Modeling unidirectional composites by bundling fibers into strips with experimental determination of shear and compression properties at high pressures
Modeling unidirectional composites by bundling fibers into strips with experimental determination of shear and compression properties at high pressures
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DOI：
10.1016/j.compscitech.2014.06.016
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发表时间：
2014-09-12
影响因子：
9.1
通讯作者：
Walker, James D.
中科院分区：
文献类型：
--
作者：
Chocron, Sidney;Nicholls, Arthur E.;Walker, James D.
超高分子量聚乙烯（UHMWPE）单向板（如Dyneema（R）HB 80或Spectra（R））的数值模型一直是一项艰巨的挑战。这个问题是由材料的紧密结构引起的。它是一个巨大的纤维集合体，由基质松散地结合在一起。例如，对于HB 80，纤维的直径非常小（类似于17 μ m），但非常强（类似于3.5GPa）。基质的量很小（体积约为20%），并且非常弱。用于这种材料的数值模型的“自然”尺度是纤维尺度（约为17 μ m）。该标度将提供正确的声速、横波速度、失效应变、层压板的强度、挠曲、纤维/层之间的滑移等，如果我们想要具有预测能力，这些都是必要的细节。但即使有非常强大的计算机，我们仍然远远不能模拟一个真正大小的层压目标本文提出了一种“中间”尺度，将许多纤维捆绑或合并在一起，以便在几个小时内解决数值问题（或对于厚目标最多一天或两天）的计算。精确地选择尺度，以便保持弹道学问题的基本物理特性，并且所使用的材料特性是在实验室中测量的纤维和基质的特性。类似的方法在以前的文件中提出的织物（凯夫拉，Dyneema，PBO），纱线级模型能够再现波的传播模式和弹道limits.This本文首先介绍了新材料的测试结果（剪切和压缩在低和高的约束压力）。这些对于正确捕获材料分层至关重要。然后，为了完整性，横向波传播和弹道结果Dyneema发表在其他地方简要介绍。最后，在LS-DYNA中建立了数值模型，并与挠度历史和弹道极限进行了比较。(C)2014爱思唯尔有限公司版权所有。
Numerical models of unidirectional panels of ultra-high-molecular weight polyethylene (UHMWPE), like Dyneema (R) HB80 or Spectra (R), have been a difficult challenge. The problem arises from the intimate structure of the material. It is a huge collection of fibers loosely held together by a matrix. For example, for HB80 the fibers are very small in diameter (similar to 17 mu m) but extremely strong (similar to 3.5 GPa). The amount of matrix is small (similar to 20% in volume) and very weak.The "natural" scale to use in the numerical model for this material is the fiber scale (similar to 17 mu m). This scale would provide the right sound speed, transverse wave speed, failure strain, strength of the laminate, deflection, slippage between the fibers/layers, etc. which are all essential details if we want to have predictive capability. But even with the very powerful computers available nowadays we are still very far from being able to simulate a real-size laminated target (for example 30 cm wide and 1 or 2 cm thick) at the fiber scale.This paper proposes an "intermediate" scale that bundles or consolidates many fibers together so that the numerical problem is solvable in a few hours (or maximum one or two days for thick targets) of computation in a single board (24 processors). The scale is chosen precisely so that the essential physics of the ballistics problem is kept and the material properties used are the ones measured in the lab for the fiber and matrix. A similar approach was presented in a previous paper for fabrics (Kevlar, Dyneema, and PBO) where a yarn-level model was able to reproduce both the wave propagation patterns and the ballistic limits.This paper first describes new material test results (shear and compression at low and high confinement pressures). These were essential in properly capturing the delamination of the material. Then, for completeness, transverse wave propagation and ballistics results in Dyneema published elsewhere are briefly presented. Finally the numerical model in LS-DYNA is developed and comparison with deflection history and ballistic limits is conferred. (C) 2014 Elsevier Ltd. All rights reserved.