Slager Jonathan J, Green Joshua T, Levine Samuel D, Gonzalez Roger V
Department of Mechanical and Nuclear Engineering, School of Engineering, Computing and Weapons, United States Naval Academy, Annapolis, MD 21402, USA.
Department of Engineering Education and Leadership, College of Engineering, The University of Texas at El Paso, El Paso, TX 79968, USA.
Polymers (Basel). 2025 Jul 25;17(15):2028. doi: 10.3390/polym17152028.
Discontinuous fibers are commonly added to matrix materials in additive manufacturing to enhance properties, but such benefits may be constrained by print and fiber orientation. The additive processes of forming rasters and layers in powder bed fusion inherently cause anisotropy in printed parts. Many print parameters, such as laser, temperature, and hatch pattern, influence the anisotropy of tensile properties. This study characterizes fiber orientation attributed to recoating non-encapsulated fibers and the resulting anisotropic tensile properties. Tensile and fracture properties of polyamide 12 reinforced with 0%, 2.5%, 5%, and 10% discontinuous carbon fibers by volume were characterized in two primary print/tensile loading orientations: tensile loading parallel to the recoater ("horizontal specimens") and tensile load along the build axis ("vertical specimens"). Density and fractographic analysis indicate a homogeneous mixture with low porosity and primary fiber orientation along the recoating direction for both print orientations. Neat specimens (zero fiber) loaded in either direction have similar tensile properties. However, fiber-reinforced vertical specimens have significantly reduced consistency and tensile strength as fiber content increased, while the opposite is true for horizontal specimens. These datasets and results provide a mechanism to tune material properties and improve the functionality of selectively laser-sintered fiber-reinforced parts through print orientation selection. These datasets could be used to customize functionally graded parts with multi-material selective laser-sintering manufacturing.
在增材制造中，通常会将不连续纤维添加到基体材料中以增强性能，但这些益处可能会受到打印和纤维取向的限制。粉末床熔融中形成光栅和层的增材工艺会在打印部件中固有地产生各向异性。许多打印参数，如激光、温度和扫描模式，都会影响拉伸性能的各向异性。本研究表征了由于重新涂覆未封装纤维而导致的纤维取向以及由此产生的各向异性拉伸性能。通过体积分数为0%、2.5%、5%和10%的不连续碳纤维增强的聚酰胺12的拉伸和断裂性能，在两个主要的打印/拉伸加载取向中进行了表征：平行于重新涂覆器的拉伸加载（“水平试样”）和沿构建轴的拉伸加载（“垂直试样”）。密度和断口分析表明，两种打印取向均为低孔隙率的均匀混合物，且初级纤维沿重新涂覆方向取向。在任一方向加载的纯试样（零纤维）具有相似的拉伸性能。然而，随着纤维含量的增加，纤维增强垂直试样的一致性和拉伸强度显著降低，而水平试样则相反。这些数据集和结果提供了一种机制，可通过打印取向选择来调整材料性能并改善选择性激光烧结纤维增强部件的功能。这些数据集可用于通过多材料选择性激光烧结制造来定制功能梯度部件。
