scholarly journals Deposition of Biocompatible Polymers by 3D Printing (FDM) on Titanium Alloy

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 235
Author(s):  
Dominika Grygier ◽  
Maciej Kujawa ◽  
Piotr Kowalewski
Keyword(s):  
Titanium Alloy ◽  
Friction Coefficient ◽  
3D Printing ◽  
Biocompatible Polymers ◽  
Lubrication Mechanism ◽  
Shear Tests ◽  
Ti6al4v Titanium Alloy ◽  
Strength Tests ◽  
3D Printed ◽  
Metal Polymer

Nowadays, the replacement of a hip joint is a standard surgical procedure. However, researchers have continuingly been trying to upgrade endoprostheses and make them more similar to natural joints. The use of 3D printing could be helpful in such cases, since 3D-printed elements could mimic the natural lubrication mechanism of the meniscus. In this paper, we propose a method to deposit plastics directly on titanium alloy using 3D printing (FDM). This procedure allows one to obtain endoprostheses that are more similar to natural joints, easier to manufacture and have fewer components. During the research, biocompatible polymers suitable for 3D FDM printing were used, namely polylactide (PLA) and polyamide (PA). The research included tensile and shear tests of metal–polymer bonds, friction coefficient measurements and microscopic observations. The friction coefficient measurements revealed that only PA was promising for endoprostheses (the friction coefficient for PLA was too high). The strength tests and microscopic observations showed that PLA and PA deposition by 3D FDM printing directly on Ti6Al4V titanium alloy is possible; however, the achieved bonding strength and repeatability of the process were unsatisfactory. Nevertheless, the benefits arising from application of this method mean that it is worthwhile to continue working on this issue.

Thermal Conductivity Testing Apparatus for 3D Printed Materials

2017 ◽  
Author(s):  
Tiffaney Flaata ◽  
Gregory J. Michna ◽  
Todd Letcher
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Polymer Composite ◽  
Heat Exchangers ◽  
Fused Deposition ◽  
3D Printed ◽  
Printed Materials ◽  
Metal Polymer

Additive manufacturing, the layer-by-layer creation of parts, was initially used for rapid prototyping of new designs. Recently, due to the decrease in the cost and increase in the resolution and strength of additively manufactured parts, additive manufacturing is increasingly being used for production of parts for end-use applications. Fused Deposition Modeling (FDM), a type of 3d printing, is a process of additive manufacturing in which a molten thermoplastic material is extruded to create the desired geometry. Many potential heat transfer applications of 3d printed parts, including the development of additively manufactured heat exchangers, exist. In addition, the availability of metal/polymer composite filaments, first used for applications such as tooling for injection molding applications and to improve wear resistance, could lead to increased performance 3d printed heat exchangers because of the higher thermal conductivity of the material. However, the exploitation of 3d printing for heat transfer applications is hindered by a lack of reliable thermal conductivity data for as-printed materials, which typically include significant void fractions. In this experimental study, an apparatus to measure the effective thermal conductivity of 3d printed composite materials was designed and fabricated. Its ability to accurately measure the thermal conductivity of polymers was validated using a sample of acrylic, whose conductivity is well understood. Finally, the thermal conductivities of various 3d printed polymer, metal/polymer composite, and carbon/polymer composite filaments were measured and are reported in this paper. The materials used are acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), stainless steel/PLA, Brass/PLA, and Bronze/PLA.

scholarly journals Frictional Anisotropy of 3D-Printed Fault Surfaces

2021 ◽  
Vol 9 ◽  
Author(s):  
Tom Vincent-Dospital ◽  
Alain Steyer ◽  
François Renard ◽  
Renaud Toussaint
Keyword(s):  
Friction Coefficient ◽  
3D Printing ◽  
Mechanical Stability ◽  
Spatial Scales ◽  
Static Friction ◽  
Spatial Anisotropy ◽  
Frictional Properties ◽  
Average Coefficient ◽  
3D Printed ◽  
Frictional Slip

The surface morphology of faults controls the spatial anisotropy of their frictional properties and hence their mechanical stability. Such anisotropy is only rarely studied in seismology models of fault slip, although it might be paramount to understand the seismic rupture in particular areas, notably where slip occurs in a direction different from that of the main striations of the fault. To quantify how the anisotropy of fault surfaces affects the friction coefficient during sliding, we sheared synthetic fault planes made of plaster of Paris. These fault planes were produced by 3D-printing real striated fault surfaces whose 3D roughness was measured in the field at spatial scales from millimeters to meters. Here, we show how the 3D-printing technology can help for the study of frictional slip. The results show that fault anisotropy controls the coefficient of static friction, with μS//, the friction coefficient along the striations being three to four times smaller than μS⊥, the friction coefficient along the orientation perpendicular to the striations. This is true both at the meter and the millimeter scales. The anisotropy in friction and the average coefficient of static friction are also shown to decrease with the normal stress applied to the faults, as a result of the increased surface wear under increased loading.

