scholarly journals A Computational Geometry Generation Method for Creating 3D Printed Composites and Porous Structures

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2507
Author(s):  
Petros Siegkas
Keyword(s):  
Additive Manufacturing ◽  
Composite Structures ◽  
Thermoplastic Polyurethane ◽  
Voronoi Cell ◽  
Computational Method ◽  
Voronoi Cells ◽  
Potential Applications ◽  
3D Printed ◽  
Manufacturing Methods ◽  
Single Material

A computational method for generating porous materials and composite structures was developed and implemented. The method is based on using 3D Voronoi cells to partition a defined space into segments. The topology of the segments can be controlled by controlling the Voronoi cell set. The geometries can be realized by additive manufacturing methods, and materials can be assigned to each segment. The geometries are generated and processed virtually. The macroscopic mechanical properties of the resulting structures can be tuned by controlling microstructural features. The method is implemented in generating porous and composite structures using polymer filaments i.e., polylactic acid (PLA), thermoplastic polyurethane (TPU) and nylon. The geometries are realized using commercially available double nozzle fusion deposition modelling (FDM) equipment. The compressive properties of the generated porous and composite configurations are tested quasi statically. The structures are either porous of a single material or composites of two materials that are geometrically intertwined. The method is used to produce and explore promising material combinations that could otherwise be difficult to mix. It is potentially applicable with a variety of additive manufacturing methods, size scales, and materials for a range of potential applications.

scholarly journals Recycled Tire Rubber in Additive Manufacturing: Selective Laser Sintering for Polymer-Ground Rubber Composites

2021 ◽  
Vol 11 (18) ◽  
pp. 8778
Author(s):  
Antoniya Toncheva ◽  
Loïc Brison ◽  
Philippe Dubois ◽  
Fouad Laoutid
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Morphological Characteristics ◽  
Laser Sintering ◽  
Industrial Applications ◽  
Tire Rubber ◽  
Abrasive Resistance ◽  
Potential Applications

Natural and synthetic rubber is gaining increased interest in various industrial applications and daily life sectors (automotive industry, acoustic and electrical isolators, adhesives, impermeable surfaces, and others) due to its remarkable physicomechanical properties, excellent durability, and abrasive resistance. These great characteristics are accompanied by some recycling difficulties of the final products, particularly originated from the tire waste rubber industry. In this study, recycled tire rubber was incorporated in polymer matrices using selective laser sintering as 3D printing technology. Two polymers were used-polyamide and thermoplastic polyurethane, for their rigid and elastomeric properties, respectively. Polymer composites containing various tire powder amounts, up to 40 wt.%, were prepared by physical blending. The final materials’ morphological characteristics, mechanical properties, and thermal stability were evaluated. The proposed ambitious additive manufacturing approach looked over also some of the major aspects to be considered during the 3D printing procedure. In addition, examples of printed prototypes with potential applications were also proposed revealing the potential of the recycled tire rubber-loaded composites.

scholarly journals A Soft 3D-Printed Robotic Hand Actuated by Coiled SMA

Actuators ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Eric Deng ◽  
Yonas Tadesse
Keyword(s):  
Additive Manufacturing ◽  
Low Cost ◽  
Thermoplastic Polyurethane ◽  
Average Power ◽  
Robotic Hand ◽  
Custom Made ◽  
3D Printed ◽  
Artificial Hand ◽  
Time Domain Response ◽  
The Time Domain

Robotic hands with unique designs, capabilities and applications have been presented in the literature focusing on sensing, actuation, control, powering and manufacturing, most of which are created by manual assembly process. However, due to advancements in additive manufacturing, new capabilities have replaced traditional methods of manufacturing. In this paper, we present a soft 3D-printed robotic hand actuated by custom-made coiled shape memory alloy (SMA) actuators. The hand uses additive manufacturing of flexible thermoplastic polyurethane (TPU) material, which allows flexing at the joint and hence eliminates the need for additional assembly. Here, we present the full characteristics of the robotic hand such as object grasping categorized by size and weight from the ARAT kit and others. The robotic hand is 425 mm in length, weighs 235 g and is able to operate at a frequency of 0.125 Hz without active cooling. It can grasp an object of 55–81 mm widths, weighing up to 133 g, while consuming an average power of 7.82 W. We also show the time domain response of our custom-made coiled SMA to different current inputs, and its corresponding force and displacement. The current design yields a lightweight and low cost artificial hand with significantly simplified manufacturing for applications in robotics and prosthetics.

