scholarly journals Experimental, Computational, and Dimensional Analysis of the Mechanical Performance of Fused Filament Fabrication Parts

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1766
Author(s):  
Iván Rivet ◽  
Narges Dialami ◽  
Miguel Cervera ◽  
Michele Chiumenti ◽  
Guillermo Reyes ◽  
...  

Process parameters in Additive Manufacturing (AM) are key factors in the mechanical performance of 3D-printed parts. In order to study their effect, a three-zone model based on the printing pattern was developed. This modelization distinguished three different zones of the 3D-printed part, namely cover, contour, and inner; each zone was treated as a different material. The cover and contour zones were characterized via uniaxial tensile tests and the inner zones via computational homogenization. The model was then validated by means of bending tests and their corresponding computational simulations. To reduce the number of required characterization experiments, a relationship between the raw and 3D-printed material was established by dimensional analysis. This allowed describing the mechanical properties of the printed part with a reduced set of the most influential non-dimensional relationships. The influence on the performance of the parts of inter-layer adhesion was also addressed in this work via the characterization of samples made of Polycarbonate Acrylonitrile Butadiene Styrene (ABS/PC), a polymeric material well known for its poor adhesion strength. It was concluded that by using this approach, the number of required testing configurations could be reduced by two thirds, which implies considerable cost savings.

2019 ◽  
Vol 3 (2) ◽  
pp. 49 ◽  
Author(s):  
Gerardo A. Mazzei Capote ◽  
Alec Redmann ◽  
Tim A. Osswald

Fused Filament Fabrication (FFF) is arguably the most widely available additive manufacturing technology at the moment. Offering the possibility of producing complex geometries in a compressed product development cycle and in a plethora of materials, it has gradually started to become attractive to multiple industrial segments, slowly being implemented in diverse applications. However, the high anisotropy of parts developed through this technique renders failure prediction difficult. The proper performance of the part, or even the safety of the final user, cannot be guaranteed under demanding mechanical requirements. This problem can be tackled through the development of a failure envelope that allows engineers to predict failure by using the knowledge of the stress state of the part. Previous research by the authors developed a failure envelope for acrylonitrile butadiene styrene (ABS) based, Fused Filament Fabrication (FFF) parts by use of a criterion that incorporates stress interactions. This work validates the first quadrant of the envelope by performing uniaxial tensile tests with coupons produced with a variety of raster angles, creating a combined loading stress state in the localized coordinate system. Results show the safe zone encompassed by the failure envelope proved adequate.


Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3669
Author(s):  
Giovanni Gómez-Gras ◽  
Manuel D. Abad ◽  
Marco A. Pérez

Additive manufacturing has experienced remarkable growth in recent years due to the customisation, precision, and cost savings compared to conventional manufacturing techniques. In parallel, materials with great potential have been developed, such as PC-ISO polycarbonate, which has biocompatibility certifications for use in the biomedical industry. However, many of these synthetic materials are not capable of meeting the mechanical stresses to which the biological structure of the human body is naturally subjected. In this study, an exhaustive characterisation of the PC-ISO was carried out, including an investigation on the influence of the printing parameters by fused filament fabrication on its mechanical behaviour. It was found that the effect of the combination of the printing parameters does not have a notable impact on the mass, cost, and manufacturing time of the specimens; however, it is relevant when determining the tensile, bending, shear, impact, and fatigue strengths. The best combinations for its application in biomechanics are proposed, and the need to combine PC-ISO with other materials to achieve the necessary strengths for functioning as a bone scaffold is demonstrated.


Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1589 ◽  
Author(s):  
Nectarios Vidakis ◽  
Markos Petousis ◽  
Athena Maniadi ◽  
Emmanuel Koudoumas ◽  
Marco Liebscher ◽  
...  

