Fiber reinforced multiscale composites represent a cutting-edge class of advanced materials that have garnered significant attention in the realm of materials science and engineering. These advanced materials intertwine various fiber reinforcements, meticulously tailored at micro, to macro levels, imparting them with remarkable mechanical, thermal, and functional properties. In this research, an experimental investigation was performed to observe the tensile fatigue behavior of short and continuous carbon fiber reinforced additively manufactured multiscale thermoplastic composites. The multiscale composite was fabricated by combining layers of continuous woven carbon fiber (CCF) with short carbon fiber (SCF) reinforced acrylonitrile butadiene styrene (ABS) laminates which were additively manufactured using the fused filament fabrication technique. It was observed that the multiscale composite exhibits a maximum 127% higher strength and 154% higher Young’s modulus than neat ABS polymer. Based on non-normalized stress-life curves, multiscale composites with four layers of CCF have a higher fatigue strength than multiscale composites with one layer of CCF. However, when the applied stress is normalized by the quasi-static strength, the multiscale composite with one layer of CCF had a longer fatigue life than the four layers of CCF reinforced multiscale composites at high normalized cyclic stress, while the multiscale composite with four layers of CCF exhibited a longer fatigue life at low normalized cyclic stress. The four CCF layers reinforced multiscale composites experienced a different extent of fiber pull-out, matrix cracking, and delamination at different stress levels. Conversely, fatigue failure of the one layer of CCF reinforced multiscale composites primarily occurred due to localized fiber breakage with minimal matrix-related damage.

中文翻译：

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短连续碳纤维增强增材制造热塑性多尺度复合材料的拉伸疲劳行为

纤维增强多尺度复合材料代表了一类尖端的先进材料，在材料科学和工程领域引起了极大的关注。这些先进材料将各种纤维增强材料交织在一起，从微观到宏观层面精心定制，赋予它们卓越的机械、热和功能特性。在这项研究中，进行了实验研究，以观察短连续碳纤维增强增材制造的多尺度热塑性复合材料的拉伸疲劳行为。这种多尺度复合材料是通过将连续编织碳纤维（CCF）与短碳纤维（SCF）增强丙烯腈丁二烯苯乙烯（ABS）层压板相结合而制成的，这些层压板是使用熔丝制造技术增材制造的。据观察，多尺度复合材料的强度比纯 ABS 聚合物高出最多 127%，杨氏模量高出 154%。基于非归一化应力-寿命曲线，具有四层CCF的多尺度复合材料比具有一层CCF的多尺度复合材料具有更高的疲劳强度。然而，当施加的应力通过准静态强度归一化时，在高归一化循环应力下，具有一层CCF的多尺度复合材料比四层CCF增强的多尺度复合材料具有更长的疲劳寿命，而具有四层的多尺度复合材料具有更长的疲劳寿命。 CCF 在低标准化循环应力下表现出更长的疲劳寿命。四个 CCF 层增强的多尺度复合材料在不同的应力水平下经历了不同程度的纤维拔出、基体开裂和分层。相反，一层 CCF 增强多尺度复合材料的疲劳失效主要是由于局部纤维断裂而与基体相关的损伤最小。