Development of Tensile Test Specimens for Fused Deposition Modeling

Abstract:

Standard test specimens are usually used to determine the tensile strengths of plastics. Their shape assumes that the material is homogeneous and only normal stress occur inside their nominal length. Unlike injection molding, which is a common technology to produce plastic parts, the structure of additively manufactured parts is not homogeneous. In areas with variable geometry, an additional internal stress concentration occurs, which often leads to failure of the test specimens outside their nominal length, which in turn compromises the tensile test. The stress concentration increases with the nozzle diameter used. This requires improvement of the test specimens shape. In the present work a new form of the test specimens is proposed, in accordance with the peculiarities of the Fused Deposition Modeling (FDM) process. A series of test specimens have been produced, using a 1mm and 2mm nozzle as well as one wall, no walls and milled specimens with newly developed geometry. All specimens were tensile tested and the results were shown and compared. It has been found that the proposed new shape ensures failure within the parallel length for successful testing, provided infill strands are correctly positioned.

• Periodical: Materials Science Forum (Volume 1058)
• Pages: 175-182
• DOI: https://doi.org/10.4028/p-24e2wo
• Online since: April 2022
• Authors: Maurice Schwicker*, Nikolay Nikolov
• Keywords: Finite Element Method, Fused Deposition Modeling, Fused Filament Fabrication, Infill Overlap, Tensile Test Specimen

References

[1] International Organization for Standardization 2019 ISO 527-1:2019 Plastics. Determination of tensile properties. General principles.

[2] International Association for Testing Materials 2014 ASTM D638-14 Standard Test Method for Tensile Properties of Plastics.

[3] International Organization for Standardization 2012 ISO 527-2:2012(E) Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and extrusion plastics vol Second edi.

DOI: 10.3403/30216860

[4] Wendt C, Batista M, Moreno E, Valerga A P, Fernández-Vidal S R, Droste O and Marcos M 2015 Preliminary Design and Analysis of Tensile Test Samples Developed by Additive Manufacturing Procedia Engineering vol 132.

DOI: 10.1016/j.proeng.2015.12.489

[5] García-Domínguez A, Claver J, Camacho A M and Sebastián M A 2020 Considerations on the applicability of test methods for mechanical characterization of materials manufactured by FDM Materials (Basel). 13.

DOI: 10.3390/ma13010028

[6] Croccolo D, De Agostinis M and Olmi G 2013 Experimental characterization and analytical modelling of the mechanical behaviour of fused deposition processed parts made of ABS-M30 Comput. Mater. Sci. 79.

DOI: 10.1016/j.commatsci.2013.06.041

[7] Ahn S, Montero M, Odell D, Roundy S and Wright P K 2002 Anisotropic material properties of fused deposition modeling ABS Rapid Prototyp. J. 8 248–57.

DOI: 10.1108/13552540210441166

[8] Schwicker M and Nikolov N 2021 Fused-Layer Modeling: from idea to physical part IOP Conf. Ser. Mater. Sci. Eng.

[9] Schwicker M and Nikolov N 2021 Development of a Fused-Layered Modelling system to build form-locked joints using an industrial robot IOP Conf. Ser. Mater. Sci. Eng.

[10] Kuznetsov V E, Solonin A N, Urzhumtsev O D, Schilling R and Tavitov A G 2018 Strength of PLA components fabricated with fused deposition technology using a desktop 3D printer as a function of geometrical parameters of the process Polymers (Basel). 10 313.

DOI: 10.3390/polym10030313

[11] Yadav P, Sahai A and Sharma R S 2021 Strength and Surface Characteristics of FDM-Based 3D Printed PLA Parts for Multiple Infill Design Patterns J. Inst. Eng. Ser. C 102.

DOI: 10.1007/s40032-020-00625-z

[12] Pandzic A, Hodzic D and Milovanovic A 2019 Effect of infill type and density on tensile properties of pla material for fdm process Annals of DAAAM and Proceedings of the International DAAAM Symposium vol 30.

DOI: 10.2507/30th.daaam.proceedings.074

[13] Dave H K, Patel B H, Rajpurohit S R, Prajapati A R and Nedelcu D 2021 Effect of multi-infill patterns on tensile behavior of FDM printed parts J. Brazilian Soc. Mech. Sci. Eng. 43.

DOI: 10.1007/s40430-020-02742-3