In order to enhance the mechanical performance of three-dimensional (3D) printed structures fabricated via commercially available fused filament fabrication (FFF) 3D printers, novel nanocomposite filaments were produced herein following a melt mixing process, and further 3D printed and characterized. Titanium Dioxide (TiO2) and Antimony (Sb) doped Tin Oxide (SnO2) nanoparticles (NPs), hereafter denoted as ATO, were selected as fillers for a polymeric acrylonitrile butadiene styrene (ABS) thermoplastic matrix at various weight % (wt%) concentrations. Tensile and flexural test specimens were 3D printed, according to international standards. It was proven that TiO2 filler enhanced the overall tensile strength by 7%, the flexure strength by 12%, and the micro-hardness by 6%, while for the ATO filler, the corresponding values were 9%, 13%, and 6% respectively, compared to unfilled ABS. Atomic force microscopy (AFM) revealed the size of TiO2 (40 ± 10 nm) and ATO (52 ± 11 nm) NPs. Raman spectroscopy was performed for the TiO2 and ATO NPs as well as for the 3D printed nanocomposites to verify the polymer structure and the incorporated TiO2 and ATO nanocrystallites in the polymer matrix. The scope of this work was to fabricate novel nanocomposite filaments using commercially available materials with enhanced overall mechanical properties that industry can benefit from.


Inventions ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Asahi Yonezawa ◽  
Akira Yamada

Poly(lactic acid) (PLA) is a biodegradable polymer material used for the fabrication of objects by fused filament fabrication (FFF) 3D printing. FFF 3D printing technology has been quickly spreading over the past few years. An FFF-3D-printed object is formed from melted polymer extruded from a nozzle layer-by-layer. The mechanical properties of the object, and the changes in those properties as the object degrades, differ from the properties and changes observed in bulk objects. In this study we evaluated FFF-3D-printed objects by uniaxial tensile tests and four-point flexural tests to characterize the changes of three mechanical properties, namely, the maximum stress, elastic modulus, and breaking energy. Eight types of test pieces printed directly by an FFF 3D printer using two scan patterns and two interior fill percentages (IFPs) were tested by the aforesaid methods. The test pieces were immersed in saline and kept in an incubator at 37 °C for 30, 60, or 90 days before the mechanical testing. The changes in the mechanical properties differed largely between the test piece types. In some of the test pieces, transient increases in strength were observed before the immersion degraded the strength. Several of the test piece types were found to have superior specific strength in the tests. The results obtained in this research will be helpful for the design of PLA structures fabricated by FFF 3D printing.


2021 ◽  
Vol 5 (2) ◽  
pp. 62
Author(s):  
Michel Theodor Mansour ◽  
Konstantinos Tsongas ◽  
Dimitrios Tzetzis

The mechanical properties of Fused Filament Fabrication (FFF) 3D printed specimens of acrylonitrile butadiene styrene (ABS), ABS reinforced with carbon fibers (ABS/CFs) and ABS reinforced with carbon nanotubes (ABS/CNTs) are investigated in this paper using various experimental tests. In particular, the mechanical performance of the fabricated specimens was determined by conducting compression and cyclic compression testing, as well as nanoindentation tests. In addition, the design and the manufacturing of hierarchical honeycomb structures are presented using the materials under study. The 3D printed honeycomb structures were examined by uniaxial compressive tests to review the mechanical behavior of such cellular structures. The compressive performance of the hierarchical honeycomb structures was also evaluated with finite element analysis (FEA) in order to extract the stress-strain response of these structures. The results revealed that the 2nd order hierarchy displayed increased stiffness and strength as compared with the 0th and the 1st hierarchies. Furthermore, the addition of carbon fibers in the ABS matrix improved the stiffness, the strength and the hardness of the FFF printed specimens as well as the compression performance of the honeycomb structures.


2020 ◽  
Vol 318 ◽  
pp. 01049
Author(s):  
Michel Theodor Mansour ◽  
Konstantinos Tsongas ◽  
Dimitris Tzetzis

The aim of this paper is to design hierarchical honeycombs as well as manufacturing such structures with a commercial 3D Printer using Fused Filament Fabrication (FFF) technique. The materials under study are commercial filaments such as acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene/carbon fibers (ABS/CF) and acrylonitrile butadiene styrene/carbon nanotubes (ABS/CNTs). The fabricated hierarchical honeycombs were examined by compression tests in order to evaluate the mechanical behaviour of such honeycomb 3D printed structures. The compression behaviour of the hierarchical honeycombs was assessed also with finite element analysis (FEA) and at the end there was a comparison with the experimental findings. The results reveal that the 2nd order hierarchy presented an increase both in stiffness and strength in comparison with the 0th and the 1st hierarchies which make such designs a suitable for structures require such properties. Also, the results reveal that ABS/carbon fiber constructs outperform the other materials under study.


