Characterization of sintered hydroxyapatite samples produced by 3D printing

2014 ◽  
Vol 20 (5) ◽  
pp. 413-421 ◽  
Author(s):  
I. Pires ◽  
B. Gouveia ◽  
J. Rodrigues ◽  
R. Fonte
Keyword(s):  
Phase Stability ◽  
Mechanical Stability ◽  
Sintering Temperature ◽  
Calcium Phosphates ◽  
Complex Structure ◽  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Compression Tests ◽  
Powder Morphology ◽  
Content Type

Purpose – The purpose of this study is to characterize sintered hydroxyapatite (HA) samples produced by three-dimensional printing (3DP). This study is part of a project concerned with the fabrication of calcium phosphates implants by 3DP. However, before considering a more complex structure, like scaffolds or implants, a thorough knowledge of the role played by the sintering temperature on physical and mechanical the properties of porous HA is necessary. Design/methodology/approach – The characteristics of sintered HA samples have been analyzed by means of x-ray diffraction, scanning electron microscope (SEM) and uniaxial compression tests. The 3DP parameters used to produce the HA samples were those who led to higher accuracy and mechanical stability. Findings – Sintering temperature and powder morphology are critical factors influencing densification behavior, porosity, phase stability, mechanical strength and tangent modulus of the HA samples produced by 3DP. This study allowed us to conclude about the 3DP parameters to be used to produce porous HA specimens with the required integrity and dimensional accuracy, and the optimal post-processing sintering temperature which led to the best results in terms of porosity, microstructure, phase stability of HA and mechanical properties. Originality/value – This paper provides a method to evaluate the manufacturability of calcium phosphate models produced by 3DP.

Synthesis and properties of modified PBT for FDM

2017 ◽  
Vol 23 (4) ◽  
pp. 804-810 ◽  
Author(s):  
Shiqing Cao ◽  
Dandan Yu ◽  
Weilan Xue ◽  
Zuoxiang Zeng ◽  
Wanyu Zhu
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Fused Deposition Modeling ◽  
Complex Structure ◽  
Three Dimensional ◽  
Sebacic Acid ◽  
Wire Drawing ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling

Purpose The purpose of this paper is to prepare a new modified polybutylene terephalate (MPBT) for fused deposition modeling (FDM) to increase the variety of materials compatible with printing. And the printing materials can be used to print components with a complex structure and functional mechanical parts. Design/methodology/approach The MPBT, poly(butylene terephalate-co-isophthalate-co-sebacate) (PBTIS), was prepared for FDM by direct esterification and subsequent polycondensation using terephthalic acid (PTA), isophthalic acid (PIA), sebacic acid (SA) and 1,4-butanediol (BDO). The effects of the content of PIA (20-40 mol%) on the mechanical properties of PBTIS were investigated when the mole per cent of SA (αSA) is zero. The effects of αSA (0-7mol%) on the thermal, rheological and mechanical properties of PBTIS were investigated at nPTA/nPIA = 7/3. A desktop wire drawing and extruding machine was used to fabricate the filaments, whose printability and anisotropy were tested by three-dimensional (3D) printing experiments. Findings A candidate content of PIA introducing into PBT was obtained to be about 30 per cent, and the Izod notched impact strength of PBTIS increased with the increase of αSA. The results showed that the PBTIS (nPTA/nPIA = 7/3, αSA = 3-5mol%) is suitable for FDM. Originality/value New printing materials with good Izod notched impact strength were obtained by introducing PIA and SA (nPTA/nPIA = 7/3, αSA = 3-5 mol%) into PBT and their anisotropy are better than that of ABS.

Investigation of dimensional accuracy of metal droplet deposition under repulsion using a lattice Boltzmann approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yanlin Ren ◽  
Zhaomiao Liu ◽  
Yan Pang ◽  
Xiang Wang ◽  
Shanshan Gao
Keyword(s):  
Lattice Boltzmann ◽  
Moving Boundary ◽  
Three Dimensional ◽  
Metal Droplet ◽  
Dimensional Accuracy ◽  
Longitudinal Section ◽  
Collision Term ◽  
Droplet Deposition ◽  
Content Type ◽  
Deposition Distance

Purpose This paper aims to investigate the influence of droplet infiltration and sliding on the deposition size and make a uniform deposition by controlling the interaction between droplets, using the three-dimensional lattice Boltzmann method (LBM) based on the actual working condition. Design/methodology/approach D3Q19 Shan-Chen LB approach is developed and optimized based on the metal droplet deposition. The Carnahan-Starling equation of state and transition layers are introduced to maintain the greater stability and low pseudo velocities. In addition, an additional collision term is adopted to implement immersed moving boundary scheme to deal with no-slip boundaries on the front of the phase change. Findings The numerical results show that the new¬ incoming droplet wet and slide off the solidified surface and the rejection between droplets are the reasons for the deviation of the actual deposition length. The total length of the longitudinal section negatively correlates with the deposition distance. To improve the dimensional accuracy, the deposition distance and repulsion rate need to be guaranteed. The optimal deposition distance is found to have a negative linear correlation with wettability. Originality/value The numerical model developed in this paper will help predict the continuous metal droplet deposition and provide guidance for the selection of deposition distance.

