Optimization of Fiber Coatings to Minimize Stress Concentrations in Composite Materials
Optimization of Fiber Coatings to Minimize Stress Concentrations in Composite Materials
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DOI：
10.1177/002199839302700603
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发表时间：
1993-06
影响因子：
2.9
通讯作者：
G. Carman;R. Averill;K. Reifsnider;J. Reddy
中科院分区：
文献类型：
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作者：
G. Carman;R. Averill;K. Reifsnider;J. Reddy
本文利用同心圆柱模型分析了连续增强涂层纤维复合材料在横向载荷作用下的应力状态。我们将这种分析纳入一个有条不紊的方法，以确定最佳的纤维相间涂层，以最大限度地提高复合材料的横向应变失效。本研究的重点是界面杨氏模量对应力状态的复合材料的基体材料进行恒应变（位移）边界条件的影响。我们证明，通过分析不同的涂层模量，存在一个最佳的三相属性，最大限度地减少最大主应力和应变能密度的复合材料。这些量的最小化清楚地表明，在具有最佳纤维涂层的复合材料中，失效起始将在显著更大的应变水平下发生。因此，我们假设（根据目前的分析），复合材料系统的横向应变失效可以增加适当的纤维涂层。给出了AS-4/Epon 828复合材料系统的结果和设计曲线，这表明对于大纤维体积分数（即，60%）最佳涂层是弹性体材料。该复合材料的数据表明，通过用最佳涂层涂覆结构纤维，失效应变可以增加多达6倍。恒定应力边界条件（即，优化强度）和恒定应变边界条件（即，优化失效应变）。
In this article we utilize a concentric cylinder model to analyze the stress state in a continuously reinforced coated fiber composite subjected to transverse loading. We incorporate this analysis into a methodical approach to determine an optimal inter phase coating for the fibers to maximize the composite's transverse strain to failure. The present study focuses on the effect of interphase Young's modulus on the stress state in the matrix material of a composite subjected to constant strain (displacement) boundary con ditions. We demonstrate, by analytically varying the coating modulus, that an optimum in terphase property exists which minimizes the maximum principal stress and the strain en ergy density in the composite material. The minimization of these quantities clearly indicates that failure initiation in a composite with an optimal fiber coating will occur at a significantly larger strain level. Therefore, we postulate (based on the current analysis) that the transverse strain to failure of a composite system can be increased with appropriate fiber coatings. Results and design curves are presented for an AS-4/Epon 828 composite system which suggest that for large fiber volume fractions (i.e., 60%) the optimum coating is an elastomeric material. The data presented on this composite suggest that the strain to failure can be increased as much as 6 times by coating the structural fibers with an optimal coating. A comparison between constant stress boundary conditions (i.e., optimizing strength) and constant strain boundary conditions (i.e., optimizing strain to failure) are also presented.