PSI - Issue 56

Zorana Golubovic et al. / Procedia Structural Integrity 56 (2024) 153–159 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Tensile results from both standard ABS and ABS resin material, using these three mentioned AM technologies, vary significantly (see Fig. 4). In general, AM parts obtained from the extrusion process have overall better mechanical properties than parts created from the polymerization of resin material. But SLA specimens here have higher UTS than FDM ones. However, DLP tensile results show lower UTS than FDM’s (see Figs. 3 and 4). This advantage of SLA can be explained by finer materials’ structure due to higher UV laser energies during the AM process. On the other hand, the lower energy of LCD projected UV light and the existence of bubbles in the resin created highly anisotropic DLP specimens. Hence, the UTS values significantly depend upon the AM technology utilized, even though the material is the same. Here, the SLA proved to be better than the other two AM technologies (see Fig. 3). Regarding the elastic modulus, the SLA values are quite similar to the FDM ones. This statement may be visualized as the overlap of both average curves in their linear regions (see Fig. 3). However, the DLP’s elastic modulus is distinctly lower. Quantitative values of elastic modulus are shown in Fig. 4. DLP has proven that it is a better option regarding the maximum strain and elongation at break (see Fig. 4). Their overall elongation is more than double in value, compared to the other two observed AM technologies. Hence, the DLP is sufficiently tougher although the material used is the same photosensitive resin as in the SLA process. One may conclude that the utilized AM technology has an effect on overall strain values.

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Fig. 4. a) Elastic modulus and UTS chart, and b) maximum strain and elongation at break chart.

The absorbed energy during the tensile process was also monitored here. Worth pointing out is that this absorbed energy is interpreted as an area underneath the stress- strain diagrams from Fig. 3. Hence, DLP’s value is approx. 1.09 J while the value for SLA and FDM are 0.43 J and 0.73 J, respectively. Therefore, this information goes along with the fact that DLP’s can strain more than the other two. This may also be influenced by the post-printing process that DLP specimens underwent. As additional info, the DLP specimens appeared more rubber-like when touched than the SLA ones. 4. Conclusions Both tensile properties and fracture surface morphology of standard ABS filament and novel resin material has been analyzed, leading to a more comprehensive understanding of the differences between the two. In tensile tests, all the tested materials experienced predominantly brittle behavior upon fracture. FDM and SLA have been shown to have similar elastic modulus, with quantitative values around 2.2 GPa. The presence of bubbles in DLP specimens has shown its effect on the elastic modulus namely, these defects decrease the property value. Regarding UTS, the SLA has proven to be the best AM technology of the monitored three. One should not forget that the SLA device used here is an industry-grade machine, in contrast to desktop FDM and DLP devices. However, the DLP has higher overall elongation and higher total energy absorption.