scholarly journals Mechanical Performance of 3D-Printed Biocompatible Polycarbonate for Biomechanical Applications

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 ◽  
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.


Fibers ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 74
Author(s):  
Nectarios Vidakis ◽  
Markos Petousis ◽  
Emmanouil Velidakis ◽  
Mariza Spiridaki ◽  
John D. Kechagias

In this study, nanocomposites were fabricated with polycarbonate (PC) as the matrix material. Cellulose Nanofiber (CNF) at low filler loadings (0.5 wt.% and 1.0 wt.%) was used as the filler. Samples were produced using melt mixing extrusion with the Fused Filament Fabrication (FFF) process. The optimum 3D-printing parameters were experimentally determined and the required specimens for each tested material were manufactured using FFF 3D printing. Tests conducted for mechanical performance were tensile, flexural, impact, and Dynamic Mechanical Analysis (DMA) tests, while images of the side and the fracture area of the specimens were acquired using Scanning Electron Microscopy (SEM), aiming to determine the morphology of the specimens and the fracture mechanism. It was concluded that the filler’s ratio addition of 0.5 wt.% created the optimum performance when compared to pure PC and PC CNF 1.0 wt.% nanocomposite material.


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.


2019 ◽  
Vol 25 ◽  
pp. 52-57
Author(s):  
Eva Heiml ◽  
Anna Kalteis ◽  
Zoltan Major

Lattice structures are currently of high interest, especially for lightweight design. They generally have better structural performance per weight than parts made of bulk material. With conventional manufacturing techniques they are difficult to produce, but with additive manufacturing (AM) fabricationisfeasible. To better understand their behaviour under various loading conditions two lattice structures in different configurations were observed. For each structure three different test specimens were designed and manufactured using selective laser sintering (SLS). To investigate the mechanical performance under large deformations the specimens were made of a thermoplastic polyurethane(TPU), which shows a hyperelastic material behaviour. Beside the experimental observations also finite element analyses (FEA) were conducted to investigate the deformation behaviour in more detail.


2016 ◽  
Vol 853 ◽  
pp. 394-398 ◽  
Author(s):  
M.G. Rashed ◽  
Mahmud Ashraf ◽  
Paul Jonathan Hazell

Although metallic microlattice material is a sought after research topic currently, it suffers from manufacturing defects such as micro-voids formation due to missed fusion, stemmed from the stacking-layered-fused nature of the metal powder in Powder Bed Fusion (PBF) process. These defects result in weakening of the finished part and reduced mechanical performance under service load, possibly leading to low fatigue strength, and raise serious question about 3D printed structural integrity. Numerical simulation of the built parts also becomes difficult due to irregular physical properties including geometry and anisotropic nature of mechanical properties. This paper provides an overview on the manufacturing issues and the subsequent hurdle faced in numerical simulation of metallic microlattices. While the issues in manufacturing are related to emerging additive manufacturing techniques and out of control of end users, it has been suggested that the limitations in numerical simulation can be overcome by employing advanced approaches, in both physical properties measurement and modeling.


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.


Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2524
Author(s):  
Ilaria Papa ◽  
Alessia Teresa Silvestri ◽  
Maria Rosaria Ricciardi ◽  
Valentina Lopresto ◽  
Antonino Squillace

Among the several additive manufacturing techniques, fused filament fabrication (FFF) is a 3D printing technique that is fast, handy, and low cost, used to produce complex-shaped parts easily and quickly. FFF adds material layer by layer, saving energy, costs, raw material costs, and waste. Nevertheless, the mechanical properties of the thermoplastic materials involved are low compared to traditional engineering materials. This paper deals with the manufacturing of composite material laminates obtained by the Markforged continuous filament fabrication (CFF) technique, using an innovative matrix infilled by carbon nanofibre (Onyx), a high-strength thermoplastic material with an excellent surface finish and high resistance to chemical agents. Three macro-categories of samples were manufactured using Onyx and continuous carbon fibre to evaluate the effect of the fibre on mechanical features of the novel composites and their influence on surface finishes. SEM (Scanning Electron Microscopy) analysis and acquisition of roughness profile by a confocal lens were conducted. Tensile and compression tests, thermogravimetric analysis and calorimetric analysis using a DSC (differential scanning calorimeter) were carried out on all specimen types to evaluate the influence of the process parameters and layup configurations on the quality and mechanical behaviour of the 3D-printed samples.


2019 ◽  
Vol 25 (6) ◽  
pp. 972-988 ◽  
Author(s):  
Isaac Ferreira ◽  
Margarida Machado ◽  
Fernando Alves ◽  
António Torres Marques

Purpose In industry, fused filament fabrication (FFF) offers flexibility and agility by promoting a reduction in costs and in the lead-time (i.e. time-to-market). Nevertheless, FFF parts exhibit some limitations such as lack of accuracy and/or lower mechanical performance. As a result, some alternatives have been developed to overcome some of these restrictions, namely, the formulation of high performance polymers, the creation of fibre-reinforced materials by FFF process and/or the design of new FFF-based technologies for printing composite materials. This work aims to analyze these technologies. Design/methodology/approach This work aims to study and understand the advances in the behaviour of 3D printed parts with enhanced performance by its reinforcement with several shapes and types of fibres from nanoparticles to continuous fibre roving. Thus, a comprehensive survey of significant research studies carried out regarding FFF of fibre-reinforced thermoplastics is provided, giving emphasis to the most relevant and innovative developments or adaptations undergone at hardware level and/or on the production process of the feedstock. Findings It is shown that the different types of reinforcement present different challenges for the printing process with different outcomes in the part performance. Originality/value This review is focused on joining the most important researches dedicated to the process of FFF-printed parts with different types reinforcing materials. By dividing the reinforcements in categories by shape/geometry and method of processing, it is possible to better quantify performance improvements.


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