Digital manufacturing was employed to 3D print continuous Carbon, Glass and Kevlar fibre reinforced composites in Unidirectional (UD) [0°], Off-axis ±45° and Cross-ply [0°/90°] layup sequence. These 3D printed composites were subjected to quasi-static, in-plane tension and out-of-plane (compression and shear) loading. The tensile strength of 3D printed Carbon, Glass and Kevlar UD laminates was significantly lower than that of 3D printing filaments used to manufacture them. The type of fibre (brittle/ductile) reinforcement was found to be governing the shear yield strength of 3D printed composites despite having the same Nylon matrix in all the composites. Out-of-plane compressive strength of the 3D printed Carbon and Glass fibre reinforced composites was independent of specimen size. Contrary to that, Kevlar fibre composites showed a pronounced size effect upon their out-of-plane compressive strength. A combination of X-ray tomography and pressure film measurements revealed that the fibres in 3D printed composites failed by ‘indirect tension’ mechanism which governed their out-of-plane compressive strength. To gain further insights on the experimental observations, Finite Element (FE) simulations were carried out using a pressure-dependent crystal plasticity framework, in conjunction with an analytical model based on shear-lag approach. Both FE and analytical model accurately predicted the out-of-plane compressive strength of all (Carbon, Glass and Kevlar fibre reinforced) 3D printed composites.

中文翻译：

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增材制造的交叉层复合材料的面外压缩响应

采用数字制造技术以单向 (UD) [0°]、离轴 ±45° 和交叉层 [0°/90°] 叠层顺序 3D 打印连续的碳纤维、玻璃和凯夫拉纤维增强复合材料。这些 3D 打印复合材料承受准静态、面内张力和面外（压缩和剪切）载荷。3D 打印碳、玻璃和 Kevlar UD 层压板的拉伸强度明显低于用于制造它们的 3D 打印长丝。尽管所有复合材料都具有相同的尼龙基体，但发现纤维（脆性/韧性）增强材料的类型决定了 3D 打印复合材料的剪切屈服强度。3D 打印碳纤维和玻璃纤维增​​强复合材料的面外压缩强度与试样尺寸无关。与此相反，Kevlar 纤维复合材料对它们的面外压缩强度显示出明显的尺寸效应。X 射线断层扫描和压力膜测量的组合表明，3D 打印复合材料中的纤维因“间接张力”机制而失效，该机制控制了它们的面外压缩强度。为了进一步了解实验观察，有限元 (FE) 模拟是使用依赖于压力的晶体塑性框架结合基于剪切滞后方法的分析模型进行的。FE 和分析模型都准确预测了所有（碳纤维、玻璃纤维和凯夫拉纤维增强）3D 打印复合材料的面外压缩强度。X 射线断层扫描和压力膜测量的组合表明，3D 打印复合材料中的纤维因“间接张力”机制而失效，该机制控制了它们的面外压缩强度。为了进一步了解实验观察，有限元 (FE) 模拟是使用依赖于压力的晶体塑性框架结合基于剪切滞后方法的分析模型进行的。FE 和分析模型都准确预测了所有（碳纤维、玻璃纤维和凯夫拉纤维增强）3D 打印复合材料的面外压缩强度。X 射线断层扫描和压力膜测量的组合表明，3D 打印复合材料中的纤维因“间接张力”机制而失效，该机制控制了它们的面外压缩强度。为了进一步了解实验观察，有限元 (FE) 模拟是使用依赖于压力的晶体塑性框架结合基于剪切滞后方法的分析模型进行的。FE 和分析模型都准确预测了所有（碳纤维、玻璃纤维和凯夫拉纤维增强）3D 打印复合材料的面外压缩强度。有限元 (FE) 模拟是使用与压力相关的晶体塑性框架结合基于剪切滞后方法的分析模型进行的。FE 和分析模型都准确预测了所有（碳纤维、玻璃纤维和凯夫拉纤维增强）3D 打印复合材料的面外压缩强度。有限元 (FE) 模拟是使用与压力相关的晶体塑性框架结合基于剪切滞后方法的分析模型进行的。FE 和分析模型都准确预测了所有（碳、玻璃和凯夫拉纤维增强）3D 打印复合材料的面外压缩强度。