The optimal performance of composites enriched with hollow spheres has been reported in contemporary literature, whereas their thermal properties have received less attention. In this regard, a finite element method (FEM)-based micromechanical model has been developed systematically to investigate the role of intra-matrix embedding of hollow spheres on the thermal conductivity and coefficient of thermal expansion (CTE) of unidirectional fiber-reinforced hybrid composites. In so doing, the concept of representative volume element (RVE) considers microstructures comprising an epoxy matrix, E-glass fiber, and E-glass hollow spheres, assuming perfect bonding (ideal interface) between the components and modified approximate periodic boundary conditions. By computing the longitudinal and transverse temperature gradients generated due to the application of uniform heat flux as well as the geometrical variation in RVE owing to temperature enhancement, thermal conductivity and CTE have been respectively determined. Comprehensive evaluations have been conducted to examine the effects of microstructural-level features, including fiber volume content and orientation, plus volume content and thickness of hollow spheres, on the effective thermal conductivity and CTE of pseudo-porous ternary E-glass/epoxy composites.

中文翻译：

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空心球填充玻璃纤维增​​强聚合物杂化复合材料导热系数和热膨胀系数的数值预测

当代文献中已经报道了富含空心球的复合材料的最佳性能，但其热性能却很少受到关注。在这方面，系统地开发了基于有限元法（FEM）的微机械模型，以研究基体内嵌入空心球对单向纤维增强混合复合材料的导热率和热膨胀系数（CTE）的作用。在此过程中，代表性体积单元 (RVE) 的概念考虑了包含环氧树脂基体、无碱玻璃纤维和无碱玻璃空心球的微结构，假设组件之间存在完美结合（理想界面）并修改了近似周期性边界条件。通过计算由于施加均匀热通量而产生的纵向和横向温度梯度以及由于温度升高而引起的RVE几何变化，分别确定了热导率和CTE。我们进行了综合评估，以检验微结构水平特征（包括纤维体积含量和取向，以及空心球的体积含量和厚度）对伪多孔三元E-玻璃/环氧树脂复合材料的有效导热率和CTE的影响。