Predicting variability in transverse effective elastic moduli and failure initiation strengths in UD composite microstructures due to randomness in fiber location and morphology
Predicting variability in transverse effective elastic moduli and failure initiation strengths in UD composite microstructures due to randomness in fiber location and morphology
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DOI：
10.1016/j.compstruct.2020.111887
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发表时间：
2020-04-01
影响因子：
6.3
通讯作者：
Fertig, Ray S., III
中科院分区：
文献类型：
--
作者：
Bhuiyan, Faisal H.;Sanei, Seyed Hamid R.;Fertig, Ray S., III
在这项研究中，通过对计算机生成的微观结构整体进行有限元分析，对由纤维几何描述符中存在的随机性（特别是纤维位置和形态）引起的单向（UD）复合材料横向力学性能的变化进行了量化。这些微观结构是根据实际微观结构的图像分析评估的几何描述符生成的。为了确保一致性，所有合成微观结构都经过修改，以匹配实际微观结构的短程和长程统计数据。该技术能够生成统计上相似但形态上不同的微观结构，即它们具有相同的统计数据但不同的配置。基于像素和基于形态的网格划分策略，为微观结构开发了基于图像的三维有限元模型，随后分别分析了弹性和强度特性。采用内聚区建模和扩展有限元方法来预测随机微结构在两种横向双轴载荷情况下的失效起始强度：（i）横向拉伸-横向拉伸和（ii）横向拉伸-横向剪切载荷。每个场景研究了七个负载比情况，即 0/1、0.2679/1,1/root 3、1/1、root 3/1、3.7321/1 和 1/0。为了证明所研究的 UD 复合材料微观结构双轴强度中存在的可变性，开发了显示三种不同可靠性水平轮廓的随机失效包络线。结果表明，微观结构变异对横向弹性模量几乎没有影响；然而，它显着影响横向强度。研究还发现，六边形堆积微观结构可以很好地估计平均有效弹性模量，但它大大高估了强度。
In this study, variability in transverse mechanical properties of unidirectional (UD) composites arising from the randomness present in the geometrical descriptors of the fibers, specifically fiber location and morphology was quantified via finite element analysis of an ensemble of computer-generated microstructures. These microstructures were produced based on geometrical descriptors evaluated from the image analysis of an actual microstructure. To ensure consistency, all synthetic microstructures were modified to match both the short-range and long-range statistics of the actual microstructure. This technique enabled generation of microstructures that are statistically similar but morphologically different, i.e. they have the same statistics but different configurations. Image-based three-dimensional finite element models were developed for the microstructures based on pixel and morphology-based meshing strategies and subsequently analyzed for elastic and strength properties, respectively. Cohesive zone modeling and extended finite element method were employed to predict failure initiation strengths of the stochastic microstructures under two transverse biaxial loading scenarios: (i) transverse tension - transverse tension and (ii) transverse tension - transverse shear loading. Seven load ratio cases were investigated for each scenario, namely 0/1, 0.2679/1,1/root 3, 1/1, root 3/1, 3.7321/1, and 1/0. To demonstrate the variability existing in the investigated biaxial strengths of the UD composite microstructures, stochastic failure envelopes showing contours of three different reliability levels were developed. The results indicated that microstructural variability has little to no influence on transverse elastic moduli; however, it significantly influences transverse strengths. It was also found that the hexagonal packing microstructure provides a good estimation for the average effective elastic moduli, however, it overpredicts the strengths by a large margin.