Computers ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 19
Author(s):  
Sidonie F. Costa ◽  
Fernando M. Duarte ◽  
José A. Covas

Additive Manufacturing Techniques such as Fused Filament Fabrication (FFF) produce 3D parts with complex geometries directly from a computer model without the need of using molds and tools, by gradually depositing material(s), usually in layers. Due to the rapid growth of these techniques, researchers have been increasingly interested in the availability of strategies, models or data that may assist process optimization. In fact, 3D printed parts often exhibit limited mechanical performance, which is usually the result of poor bonding between adjacent filaments. In turn, the latter is influenced by the temperature field history during deposition. This study aims at evaluating the influence of the phase change from the melt to the solid state undergone by semi-crystalline polymers such as Polylactic Acid (PLA), on the heat transfer during the deposition stage. The energy equation considering solidification is solved analytically and then inserted into a MatLab® code to model cooling in FFF. The deposition and cooling of simple geometries is studied first, in order to assess the differences in cooling of amorphous and semi-crystalline polymers. Acrylonitrile Butadiene Styrene (ABS) was taken as representing an amorphous material. Then, the deposition and cooling of a realistic 3D part is investigated, and the influence of the build orientation is discussed.


Author(s):  
Pawan Verma ◽  
Jabir Ubaid ◽  
Andreas Schiffer ◽  
Atul Jain ◽  
Emilio Martínez-Pañeda ◽  
...  

AbstractExperiments and finite element (FE) calculations were performed to study the raster angle–dependent fracture behaviour of acrylonitrile butadiene styrene (ABS) thermoplastic processed via fused filament fabrication (FFF) additive manufacturing (AM). The fracture properties of 3D-printed ABS were characterized based on the concept of essential work of fracture (EWF), utilizing double-edge-notched tension (DENT) specimens considering rectilinear infill patterns with different raster angles (0°, 90° and + 45/− 45°). The measurements showed that the resistance to fracture initiation of 3D-printed ABS specimens is substantially higher for the printing direction perpendicular to the crack plane (0° raster angle) as compared to that of the samples wherein the printing direction is parallel to the crack (90° raster angle), reporting EWF values of 7.24 kJ m−2 and 3.61 kJ m−2, respectively. A relatively high EWF value was also reported for the specimens with + 45/− 45° raster angle (7.40 kJ m−2). Strain field analysis performed via digital image correlation showed that connected plastic zones existed in the ligaments of the DENT specimens prior to the onset of fracture, and this was corroborated by SEM fractography which showed that fracture proceeded by a ductile mechanism involving void growth and coalescence followed by drawing and ductile tearing of fibrils. It was further shown that the raster angle–dependent strength and fracture properties of 3D-printed ABS can be predicted with an acceptable accuracy by a relatively simple FE model considering the anisotropic elasticity and failure properties of FFF specimens. The findings of this study offer guidelines for fracture-resistant design of AM-enabled thermoplastics. Graphical abstract


Technologies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 49
Author(s):  
Alessia Romani ◽  
Andrea Mantelli ◽  
Paolo Tralli ◽  
Stefano Turri ◽  
Marinella Levi ◽  
...  

Fused filament fabrication allows the direct manufacturing of customized and complex products although the layer-by-layer appearance of this process strongly affects the surface quality of the final parts. In recent years, an increasing number of post-processing treatments has been developed for the most used materials. Contrarily to other additive manufacturing technologies, metallization is not a common surface treatment for this process despite the increasing range of high-performing 3D printable materials. The objective of this work is to explore the use of physical vapor deposition sputtering for the chromium metallization of thermoplastic polymers and composites obtained by fused filament fabrication. The thermal and mechanical properties of five materials were firstly evaluated by means of differential scanning calorimetry and tensile tests. Meanwhile, a specific finishing torture test sample was designed and 3D printed to perform the metallization process and evaluate the finishing on different geometrical features. Furthermore, the roughness of the samples was measured before and after the metallization, and a cost analysis was performed to assess the cost-efficiency. To sum up, the metallization of five samples made with different materials was successfully achieved. Although some 3D printing defects worsened after the post-processing treatment, good homogeneity on the finest details was reached. These promising results may encourage further experimentations as well as the development of new applications, i.e., for the automotive and furniture fields.


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