Towards optimization of a polymer filament tensile test for the material extrusion additive manufacturing process

The Material extrusion (MEX) is a popular additive manufacturing (AM) method that can process a wide range of feedstock materials the most common of which are in filament form. Currently, there is no standardized testing method for filament tensile properties, and researchers resort to 3D-printed dog-bone specimens. In this paper, the impact of the strain measurement device, knife edge type, gage length, testing speed, and oven-treatment on filament tensile properties is explored using an off-the-shelf fixture. It was found that an extensometer with blunt knife edges, a filament gage length of 165 mm, and 6.35 mm/min (0.25 in./min) testing speed can accurately evaluate tensile properties of Acrylonitrile Butadiene Styrene (ABS) filaments. This was supported by repeatably good failure modes and average failure locations close to the mid-point of the filament final gage length. In addition, an optimized raster path, and optimal 3D printing design and process parameters were used to manufacture dog-bone tensile specimens per ASTM D638-22 from the same ABS spool. Filament tensile properties were validated using material properties from the 3D-printed dog-bone specimens. Optimum filament testing parameters found in this study for ABS can be used for the initial test set-up for other filament materials.

材料挤出（Material Extrusion，MEX）是一种应用广泛的增材制造（Additive Manufacturing，AM）方法，可适配多种原料材料，其中最常见的加工原料为丝材形式。当前，针对丝材拉伸性能尚未形成标准化测试方法，研究人员通常采用3D打印哑铃状试样开展相关测试。本文借助一款现成商用夹具，探究了应变测量装置、刀口类型、标距、测试速度以及烘箱处理对丝材拉伸性能的影响。研究结果表明，采用钝刀口引伸计、165 mm的丝材标距以及6.35 mm/min（0.25 in./min）的测试速度，可精准测定丙烯腈-丁二烯-苯乙烯共聚物（Acrylonitrile Butadiene Styrene，ABS）丝材的拉伸性能。该结论得到了重复稳定的失效模式以及平均失效位置接近丝材最终标距中点的实验结果支撑。此外，本文采用优化后的扫描路径、最优3D打印设计与工艺参数，依据ASTM D638-22标准，使用同一卷ABS丝材打印了符合标准的哑铃状拉伸试样。通过3D打印哑铃状试样的材料性能，验证了丝材拉伸测试结果的可靠性。本研究针对ABS丝材得出的最优测试参数，可作为其他丝材材料初始测试搭建的参考依据。