Multi-Material Composition Optimization vs Software-Based Single-Material Topology Optimization of a Rectangular Sample under Flexural Load for Fused Deposition Modeling Process

2021 ◽  
Vol 1042 ◽  
pp. 23-44
Author(s):  
Vahid Hassani ◽  
Hamid Ahmad Mehrabi ◽  
Carl Gregg ◽  
Roger William O'Brien ◽  
Iñigo Flores Ituarte ◽  
...  
Keyword(s):  
Fused Deposition Modeling ◽  
Volume Fraction ◽  
Thermoplastic Polyurethane ◽  
Von Mises Stress ◽  
Fused Deposition ◽  
Hard Polymer ◽  
Deposition Modeling ◽  
3D Printed ◽  
Single Material ◽  
Soft Polymers

Additive manufacturing (AM) technologies have been evolved over the last decade, enabling engineers and researchers to improve functionalities of parts by introducing a growing technology known as multi-material AM. In this context, fused deposition modeling (FDM) process has been modified to create multi-material 3D printed objects with higher functionality. The new technology enables it to combine several types of polymers with hard and soft constituents to make a 3D printed part with improved mechanical properties and functionalities. Knowing this capability, this paper aims to present a parametric optimization method using a genetic algorithm (GA) to find the optimum composition of hard polymer as polylactic acid (PLA) and soft polymer as thermoplastic polyurethane (TPU 95A) used in Ultimaker 3D printer for making a rectangular sample under flexural load in order to minimize the von Mises stress as an objective function. These samples are initially presented in four deferent forms in terms of composition of hard and soft polymers and then, after the optimization process, the final ratio of each type of material will be achieved. Based on the volume fraction of soft polymers in each sample, the equivalent topologically-optimized samples will be obtained that are solely made of single-material PLA as hard polymer under the same flexural load as applied to multi-material samples. Finally, the structural results and manufacturability in terms of the generated support structures, as key element of some AM processes, will be compared for the resultant samples created by two methods of optimization.

Production of 3D Printed Flexible Strain Sensors

2020 ◽  
Author(s):  
Trevor Mamer ◽  
Jose Garcia ◽  
Walter D. Leon-Salas ◽  
Richard Voyles ◽  
Robert A. Nawrocki ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Thermoplastic Polyurethane ◽  
Testing Machine ◽  
Dielectric Substrate ◽  
Linear Increase ◽  
Fused Filament Fabrication ◽  
Structured Materials ◽  
Range Function ◽  
Strain Testing ◽  
3D Printed

Abstract 3D printing technologies have advanced significantly in recent years allowing for additive manufacturing of new structured materials, expanding the range, function, and capabilities of manufactured components. In this work, flexible capacitors were produced using additive manufacturing and compared to commercially available capacitance sensors in strain testing. The sensors utilize thermoplastic polyurethane (TPU) printed using fused filament fabrication methods as a dielectric substrate and a combination of flexible inks for production of the conductive surface. Flexible inks were printed using syringe based deposition methods on a custom designed printer using the TPU substrate. Results demonstrated successful capacitor production with capacitance values ranging from 2–70 pF depending on geometry, material, and printing conditions. The 3D printed flexible capacitors were characterized over a frequency range of 100 Hz to 10 kHz and compared to commercial roll-to-roll produced capacitors. Strain testing was conducted from 0–50% strain using a mechanical testing machine for the range of sensors and final capacitance post strain was measured to calculate deviation from original capacitance values. The sensors exhibited a relatively linear increase in capacitance when strained and returned to a resting position upon release of strain with minimal hysteresis effects, demonstrating their utility as 3D printed sensors.

scholarly journals Design and Evaluation of 3D-Printed 4 Structures Coated By CWPU/Graphene as Strain Sensor: Truss, Honeycomb, Chiral Truss, Re-entrant

2021 ◽  
Author(s):  
Hyeong Yeol Choi ◽  
Eun Joo Shin ◽  
Sun Hee Lee
Keyword(s):  
Poisson’S Ratio ◽  
Thermoplastic Polyurethane ◽  
Strain Sensor ◽  
Dip Coating ◽  
Raw Material ◽  
Poisson's Ratio ◽  
Constant Change ◽  
Potential Applications ◽  
Auxetic Structures ◽  
3D Printed

