scholarly journals Selective Laser Sintering Fabricated Thermoplastic Polyurethane/Graphene Cellular Structures with Tailorable Properties and High Strain Sensitivity

2019 ◽  
Vol 9 (5) ◽  
pp. 864 ◽  
Author(s):  
Alfredo Ronca ◽  
Gennaro Rollo ◽  
Pierfrancesco Cerruti ◽  
Guoxia Fei ◽  
Xinpeng Gan ◽  
...  
Keyword(s):  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Gauge Factor ◽  
Strain Sensitivity ◽  
Porous Structures ◽  
Compression Tests ◽  
Triply Periodic ◽  
Unit Cells

Electrically conductive and flexible thermoplastic polyurethane/graphene (TPU/GE) porous structures were successfully fabricated by selective laser sintering (SLS) technique starting from graphene (GE)-wrapped thermoplastic polyurethane (TPU) powders. Several 3D mathematically defined architectures, with porosities from 20% to 80%, were designed by using triply periodic minimal surfaces (TMPS) equations corresponding to Schwarz (S), Diamond (D), and Gyroid (G) unit cells. The resulting three-dimensional porous structures exhibit an effective conductive network due to the segregation of graphene nanoplatelets previously assembled onto the TPU powder surface. GE nanoplatelets improve the thermal stability of the TPU matrix, also increasing its glass transition temperature. Moreover, the porous structures realized by S geometry display higher elastic modulus values in comparison to D and G-based structures. Upon cyclic compression tests, all porous structures exhibit a robust negative piezoresistive behavior, regardless of their porosity and geometry, with outstanding strain sensitivity. Gauge factor (GF) values of 12.4 at 8% strain are achieved for S structures at 40 and 60% porosity, and GF values up to 60 are obtained for deformation extents lower than 5%. Thermal conductivity of the TPU/GE structures significantly decreases with increasing porosity, while the effect of the structure architecture is less relevant. The TPU/GE porous structures herein reported hold great potential as flexible, highly sensitive, and stable strain sensors in wearable or implantable devices, as well as dielectric elastomer actuators.

scholarly journals On the Synergistic Effect of Multi-Walled Carbon Nanotubes and Graphene Nanoplatelets to Enhance the Functional Properties of SLS 3D-Printed Elastomeric Structures

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1841 ◽  
Author(s):  
Gennaro Rollo ◽  
Alfredo Ronca ◽  
Pierfrancesco Cerruti ◽  
Xin Peng Gan ◽  
Guoxia Fei ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Functional Properties ◽  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Gauge Factor ◽  
Porous Structures ◽  
Elastomeric Matrix ◽  
Unit Cells ◽  
Multi Walled Carbon Nanotubes ◽  
Electro Magnetic

Elastomer-based porous structures realized by selective laser sintering (SLS) are emerging as a new class of attractive multifunctional materials. Herein, a thermoplastic polyurethane (TPU) powder for SLS was modified by 1 wt.% multi-walled carbon nanotube (MWCNTs) or a mixture of MWCNTs and graphene (GE) nanoparticles (70/30 wt/wt) in order to investigate on both the synergistic effect provided by the two conductive nanostructured carbonaceous fillers and the correlation between formulation, morphology, and final properties of SLS printed porous structures. In detail, porous structures with a porosity ranging from 20% to 60% were designed using Diamond (D) and Gyroid (G) unit cells. Results showed that the carbonaceous fillers improve the thermal stability of the elastomeric matrix. Furthermore, the TPU/1 wt.% MWCNTs-GE-based porous structures exhibit excellent electrical conductivity and mechanical strength. In particular, all porous structures exhibit a robust negative piezoresistive behavior, as demonstrated from the gauge factor (GF) values that reach values of about −13 at 8% strain. Furthermore, the G20 porous structures (20% of porosity) exhibit microwave absorption coefficients ranging from 0.70 to 0.91 in the 12–18 GHz region and close to 1 at THz frequencies (300 GHz–1 THz). Results show that the simultaneous presence of MWCNTs and GE brings a significant enhancement of specific functional properties of the porous structures, which are proposed as potential actuators with relevant electro-magnetic interference (EMI) shielding properties.

