Abstract Aging of composites is of great concern as it reduces durability. Diffusion plays an important role in aging, as it is responsible for transporting substance from the surface into the bulk. The microstructure of woven composites, which is complex and highly heterogeneous, makes diffusion analysis challenging. One way of simplifying the problem is by obtaining an effective diffusivity through homogenization and rules-of-mixtures. In this paper a homogenized through-the-thickness diffusivity of plain-woven composites is derived analytically with offset in the microstructure of the tows. A rule-of-mixtures based on Fickian diffusion and the volume fractions of constituents is proposed as an efficient way of obtaining the effective diffusion coefficient. The analytical expression is benchmarked against a three-dimensional orthotropic finite element analysis using material and geometrical parameters from the literature. Very good agreement between the two approaches is observed, which supports use of the homogenization. Notes on how this work could aid in understanding aging are included.

中文翻译：

---

来自分析均质化的平织复合材料的有效全厚度扩散率

摘要 复合材料的老化会降低耐久性，因此备受关注。扩散在老化中起着重要作用，因为它负责将物质从表面传输到本体中。编织复合材料的微观结构复杂且高度异质，这使得扩散分析具有挑战性。简化问题的一种方法是通过均质化和混合规则获得有效的扩散率。在本文中，通过丝束微观结构的偏移，分析得出了平纹编织复合材料的均匀全厚度扩散率。提出了一种基于 Fickian 扩散和成分体积分数的混合规则，作为获得有效扩散系数的有效方法。解析表达式以使用文献中的材料和几何参数的三维正交各向异性有限元分析为基准。观察到两种方法之间非常好的一致性，这支持使用均质化。包括关于这项工作如何有助于理解衰老的说明。