Abstract A strain sensor characterized by elasticity has recently been studied in various ways to be applied to monitoring humans or robots. Here, 4 types of 3D-printed auxetic lattice structures using thermoplastic polyurethane (TPU) as raw material were characterized: truss and honeycomb with positive Poisson's ratio and chiral truss and re-entrant with negative Poisson's ratio. Each structure was fabricated as a flexible and stable strain sensor by coating graphene through a dip-coating process. The fabricated auxetic structures have excellent strength, flexibility, and electrical conductivity desirable for a strain sensor and detect a constant change in resistance at a given strain. The 3D-printed auxetic lattice 4 type structures coated with CWPU/Graphene suggest potential applications of multifunctional strain sensors under deformation.

scholarly journals Comparative investigation on the mechanical behavior of injection molded and 3D-printed thermoplastic polyurethane

2021 ◽  
Author(s):  
Erik Oelsch ◽  
Ralf Landgraf ◽  
Lysander Jankowsky ◽  
Martin Kausch ◽  
Stefan Hoyer ◽  
...  
Keyword(s):  
Injection Molding ◽  
Mechanical Behavior ◽  
Uniaxial Tension ◽  
Thermoplastic Polyurethane ◽  
Material Behavior ◽  
Optical Measurements ◽  
Injection Molding Process ◽  
Inelastic Material ◽  
3D Printed ◽  
Manufacturing Methods

Abstract3D printing opens up new possibilities for the production of polymeric structures that would not be possible with injection molding. However, it is known that the manufacturing method might have an impact on the mechanical properties of manufactured components. To this end, the mechanical behavior of test specimens made of thermoplastic polyurethane is compared for two different manufacturing methods. In particular, the SEAM technology (screw extrusion additive manufacturing) is compared to a conventional injection molding process. Uniaxial tension test specimens from both manufacturing methods are analyzed in two testing sequences (multi-hysteresis tests to analyze inelastic properties and uniaxial tension until rupture). To get as less perturbation as possible, the 3D-printed samples are printed with only one strand per layer. Moreover, a correction approach based on optical measurements is applied to determine the true cross-sectional area of the test specimens. The mechanical tests reveal that the inelastic material behavior is the same for both manufacturing methods. Instead, 3D-printed specimens show lower maximal stretch values at rupture and an increased variance in the results, which is related to the surface structure of 3D-printed specimens.

AM-Serienproduktion für die Automobilindustrie/AM series production for the automotive industry

2020 ◽  
Vol 110 (11-12) ◽  
pp. 752-757
Author(s):  
Lukas Weiser ◽  
Marco Batschkowski ◽  
Niclas Eschner ◽  
Benjamin Häfner ◽  
Ingo Neubauer ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Automotive Industry ◽  
Series Production ◽  
Production Scale ◽  
Additive Fertigung ◽  
Small Series ◽  
Start Up ◽  
3D Printed ◽  
Component Quality

Die additive Fertigung schafft neue Gestaltungsfreiheiten. Im Rahmen des Prototypenbaus und der Kleinserienproduktion kann das Verfahren des selektiven Laserschmelzens genutzt werden. Die Verwendung in der Serienproduktion ist bisher aufgrund unzureichender Bauteilqualität, langen Anlaufzeiten sowie mangelnder Automatisierung nicht im wirtschaftlichen Rahmen möglich. Das Projekt „ReAddi“ möchte eine erste prototypische Serienfertigung entwickeln, mit der additiv gefertigte Bauteile für die Automobilindustrie wirtschaftlich produziert werden können. Additive manufacturing (AM) offers new freedom of design. The selective laser-powderbed fusion (L-PBF) process can be used for prototyping and small series production. So far, it has not been economical to use it on a production scale due to insufficient component quality, long start-up times and a lack of automation. The project ReAddi aims to develop a first prototype series production to cost-effectively manufacture 3D-printed components for the automotive industry.

scholarly journals Current and Potential Applications of Additive Manufacturing for Power Electronics

2021 ◽  
Vol 2 ◽  
pp. 33-42
Author(s):  
Luis Lopera ◽  
Romina Rodriguez ◽  
Mostafa Yakout ◽  
Mo Elbestawi ◽  
Ali Emadi
Keyword(s):  
Additive Manufacturing ◽  
Power Electronics ◽  
Potential Applications
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