Design of Three-Dimensional, Triply Periodic Unit Cell Scaffold Structures for Additive Manufacturing

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Mazher Iqbal Mohammed ◽  
Ian Gibson
Keyword(s):  
Additive Manufacturing ◽  
Periodic Structures ◽  
Three Dimensional ◽  
Unit Cell ◽  
Final Size ◽  
Fused Filament Fabrication ◽  
Cell Structures ◽  
Triply Periodic ◽  
Unit Cells ◽  
Scaffold Structure

Highly organized, porous architectures leverage the true potential of additive manufacturing (AM) as they can simply not be manufactured by any other means. However, their mainstream usage is being hindered by the traditional methodologies of design which are heavily mathematically orientated and do not allow ease of controlling geometrical attributes. In this study, we aim to address these limitations through a more design-driven approach and demonstrate how complex mathematical surfaces, such as triply periodic structures, can be used to generate unit cells and be applied to design scaffold structures in both regular and irregular volumes in addition to hybrid formats. We examine the conversion of several triply periodic mathematical surfaces into unit cell structures and use these to design scaffolds, which are subsequently manufactured using fused filament fabrication (FFF) additive manufacturing. We present techniques to convert these functions from a two-dimensional surface to three-dimensional (3D) unit cell, fine tune the porosity and surface area, and examine the nuances behind conversion into a scaffold structure suitable for 3D printing. It was found that there are constraints in the final size of unit cell that can be suitably translated through a wider structure while still allowing for repeatable printing, which ultimately restricts the attainable porosities and smallest printed feature size. We found this limit to be approximately three times the stated precision of the 3D printer used this study. Ultimately, this work provides guidance to designers/engineers creating porous structures, and findings could be useful in applications such as tissue engineering and product light-weighting.

scholarly journals Advanced Trans-Tibial Socket Fabrication Using Selective Laser Sintering

2007 ◽  
Vol 31 (1) ◽  
pp. 88-100 ◽  
Author(s):  
Bill Rogers ◽  
Gordon W. Bosker ◽  
Richard H. Crawford ◽  
Mario C. Faustini ◽  
Richard R. Neptune ◽  
...  
Keyword(s):  
Solid Freeform Fabrication ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Structural Features ◽  
Laser Sintering ◽  
Health Science ◽  
Science Center ◽  
University Of Texas ◽  
Three Dimensional Objects ◽  
Prosthetic Socket

There have been a variety of efforts demonstrating the use of solid freeform fabrication (SFF) for prosthetic socket fabrication though there has been little effort in leveraging the strengths of the technology. SFF encompasses a class of technologies that can create three dimensional objects directly from a geometric database without specific tooling or human intervention. A real strength of SFF is that cost of fabrication is related to the volume of the part, not the part's complexity. For prosthetic socket fabrication this means that a sophisticated socket can be fabricated at essentially the same cost as a simple socket. Adding new features to a socket design becomes a function of software. The work at The University of Texas Health Science Center at San Antonio (UTHSCSA) and University of Texas at Austin (UTA) has concentrated on developing advanced sockets that incorporate structural features to increase comfort as well as built in fixtures to accommodate industry standard hardware. Selective laser sintering (SLS) was chosen as the SFF technology to use for socket fabrication as it was capable of fabricating sockets using materials appropriate for prosthetics. This paper details the development of SLS prosthetic socket fabrication techniques at UTHSCSA/UTA over a six-year period.

Control-Oriented Modeling and Repetitive Control in In-Layer and Cross-Layer Thermal Interactions in Selective Laser Sintering

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Dan Wang ◽  
Tianyu Jiang ◽  
Xu Chen
Keyword(s):  
High Performance ◽  
Selective Laser Sintering ◽  
Repetitive Control ◽  
Three Dimensional ◽  
Process Variations ◽  
Laser Sintering ◽  
Laser Source ◽  
Cross Layer ◽  
Modeling And Control ◽  
Melt Pool

Abstract Although laser-based additive manufacturing (AM) has enabled unprecedented fabrication of complex parts directly from digital models, broader adoption of the technology remains challenged by insufficient reliability and in-process variations. In pursuit of assuring quality in the selective laser sintering (SLS) AM, this paper builds a modeling and control framework of the key thermodynamic interactions between the laser source and the materials to be processed. First, we develop a three-dimensional finite element simulation to understand the important features of the melt pool evolution for designing sensing and feedback algorithms. We explore how the temperature field is affected by hatch spacing and thermal properties that are temperature-dependent. Based on high-performance computer simulation and experimentation, we then validate the existence and effect of periodic disturbances induced by the repetitive in- and cross-layer thermomechanical interactions. From there, we identify the system model from the laser power to the melt pool width and build a repetitive control algorithm to greatly attenuate variations of the melt pool geometry.

