权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Homogenization Analysis and Experimental Verification for Creep of Unidirectional Fiber Reinforced Composites

单向纤维增强复合材料蠕变均匀化分析及实验验证

基本信息

批准号：
09450046
负责人：
OHNO Nobutada
金额：
$ 1.34万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450046/
关键词：
Composite Material Creep Homogenization Theory Periodic Structure

项目摘要

1. A homogenization theory was formulated for time-dependent nonlinear composites with periodic internal structures, so that perturbed displacement rate is decomposed into time-independent elastic and time-dependent viscoplastic parts. Then a macroscopic constitutive relation and a microscopic evolution equation of stress were derived.2. The theory mentioned above was applied to analyzing transverse creep and elastic-viscoplastic deformation of unidirectional composites reinforced with continuous fibers. Assuming the plane strain condition in the fiber orientation, and employing the square and hexagonal arrays of fibers, it was shown that the square and hexagonal arrays exhibit significant and negligible anisotropy in macroscopic behavior, respectively.3. The field of perturbed displacement rate was discussed by assuming the point symmetry of internal distributions with respect to a cell center. It was thus shown that the field of perturbed displacement rate is point-symmetric with respect to cell facet centers as well as the cell center, and that perturbed displacement rate vanishes at these centers. This finding led to introducing a semiunit cell, on the boundary of which the point symmetry is imposed on perturbed displacement rate as its boundary condition.4. The present theory was employed to analyze off-axial elastic-viscoplastic deformation of a hexagonally fiber-arrayed composite. It was then found that a small off-axis angle gives rise to significant decrease of viscoplastic flow stress, but that viscoplastic flow stress changes little for off-axis angles larger than 45 degree.5. Comparison of the analytical result mentioned above with experimental results on a hybrid composite GLARE 2 showed that the dependence of elastic-viscoplastic behavior on off-axis angle revealed in the present analysis is observed experimentally.

1. 建立了具有周期性内部结构的时变非线性复合材料的均匀化理论，将扰动位移率分解为时变弹性和时变粘塑性两部分。然后推导了宏观本构关系和微观应力演化方程。将上述理论应用于连续纤维增强单向复合材料的横向蠕变和弹粘塑性变形分析。假设纤维取向的平面应变条件下，采用正方形和六角形纤维阵列，结果表明正方形和六角形纤维阵列在宏观行为上分别表现出显著和可忽略的各向异性。通过假设胞内分布相对于胞中心的点对称，讨论了微扰位移率场。结果表明，微扰位移率场相对于细胞面中心和细胞中心是点对称的，微扰位移率在这些中心处消失。这一发现导致引入了一个半单元格，在其边界上，点对称性施加于扰动位移率作为其边界条件。利用该理论分析了六边形纤维排列复合材料的离轴弹粘塑性变形。结果表明，当离轴角较小时，粘塑性流动应力显著降低，而当离轴角大于45°时，粘塑性流动应力变化不大。将上述分析结果与杂化复合材料GLARE 2的实验结果进行了比较，结果表明，本分析所揭示的弹粘塑性特性与离轴角的关系是实验观察到的。