scholarly journals AN INVESTIGATION OF THE STRUCTURAL STRENGTH OF TRANSTIBIAL SOCKETS FABRICATED USING CONVENTIONAL METHODS AND RAPID PROTOTYPING TECHNIQUES

2019 ◽  
Author(s):  
Brittany Pousett ◽  
Aimee Lizcano ◽  
Silvia Ursula Raschke
Keyword(s):  
3D Printing ◽  
Rapid Prototyping ◽  
Ultimate Strength ◽  
Stance Phase ◽  
Structural Strength ◽  
Static Strength ◽  
Strength Test ◽  
Manufacturing Method ◽  
Strength Tests ◽  
3D Printed

BACKGROUND: Rapid Prototyping is becoming an accessible manufacturing method but before clinical adoption can occur, the safety of treatments needs to be established. Previous studies have evaluated the static strength of traditional sockets using ultimate strength testing protocols outlined by the International Organization for Standardization (ISO). OBJECTIVE: To carry out a pilot test in which 3D printed sockets will be compared to traditionally fabricated sockets, by applying a static ultimate strength test. METHODOLOGY: 36 sockets were made from a mold of a transtibial socket shape,18 for cushion liners with a distal socket attachment block and 18 for locking liners with a distal 4-hole pattern. Of the 18 sockets, 6 were thermoplastic, 6 laminated composites & 6 3D printed Polylactic Acid. Sockets were aligned in standard bench alignment and placed in a testing jig that applied forces simulating individuals of different weight putting force through the socket both early and late in the stance phase. Ultimate strength tests were conducted in these conditions. If a setup passed the ultimate strength test, load was applied until failure. FINDINGS: All sockets made for cushion liners passed the strength tests, however failure levels and methods varied. For early stance, thermoplastic sockets yielded, laminated sockets cracked posteriorly, and 3D printed socket broke circumferen-tially. For late stance, 2/3 of the sockets failed at the pylon. Sockets made for locking liners passed the ultimate strength tests early in stance phase, however, none of the sockets passed for forces late in stance phase, all broke around the lock mechanism.  CONCLUSION: Thermoplastic, laminated and 3D printed sockets made for cushion liners passed the ultimate strength test protocol outlined by the ISO for forces applied statically in gait. This provides initial evidence that 3D printed sockets are statically safe to use on patients and quantifies the static strength of laminated and thermoplastic sockets. However, all set-ups of sockets made for locking liners failed at terminal stance. While further work is needed, this suggests that the distal reinforcement for thermoplastic, laminated and 3D printed sockets with distal cylindrical locks may need to be reconsidered. LAYMAN’S ABSTRACT 3D printing is a new manufacturing method that could be used to make prosthetic sockets (the part of the prosthesis connected to the individual). However, very little is known about the strength of 3D printed sockets and if they are safe to use. As Prosthetists are responsible for providing patients with safe treatments, the strength of 3D printed sockets needs to be established before they can be used in clinical practice. The strength of sockets made using current manufacturing methods was compared to those made using 3D printing. Strength was tested using the static portion of the ISO standard most applicable for this situation which outlines the forces a socket must take at 2 points in walking–when the foot is placed on the ground (early stance) and when the foot pushed off the ground (late stance). Sockets made for two prosthetic designs (cushion and locking) were tested to determine if one is safer than the other. All sockets made for cushion liners passed the standard for forces applied statically. However, different materials failed in different ways. At early stance, thermoplastic sockets yielded, laminated composite sockets cracked and 3D printed sockets broke circumferentially. At late stance other components failed 2/3 of the time before the sockets were affected. This provides initial evidence that sockets made for cushion liners are statically safe to use on patients. Sockets made for locking liners failed around the end, showing that 3D printing should not be used to create sockets with the design tested in this study. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/31008/24937 How to Cite: Pousett B, Lizcano A, Raschke S.U. An investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. Canadian Prosthetics & Orthotics Journal. 2019; Volume2, Issue1, No.2. DOI: https://doi.org/10.33137/cpoj.v2i1.31008 CORRESPONDING AUTHORBrittany Pousett, BSc, MSc, Certified Prosthetist,Head of Research at Barber Prosthetics Clinic,540 SE Marine Dr, Vancouver, British Colombia V5X 2T4, Canada.Email: [email protected]

Metallographic and Fractographic Evaluation of 3D-Printed Titanium Samples to Eliminate Unsatisfactory Mechanical Properties

