Anisotropic mechanical property variance between ASTM D638-14 type i and type iv fused filament fabricated specimens
Résumé
The open source introduction of fused filament fabrication (FFF) enables distributed manufacturing of consumer products. However, with a wide range of low-cost FFF 3-D printers and settings possible, there is a lack of information on the variability in printed mechanical properties. This paper utilizes a large pool of 47 user-assembled 3-D printers to quantify the mechanical property variations of ultimate tensile strength (UTS) and yield strength of FFF printed components using ASTM D638-14 horizontally-oriented Type I and IV geometries for poly lactic acid (PLA). The results indicate that utilizing Type IV tensile test piece geometry may overestimate the UTS relative to the Type I. Furthermore, anisotropic mechanical property variances were quantified for Type IV specimens (vertical and horizontal orientations). Vertical tensile specimens had an ultimate tensile strength 47.9% less than horizontal. Finally, the abundant supply of PLA 3-D prints suggest open-source printers assembled by individual operators can produce quality plastic components although the mechanical performance of the given part can vary dramatically based on the operator selection of printing parameters that provide a visually acceptable part. Highlights > Wide range of FFF 3-D printers and settings create variability in printed mechanical properties > Here a large pool of user-assembled 3-D printers to quantify ultimate tensile strength (UTS) > and yield strength using ASTM D638-14 horizontally-oriented Type I and IV geometries > Tensile strengths of 61.6 and 60.9 MPa were observed for Type IV and Type I, respectively > Check: Tensile component geometry is equivalent to the desired printed component geometry 1. Introduction With the open source introduction of fused filament fabrication (FFF) with the self REPlicating RAPid Prototyper (RepRap) [1-3] technology, the low-cost 3-D printing market has expanded [4]. The advancement of FFF requires quantitative mechanical property characterization [5] based on process parameters [6]. Significant efforts have been made on this front including investigating impact absorption [7], frictional performance [8], strain rate sensitivity [9], fatigue [10] and tensile strength [11, 12]. In addition, past work has evaluated the effects of colorants [13], raster [14], raster and thickness [15-17], layer orientation [18], infill patterns [19], ambient gas [20], vibration of printer [21], porosity [22] and the number of cycles through the system for recycled polymers [23]. Furthermore, composites have been evaluated for the inclusion of waste bio materials [24], nanoparticles [25], wood fibre [26], waste wood [27], fibre reinformcent [28] and carbon nanotubes [29] on mechanical properties. Layer-wise manufacturing methods induce directionally dependent mechanical properties [12, 30-33]. Anisotropy is most significant in a comparison between vertically and horizontally orientated, relative to the building platform, printed components. Optimized
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