Abstract
The Averaged Strain Energy Density (ASED) criterion is validated for the failure prediction of notched Polylactide Acid specimens fabricated by Fused Deposition Modeling by means of experimental data and the results are compared to the Theory of Critical Distances. The common approach of estimating the ASED control volume radius based on the measured fracture toughness was shown to be suboptimal, arguably because of the difficulties of obtaining the fracture toughness with such complex materials. Therefore, a more robust approach is evaluated in analogy of the TCD and it is shown to successfully extend the range of applicability of the ASED criterion.
Highlights
Fused Deposition Modeling (FDM), referred to as Fused Filament Fabrication (FFF), is one of the most mature technologies in additive manufacturing and has gained much popularity for low melting point polymers due to its low cost in use and maintenance [1]
The Averaged Strain Energy Density (ASED) criterion was validated for notched FDM-produced Polylactic Acid (PLA) specimens and a robust length scale calibration procedure was presented
This deficiency can be attributed to the difficulties in measuring the fracture toughness of locally heterogeneous media and the limits of linear elastic fracture mechanics on the homogenized material, both reflecting the inherent multi-scale nature of additive manufacturing
Summary
Fused Deposition Modeling (FDM), referred to as Fused Filament Fabrication (FFF), is one of the most mature technologies in additive manufacturing and has gained much popularity for low melting point polymers due to its low cost in use and maintenance [1]. As a consequence of all three strength reduction mechanisms mentioned above, inter-fiber failure occurs at much lower stress levels than intra-fiber failure, making θ = 0◦ the best choice for a high tensile strength [12,13], whereas θ = 45◦ was shown to maximize the fatigue life [12] The intensity of this effect depends on the inter-filament fusion quality and on other process parameters [17]. Two well-known methods for achieving this are the Theory of Critical Distances (TCD) [30] and the Averaged Strain Energy Density (ASED) criterion [31] In this context, Ahmed and Susmel [32,33,34] studied the quasi-static failure of FDM-printed notched PLA components, with a focus on validating the applicability of the Theory of Critical Distances (TCD). Based on the preliminary results for V-notched specimens under bending in [36], this work constitutes an in-depth analysis of the entire data set, the corresponding predictions, and the calibration procedure
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