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.