Consistency analysis of mechanical properties of elements produced by FDM additive manufacturing technology

Abstract

Additive manufacturing (AM) technology refers to the process of producing 3D objects by adding material in successive layers. Fused deposition modeling (FDM) is one of the AM technologies where objects are built by adding layers of melted thermoplastic filament onto the printing surface. Mechanical properties of FDM printed part depend on many influencing factors such as material composition, extruding temperature, printing parameters and environment temperature. The aim of this study was to investigate consistency of mechanical properties of elements produced by FDM additive manufacturing technology. To do so, mechanical tensile and compression tests were conducted on ten samples using polylactic acid (PLA) and ten samples using acrylonitrile butadiene styrene (ABS) thermoplastic material. Tensile tests were conducted using Shimadzu Compact Tabletop Testing Machine EZ-LX and the compression tests were done using VEB ZDM 5/91 testing machine. The ultimate tensile strength, strain, Young modulus and compression yield strength values were analyzed. The ABS thermoplastic material showed greater consistency in mechanical properties during tensile tests. Tensile strength values for PLA material varied between samples thus showing greater inconsistency in repeatability of mechanical properties. Compression tests, on the other hand, showed that PLA samples had greater consistency in mechanical properties compared to ABS samples.

Considerations on the Applicability of Test Methods for Mechanical Characterization of Materials Manufactured by FDM

“…The specimens after tensile testing are presented in Figure 8. Most of them break in close to the radius of fillet close to the grips, which is common for FDM specimens [27], and it is due to stress concentrations at fillet areas [10], being the kind of fracture brittle, with no plastic deformation observed. As Wu et al reported [28], craze is the main plastic deformation mechanism of ABS, and a great number of crazes are generated perpendicular to the load direction.…”

“…Comparison of mechanical properties in samples with solid (ASTM-O1, ASTM-O2) and non-solid (S1, S2, S3) infill. Tensile strengths of ABS parts obtained by FDM have been reported to be in the range of 11-40 MPa [10]; the explanation to this wide range is associated to their anisotropic behavior. Results are in good agreement with previous works such as the one by Tymrak et al [33], with tensile strengths around 30 MPa, or the work by Banjanin et al [10], with an average value of tensile stresses for ABS samples of 31 MPa, considering that they used non-solid specimens, so they are expected to have lower values than the ones obtained in our work with solid ones; in fact, these reference values are in very good agreement with the ones obtained in our previous work with non-solid samples [26], used for comparison in this section.…”

“…The experiences developed by researchers when applying these standards in additive contexts have a key role, since the obtained results help to clarify the applicability or not of these standards in different additive scenarios, as well as to provide action guidelines. A significant variety of approaches have been faced in order to determinate the influence of manufacturing parameters on the mechanical response of additive products; for example, ABS specimens for unmanned aerial systems produced by FDM were characterized under tension [8] and under compression [9]; Banjanin et al [10] evaluated the mechanical response of specimens of polylactide (PLA) and acrylonitrile styrene butadiene (ABS), concluding that the results in ABS showed a higher repeatability under tension than under compression, and vice versa. Chacón et al [11] assessed the effect of build orientation, layer thickness, and feed rate on the mechanical performance of PLA specimens, stating that, for optimal mechanical performance, low layer thickness and high feed rate values are recommended.…”

Mechanical characterization of polylactic acid, polycaprolactone and Lay-Fomm 40 parts manufactured by fused deposition modeling, as a function of the printing parameters

“…Una de las principales problemáticas que presenta esta tecnología es la elección de los parámetros de impresión correctos de acuerdo con el material [6], ya que estos afectan las propiedades mecánicas y la capacidad de uso final de la pieza [7]. Se han realizado diferentes estudios en los que se analiza la dependencia de las propiedades mecánicas con los parámetros de impresión para piezas fabricadas con filamentos de acrilonitrilo butadieno estireno (ABS) y ácido poliláctico (PLA) [8][9][10][11], materiales poliméricos que son usados frecuentemente con este tipo de tecnología por ser los más estables [5].…”

Strength Increasing Additive Manufacturing Fused Filament Fabrication Technology, Based on Spiral Toolpath Material Deposition

“…The transition from "cut" to "printed" products raises the question of comparing their strength, especially for products, printed using FFF technology. It is related to the fact that due to the physical properties of polymeric materials, which are often used by this technology, when melting their macromolecules are stretched in the direction of flow, resulting in objects printed by the FFF method being characterized by anisotropy [5][6][7][8]. Test data comparison of samples printed from the most common acrylonitrile butadiene styrene (ABS) and polylactide (PLA) plastics with the results of samples being made, for example, with a screw extruder [9], does not speak in favor of 3D printing, if the load is applied not along, but across, the layers.…”