2017 ◽  
Vol 270 ◽  
pp. 212-217
Author(s):  
Michaela Fousová ◽  
Tereza Stejskalova ◽  
Dalibor Vojtěch
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
3D Printing ◽  
Process Parameters ◽  
Patient Specific ◽  
Medical Implants ◽  
Laser Melting ◽  
Patient Specific Implants ◽  
3D Printed ◽  
Set Up

Czech company ProSpon spol. s r.o. has introduced 3D printing technology in its production in 2015. This company operates in the field of development, manufacture and distribution of medical implants and instruments for orthopedics, traumatology and surgery. Therefore, the current intention is to employ Selective Laser Melting (SLM) technology for production of complex and patient-specific implants from titanium alloy Ti-6Al-4V. Nevertheless, first series of produced test specimens suffered from very low plasticity insufficient for the intended application. The reduction in elongation was almost 7fold compared to conventionally used wrought standard. From that reason, specimens were subjected to fractographic evaluation of fracture surfaces, but also metallographic evaluation. The main cause of the identified problem turned out to be porosity originating from inappropriate set-up of the machine. After the adjustment of process parameters new series of specimens were prepared in which the porosity was already significantly lower. Consequently, mechanical properties reached higher and better values.

scholarly journals Embedding Ultra-High-Molecular-Weight Polyethylene Fibers in 3D-Printed Polylactic Acid (PLA) Parts

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1825 ◽  
Author(s):  
Amza ◽  
Zapciu ◽  
Eyþórsdóttir ◽  
Björnsdóttir ◽  
Borg
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
3D Printing ◽  
High Molecular Weight ◽  
Polylactic Acid ◽  
Strength Tests ◽  
Raster Angle ◽  
Uhmwpe Fibers ◽  
3D Printed ◽  
Ultra High Molecular Weight

This study aims to assess whether ultra-high-molecular-weight polyethylene (UHMWPE) fibers can be successfully embedded in a polylactic acid (PLA) matrix in a material extrusion 3D printing (ME3DP) process, despite the apparent thermal incompatibility between the two materials. The work started with assessing the maximum PLA extrusion temperatures at which UHMWPE fibers withstand the 3D printing process without melting or severe degradation. After testing various fiber orientations and extrusion temperatures, it has been found that the maximum extrusion temperature depends on fiber orientation relative to extrusion pathing and varies between 175 °C and 185 °C at an ambient temperature of 25 °C. Multiple specimens with embedded strands of UHMWPE fibers have been 3D printed and following tensile strength tests on the fabricated specimens, it has been found that adding even a small number of fiber strands laid in the same direction as the load increased tensile strength by 12% to 23% depending on the raster angle, even when taking into account the decrease in tensile strength due to reduced performance of the PLA substrate caused by lower extrusion temperatures.

A Quantitative Theory for the Computation of Tire Friction Under Severe Conditions of Sliding

1986 ◽  
Vol 14 (1) ◽  
pp. 44-72 ◽  
Author(s):  
C. M. Mc C. Ettles
Keyword(s):  
Friction Coefficient ◽  
Flash Temperature ◽  
Contact Conditions ◽  
Quantitative Form ◽  
Heating Effects ◽  
Rubber Friction ◽  
Viscoelastic Effects ◽  
Tire Friction ◽  
Pavement Friction ◽  
Metal Polymer

Abstract It is proposed that tire-pavement friction is controlled by thermal rather than by hysteresis and viscoelastic effects. A numerical model of heating effects in sliding is described in which the friction coefficient emerges as a dependent variable. The overall results of the model can be expressed in a closed form using Blok's flash temperature theory. This allows the factors controlling rubber friction to be recognized directly. The model can be applied in quantitative form to metal-polymer-ice contacts. Several examples of correlation are given. The difficulties of characterizing the contact conditions in tire-pavement friction reduce the model to qualitative form. Each of the governing parameters is examined in detail. The attainment of higher friction by small, discrete particles of aluminum filler is discussed.

Biodegradable 3D Printed Polymer Microneedles for Transdermal Drug Delivery

2018 ◽  
Author(s):  
Michael A. Luzuriaga ◽  
Danielle R. Berry ◽  
John C. Reagan ◽  
Ronald A. Smaldone ◽  
Jeremiah J. Gassensmith
Keyword(s):  
Drug Delivery ◽  
3D Printing ◽  
Transdermal Drug Delivery ◽  
Fused Deposition Modeling ◽  
Fused Deposition ◽  
Modeling Software ◽  
Deposition Modeling ◽  
3D Printed ◽  
Microfabrication Technique ◽  
Mechanical Strengths

