Fiber reinforced thermoplastic composites are limited due to poor interfacial bonding between the nonpolar/nonreactive polymer matrix and fiber surface. Recently, a concept of controlled mechanical interlocking between fiber and matrix surface was proposed to improve the interfacial bonding in fiber reinforced thermoplastic composites. Study results show promising performance of the approach under static loading conditions. In this work, we study the effect of strain rate on the interfacial bonding behavior under dynamic loading conditions. A parametric study of the strain rate effect is performed for which different surface microarchitectures of a glass/polypropylene composite system are considered. A three network model is implemented for modeling mechanical behavior of polymer, which is calibrated using a set of stress–strain curves experimentally obtained at various strain rates. The strength calculations address both polymer fracture and detachment of the polymer matrix from the anchoring sites. The results show that under the strain rates ranging from 2 × 10⁻⁴/s to 2 × 10⁻¹/s, even without any interfacial friction or adhesion, the interfacial shear strength could achieve close to 70% of the theoretical strength of perfect matrix-fiber bonding. It is observed that, while strain rate has appreciable effects on the fiber/matrix interfacial strength and can cause change of failure mode in some cases; its influence also depends on the geometry of the anchoring sites. Moreover, there is an optimal geometric configuration at which maximum failure strength is achieved. Graphic charts showing the dependency of interfacial strength on the strain rate and geometric configuration parameters are obtained.

中文翻译：

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具有机械互锁的热塑性复合材料的应变率效应

由于非极性/非反应性聚合物基体和纤维表面之间的界面结合不良，纤维增强热塑性复合材料受到限制。最近，提出了纤维和基体表面之间受控机械互锁的概念，以改善纤维增强热塑性复合材料的界面结合。研究结果表明该方法在静态载荷条件下具有良好的性能。在这项工作中，我们研究了动态加载条件下应变率对界面结合行为的影响。进行了应变率效应的参数研究，其中考虑了玻璃/聚丙烯复合材料系统的不同表面微结构。实现了一个三网络模型来模拟聚合物的机械行为，它使用一组在不同应变率下通过实验获得的应力-应变曲线进行校准。强度计算解决了聚合物断裂和聚合物基体与锚固位点的分离。结果表明，在 2 × 10^-4 /s 到 2 × 10 ^-1 /s，即使没有任何界面摩擦或粘附，界面剪切强度也可以达到接近完美基体-纤维粘合理论强度的 70%。据观察，虽然应变速率对纤维/基体界面强度有明显影响，但在某些情况下会导致失效模式的变化；它的影响还取决于锚定点的几何形状。此外，还有一个最佳的几何配置，在该配置下可以达到最大的失效强度。获得显示界面强度对应变率和几何配置参数的依赖性的图表。