Dimensional error of selective laser sintering, three-dimensional printing and PolyJet™ models in the reproduction of mandibular anatomy

2009 ◽  
Vol 37 (3) ◽  
pp. 167-173 ◽  
Author(s):  
Danilo Ibrahim ◽  
Tiago Leonardo Broilo ◽  
Claiton Heitz ◽  
Marília Gerhardt de Oliveira ◽  
Helena Willhelm de Oliveira ◽  
...  
Keyword(s):  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Dimensional Error ◽  
Three Dimensional Printing ◽  
Dimensional Printing

Three-Dimensional Modeling of Selective Laser Sintering of Two-Component Metal Powder Layers

2005 ◽  
Vol 128 (1) ◽  
pp. 299-306 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Metal Powder ◽  
Continuous Wave ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Scanning Velocity ◽  
Three Dimensional Modeling

Laser sintering of a metal powder mixture that contains two kinds of metal powders with significantly different melting points under a moving Gaussian laser beam is investigated numerically. The continuous-wave laser-induced melting accompanied by shrinkage and resolidification of the metal powder layer are modeled using a temperature-transforming model. The liquid flow of the melted low-melting-point metal driven by capillary and gravity forces is also included in the physical model. The numerical results are validated by experimental results, and a detailed parametric study is performed. The effects of the moving heat source intensity, the scanning velocity, and the thickness of the powder layer on the sintering depth, the configuration of the heat affected zone, and the temperature distribution are discussed.

Three dimensional printing of carbon/carbon composites by selective laser sintering

Carbon ◽  
2016 ◽  
Vol 96 ◽  
pp. 603-607 ◽  
Author(s):  
Xu Yi ◽  
Zhou-Jian Tan ◽  
Wan-Jing Yu ◽  
Jun Li ◽  
Bing-Ju Li ◽  
...  
Keyword(s):  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Carbon Composites ◽  
Three Dimensional Printing ◽  
Dimensional Printing

scholarly journals Selective Laser Sintering – Binding Mechanism And Assistance In Medical Applications

2015 ◽  
Vol 15 (3) ◽  
pp. 5-16
Author(s):  
Ż. A. Mierzejewska ◽  
W. Markowicz
Keyword(s):  
Biomedical Engineering ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Training Models ◽  
Three Dimensional Objects ◽  
Tissue Replacement ◽  
Dental Implantation ◽  
Custom Made ◽  
Complicated Geometry

Abstract Rapid prototyping technology (RP), based on designing and computer aided manufacturing, is widely used in traditional branches of industry. Due to its ability to accurately and precisely manufacture designed elements of various dimensions and complicated geometry, this technology is more and more frequently applied in the field of biomedical engineering. Selective laser sintering (SLS) is a universal RP technique, utilizing a laser beam to sinter powdered materials and create three-dimensional objects. Data for producing parts for tissue replacement come from medical imaging capabilities and digital presentation of test results. This paper presents the following: general classification of RP methods, the concept and methodology of performing laser sintering, sintering mechanisms, and the application of elements manufactured using this technology in biomedical engineering, particularly for the production of scaffolds used in tissue cultures, skeletal and dental prostheses in dental implantation, manufacturing of custom-made implants that are individually adjusted to the patient, and for production of training models on which a team of surgeons can train a surgical technique.

scholarly journals Selective Laser Melting of PA 2200 for Hip Implant Applications: Finite Element Analysis, Process Optimization, and Morphological and Mechanical Characterization

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4240
Author(s):  
Răzvan Păcurar ◽  
Petru Berce ◽  
Anna Petrilak ◽  
Ovidiu Nemeş ◽  
Cristina Ştefana Miron Borzan ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Surface Roughness ◽  
Finite Element ◽  
Selective Laser Sintering ◽  
Processing Parameters ◽  
Laser Sintering ◽  
Compression Tests ◽  
Element Analysis ◽  
Polyamide 12 ◽  
Research Activities

Polyamide 12 (PA 22000) is a well-known material and one of the most biocompatible materials tested and used to manufacture customized medical implants by selective laser sintering technology. To optimize the implants, several research activities were considered, starting with the design and manufacture of test samples made of PA 2200 by selective laser sintering (SLS) technology, with different processing parameters and part orientations. The obtained samples were subjected to compression tests and later to SEM analyses of the fractured zones, in which we determined the microstructural properties of the analyzed samples. Finally, an evaluation of the surface roughness of the material and the possibility of improving the surface roughness of the realized parts using finite element analysis to determine the optimum contact pressure between the component made of PA 2200 by SLS and the component made of TiAl6V4 by SLM was performed.

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