Biodegradable polymer microneedle (MN) arrays are an emerging class of transdermal drug delivery devices that promise a painless and sanitary alternative to syringes; however, prototyping bespoke needle architectures is expensive and requires production of new master templates. Here, we present a new microfabrication technique for MNs using fused deposition modeling (FDM) 3D printing using polylactic acid, an FDA approved, renewable, biodegradable, thermoplastic material. We show how this natural degradability can be exploited to overcome a key challenge of FDM 3D printing, in particular the low resolution of these printers. We improved the feature size of the printed parts significantly by developing a post fabrication chemical etching protocol, which allowed us to access tip sizes as small as 1 μm. With 3D modeling software, various MN shapes were designed and printed rapidly with custom needle density, length, and shape. Scanning electron microscopy confirmed that our method resulted in needle tip sizes in the range of 1 – 55 µm, which could successfully penetrate and break off into porcine skin. We have also shown that these MNs have comparable mechanical strengths to currently fabricated MNs and we further demonstrated how the swellability of PLA can be exploited to load small molecule drugs and how its degradability in skin can release those small molecules over time.

Biomimetic Design of 3D Printed Tissue-engineered bone Constructs

2020 ◽  
Vol 16 ◽  
Author(s):  
Wei Liu ◽  
Shifeng Liu ◽  
Yunzhe Li ◽  
Peng Zhou ◽  
Qian ma
Keyword(s):  
Tissue Engineering ◽  
3D Printing ◽  
Advanced Materials ◽  
Bionic Design ◽  
Material Interfaces ◽  
Precise Control ◽  
Cell Printing ◽  
Biomimetic Scaffolds ◽  
3D Printed

Abstract:: Surgery to repair damaged tissue, which is caused by disease or trauma, is being carried out all the time, and a desirable treatment is compelling need to regenerate damaged tissues to further improve the quality of human health. Therefore, more and more research focus on exploring the most suitable bionic design to enrich available treatment methods. 3D-printing, as an advanced materials processing approach, holds promising potential to create prototypes with complex constructs that could reproduce primitive tissues and organs as much as possible or provide appropriate cell-material interfaces. In a sense, 3D printing promises to bridge between tissue engineering and bionic design, which can provide an unprecedented personalized recapitulation with biomimetic function under the precise control of the composition and spatial distribution of cells and biomaterials. This article describes recent progress in 3D bionic design and the potential application prospect of 3D printing regenerative medicine including 3D printing biomimetic scaffolds and 3D cell printing in tissue engineering.

scholarly journals Design of a 3D-printed hand prosthesis featuring articulated bio-inspired fingers

2020 ◽  
pp. 095441192098088
Author(s):  
Juan Sebastian Cuellar ◽  
Dick Plettenburg ◽  
Amir A Zadpoor ◽  
Paul Breedveld ◽  
Gerwin Smit
Keyword(s):  
3D Printing ◽  
Design Principles ◽  
Prosthetic Hand ◽  
Hand Prosthesis ◽  
Fused Deposition ◽  
Pinch Force ◽  
Actuation System ◽  
3D Printed ◽  
Energy Dissipated ◽  
Dual Material

Various upper-limb prostheses have been designed for 3D printing but only a few of them are based on bio-inspired design principles and many anatomical details are not typically incorporated even though 3D printing offers advantages that facilitate the application of such design principles. We therefore aimed to apply a bio-inspired approach to the design and fabrication of articulated fingers for a new type of 3D printed hand prosthesis that is body-powered and complies with basic user requirements. We first studied the biological structure of human fingers and their movement control mechanisms in order to devise the transmission and actuation system. A number of working principles were established and various simplifications were made to fabricate the hand prosthesis using a fused deposition modelling (FDM) 3D printer with dual material extrusion. We then evaluated the mechanical performance of the prosthetic device by measuring its ability to exert pinch forces and the energy dissipated during each operational cycle. We fabricated our prototypes using three polymeric materials including PLA, TPU, and Nylon. The total weight of the prosthesis was 92 g with a total material cost of 12 US dollars. The energy dissipated during each cycle was 0.380 Nm with a pinch force of ≈16 N corresponding to an input force of 100 N. The hand is actuated by a conventional pulling cable used in BP prostheses. It is connected to a shoulder strap at one end and to the coupling of the whiffle tree mechanism at the other end. The whiffle tree mechanism distributes the force to the four tendons, which bend all fingers simultaneously when pulled. The design described in this manuscript demonstrates several bio-inspired design features and is capable of performing different grasping patterns due to the adaptive grasping provided by the articulated fingers. The pinch force obtained is superior to other fully 3D printed body-powered hand prostheses, but still below that of conventional body powered hand prostheses. We present a 3D printed bio-inspired prosthetic hand that is body-powered and includes all of the following characteristics: adaptive grasping, articulated fingers, and minimized post-printing assembly. Additionally, the low cost and low weight make this prosthetic hand a worthy option mainly in locations where state-of-the-art prosthetic workshops are absent.

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