Abstract The production of continuous carbon fibre composites using a fused deposition modelling (FDM) method has addressed the problem of low mechanical performance of raw- or short-fibre reinforced polymer parts fabricated by the same process, due to the excellent specific strength and stiffness of continuous fibres. However, one key issue of 3D printed polymers or fibre-reinforced polymers is the formation of microscopic voids between individual filaments and within the filaments during the FDM process. This study aims to quantify the adverse effects of voids on 3D printed continuous fibre-reinforced polymer composites. Optical microscopy and micro-CT are used to quantify the void content in continuous CF/PA6 composites fabricated on a 3D printing platform. As a benchmark, 3D printed CF/PA6 composites with the same printing configurations were further processed by compression moulding (CM) with thickness controlled to achieve the minimum void content. Apart from tensile and three-point bending tests in the longitudinal and transverse directions, the study also evaluated the Mode I interlaminar fracture toughness of CF/PA6 composites. By revealing the substantial adverse effects of the microscopic voids in 3D printed composites, this study articulates the critical importance of developing in-process techniques during 3D printing to decrease the void content within the continuous fibre reinforced composites, for the sake of expanding practical applications of 3D printed continuous fibre composites.

中文翻译：

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3D 打印连续 CF/PA6 复合材料：微观空隙对机械性能的影响

摘要 使用熔融沉积模型 (FDM) 方法生产连续碳纤维复合材料解决了由相同工艺制造的原始或短纤维增强聚合物部件机械性能低的问题，这是由于其优异的比强度和刚度。连续纤维。然而，3D 打印聚合物或纤维增强聚合物的一个关键问题是在 FDM 过程中在单根长丝之间和长丝内形成微观空隙。本研究旨在量化空隙对 3D 打印连续纤维增强聚合物复合材料的不利影响。光学显微镜和显微 CT 用于量化在 3D 打印平台上制造的连续 CF/PA6 复合材料中的空隙含量。作为基准，具有相同打印配置的 3D 打印 CF/PA6 复合材料通过压缩成型 (CM) 进一步加工，厚度控制以实现最小空隙含量。除了纵向和横向的拉伸和三点弯曲试验外，该研究还评估了 CF/PA6 复合材料的 I 型层间断裂韧性。通过揭示 3D 打印复合材料中微观空隙的实质性不利影响，本研究阐明了在 3D 打印过程中开发过程技术以减少连续纤维增强复合材料中的空隙含量的关键重要性，以扩大 3D 打印复合材料的实际应用。 3D 打印连续纤维复合材料。除了纵向和横向的拉伸和三点弯曲试验外，该研究还评估了 CF/PA6 复合材料的 I 型层间断裂韧性。通过揭示 3D 打印复合材料中微观空隙的实质性不利影响，本研究阐明了在 3D 打印过程中开发过程技术以减少连续纤维增强复合材料中的空隙含量的关键重要性，以扩大其实际应用3D 打印连续纤维复合材料。除了纵向和横向的拉伸和三点弯曲试验外，该研究还评估了 CF/PA6 复合材料的 I 型层间断裂韧性。通过揭示 3D 打印复合材料中微观空隙的实质性不利影响，本研究阐明了在 3D 打印过程中开发过程技术以减少连续纤维增强复合材料中的空隙含量的关键重要性，以扩大其实际应用3D 打印连续纤维复合材料。