic deformation and necking. Ultra-high-molecular-weight polyethylene (UHMWPE) was also characterized using DENT test. However, it was found that its fracture behavior cannot be described using the original EWF method, and since necking does not occur, nor by the new mechanistic approach. As a result, a modified EWF method was developed. To justify validity of the modified EWF method, a formulation of energy balance equation was established, from which a nonlinear trend line was used to determine the fracture toughness. This study indicates that the original EWF method cannot be used to deal with the involvement of a significant amount of plastic deformation involved in the fracture process, for characterizing fracture behavior of UHMWPE.
机译：一种新的机械方法被应用于表征韧性断裂中低密度聚乙烯（LDPE）的韧性，并在双边缘缺口拉伸（DENT）测试中引入了这种方法。新方法涉及三种机制，即断裂表面形成，颈缩和剪切塑性变形。这与原始的基本断裂工作（EWF）方法不同，因为后者未考虑剪切塑性变形。发现通过新方法确定的断裂表面形成的比能量密度比原始EWF方法的高约12％，并且用于颈缩的比能量密度接近于通过简单拉伸试验确定的比能量密度。 DENT与简单拉伸试验之间颈缩比能量密度的接近性为新方法表征聚乙烯大塑性变形和颈缩时的断裂行为提供了一定的支持。超高分子量聚乙烯（UHMWPE）也使用DENT测试进行了表征。但是，发现其断裂行为无法使用原始的EWF方法进行描述，并且由于不会发生颈缩，也无法通过新的机械方法进行描述。结果，开发了改进的EWF方法。为了证明改进的EWF方法的有效性，建立了能量平衡方程的公式，从中可以使用非线性趋势线确定断裂韧性。这项研究表明，原始的EWF方法不能用于处理断裂过程中涉及的大量塑性变形，以表征UHMWPE的断裂行为。

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  • 作者

    Cao, Wenrui.;

  • 作者单位

    University of Alberta (Canada).;

  • 授予单位 University of Alberta (Canada).;
  • 学科 Engineering Mechanical.
  • 学位 M.S.
  • 年度 2011
  • 页码 108 p.
  • 总页数 108
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 老年病学;
  • 关键词

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