Е-Публикации
Технически университет - София

Abstract: Additive manufacturing technologies are increasingly used in engineering production, including in the field of transport. They allow the necessary parts to be obtained quickly and cost-effectively, sparing the prototyping phase and the machines and tooling investments. The mechanical properties of the obtained products are often comparable to those of the parts produced from the same materials but using classical technologies. The most common additive manufacturing technologies are Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS). In both technologies building is done in layers which orientation affects the final product structure, surfaces, and mechanical properties. The mechanical properties of the additively manufactured parts must be carefully studied - both to ensure their strength and to obtain the necessary data for CAE stress-strain analysis. In the present study, the tensile and torsional behavior of polyamide PA12 specimens produced by SLS technology were determined. Three different layers orientations were used - longitudinal, transverse and 45°. Five specimens of each type were produced and tested. The results are presented in graphical and tabular form, averaged and analyzed. It is stablished that with the SLS technology used, the orientation of the layers has little effect on the mechanical properties, and the theoretical dependence between the Young's modulus, Shear modulus and Poisson's ratio, valid for isotropic materials, is fulfilled.

References

1. ISO 17296-2:2017-Additive Manufacturing-General Principles-Part 2: Overview of Process Categories and Feedstock, (2017).
2. T. Wohlers, 3D Printing and Additive Manufacturing State of the Industry. Annual Worldwide Progress Report., Wohlers Report, Executive summary.
3. K. Nikolov, V. Tsonev, "Mechanical properties of polymer material test pieces, derived by additive manufacturing ", in Proceedings of Int. Sci. Conf. on Aeronautics, Automotive and Railway Engineering and Technologies BulTrans-2020, (Technical University of Sofia Publishing House, Sofia, 2020), pp. 35-45, (in Bulgarian).
4. T. Wohlers, I. Campbell, O. Diegel, R. Huff, and J. Kowen, Wohlers Report 2020: 3D Printing and Additive Manufacturing State of the Industry (Wohlers Associates, 2020).
5. T. Letcher, B. Rankouhi, and S. Javadpour, "Experimental study of mechanical properties of additively manufactured ABS plastic as a function of layer parameters," in Proceedings of the ASME 2015 International Mechanical Engineering Congress and Exposition. Volume 2A: Advanced Manufacturing, (13-19 November 2015, Houston, Texas, USA).
6. G. Goh, et al., "Process-structure-properties in polymer additive manufacturing via material extrusion: A review," Critical Reviews in Solid State and Materials Sciences 45, pp. 113-133 (2019).
7. R. Goodridge and S. Ziegelmeier, Powder Bed Fusion of Polymers, in Laser Additive Manufacturing, edited by M. Brandt (Woodhead Publishing, 2017), pp. 181-204.
8. A. Pilipović, T. Brajlih, and I. Drstvenšek, "Influence of processing parameters on tensile properties of SLS polymer product," Polymers 10, 1208 (2018).
9. A. Pilipović, et al., "Influence of laser sintering parameters on mechanical properties of polymer products," in 3rd International Conference on Additive Technologies ICAT2010, (DAAAM International, Vienna, 2010).
10. ISO 6892-2:2018 Metallic Materials-Tensile Testing-Part 2: Method of Test at Elevated Temperature, (2018).
11. ASTM 938-97 Standard Test Method for Torsion Testing of Wire, (1997).
12. V. Tsonev, B. Borisov, I. Muhtarov, and N. Kuzmanov, "Testing machine for experimental investigation in high temperature conditions," in Proceedings of Int. Sci. Conf. on Aeronautics, Automotive and Railway Engineering and Technologies BulTrans-2017 (Technical University of Sofia Publishing House, Sofia, 2017), pp. 64-68, (in Bulgarian).
13. N. Nikolov, V. Tsonev, and L. Lazov, "Controlling of stand for materials testing at high temperatures," in AMO '2010 (Sv. Konstantin i Elena, Bulgaria, 2010), pp. 315-319.
14. N. Nikolov, B. Borisov, and N. Kuzmanov, "Creation of pure torsion testing machine intended for laboratory works," in Proceedings of Int. Sci. Conf. on Aeronautics, Automotive and Railway Engineering and Technologies BulTrans-2015, (Technical University of Sofia Publishing House, Sofia, 2015), pp. 50-54, (in Bulgarian).
15. N. Nikolov and B. Borisov, "Working methodology for newly created pure torsion testing machine," in Proceedings of Int. Sci. Conf. on Aeronautics, Automotive and Railway Engineering and Technologies BulTrans-2015 (Technical University of Sofia Publishing House, Sofia, 2015), pp. 55-59, (in Bulgarian).
16. F. P. Beer, et al., Mechanics of Materials Seventh Edition (McGraw-Hill Education, 2015).
17. R. C. Hibbeler, Mechanics of Materials, Tenth Edition in SI Units (Pearson Education, Inc., Harlow, UK, 2018).
18. A. Nadai, Theory of Flow and Fracture of Solids, Second Ed., Vol. 1 (McGraw-Hill Book Co, New York, 1950).
19. BDS 1196-71 Metals. Methods for Torsion Test, (1971).
20. ISO 18338:2021 Metallic Materials-Torsion Test at Ambient Temperature (2021).

Issue