scholarly journals The use of rapid prototyping in the joining of fractured historical silver object

2018 ◽  
Vol 24 (3) ◽  
pp. 532-538 ◽  
Author(s):  
Maria Luiza Seixas ◽  
Paulo Santos Assis ◽  
João Cura D’Ars Figueiredo ◽  
Maria Aparecida Pinto ◽  
Daniella Gualberto Caldeira Paula
Keyword(s):  
Rapid Prototyping ◽  
Design Methodology ◽  
Mechanical Stability ◽  
Dimensional Accuracy ◽  
3D Modelling ◽  
Content Type ◽  
Minimal Impact ◽  
Speed Up ◽  
Elemental Chemical Analysis ◽  
Original Metal

Purpose This paper aims to present a proposal for the restoration of a silver crown by means of fitting pieces produced by the process of 3D modelling and rapid prototyping. It also analyses the benefits of this procedure in restoration of objects weakened by corrosive processes. Design/methodology/approach Elemental chemical analysis was carried out in the alloy used in the manufacture of the crown and the constructive and corrosive processes present were studied. Three fitting pieces were modelled and prototyped in wax casting by the stereolithography apparatus system aiming to restore the part and protect the original metal against impacts and external tensions which could speed up some deterioration processes. Findings The procedure presented in this paper has shown that formal and dimensional accuracy, only achieved by means of 3D technologies, made the restoration and mechanical stability of the crown possible without the use of adhesives or welding. Originality/value The proposed procedure is a new restoration alternative which causes minimal impact to the object and abides by the main standards for modern conservation. It is made with metal which is compatible with the original piece, retractable and easily identifiable.

Experimental study on the accuracy and surface quality of printed versus machined holes in PEI Ultem 9085 FDM specimens

2021 ◽  
Vol 27 (11) ◽  
pp. 1-12
Author(s):  
Giovanni Gómez-Gras ◽  
Marco A. Pérez ◽  
Jorge Fábregas-Moreno ◽  
Guillermo Reyes-Pozo
Keyword(s):  
Surface Quality ◽  
Fused Deposition Modeling ◽  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Technological Parameters ◽  
Content Type ◽  
Fused Deposition ◽  
Comparison Of The Results ◽  
Through Hole

Purpose This paper aims to investigate the quality of printed surfaces and manufacturing tolerances by comparing the cylindrical cavities machined in parts obtained by fused deposition modeling (FDM) with the holes manufactured during the printing process itself. The comparison focuses on the results of roughness and tolerances, intending to obtain practical references when making assemblies. Design/methodology/approach The experimental approach focuses on the comparison of the results of roughness and tolerances of two manufacturing strategies: geometric volumes with a through-hole and the through-hole machined in volumes that were initially printed without the hole. Throughout the study, both alternates are explained to make appropriate recommendations. Findings The study shows the best combinations of technological parameters, both machining and three-dimensional printing, which have been decisive for obtaining successful results. These conclusive results allow enunciating recommendations for use in the industrial environment. Originality/value This paper fulfills an identified need to study the dimensional accuracy of the geometries obtained by additive manufacturing, as no experimental evidence has been found of studies that directly address the problem of the FDM-printed part with geometric and dimensional tolerances and desirable surface quality for assembly.

scholarly journals Luminescent Nanosensors for Ratiometric Monitoring of Three-Dimensional Oxygen Gradients in Laboratory and Clinical Pseudomonas aeruginosa Biofilms

2019 ◽  
Vol 85 (20) ◽  
Author(s):  
Megan P. Jewell ◽  
Anne A. Galyean ◽  
J. Kirk Harris ◽  
Edith T. Zemanick ◽  
Kevin J. Cash
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Temporal Variation ◽  
Complex Structure ◽  
Three Dimensional ◽  
Spatial And Temporal Variation ◽  
Content Type ◽  
Oxygen Penetration ◽  
Oxygen Gradients ◽  
Oxygen Sensitive

ABSTRACT Bacterial biofilms can form persistent infections on wounds and implanted medical devices and are associated with many chronic diseases, such as cystic fibrosis. These infections are medically difficult to treat, as biofilms are more resistant to antibiotic attack than their planktonic counterparts. An understanding of the spatial and temporal variation in the metabolism of biofilms is a critical component toward improved biofilm treatments. To this end, we developed oxygen-sensitive luminescent nanosensors to measure three-dimensional (3D) oxygen gradients, an application of which is demonstrated here with Pseudomonas aeruginosa biofilms. The method was applied here and improves on traditional one-dimensional (1D) methods of measuring oxygen profiles by investigating the spatial and temporal variation of oxygen concentration when biofilms are challenged with antibiotic attack. We observed an increased oxygenation of biofilms that was consistent with cell death from comparisons with antibiotic kill curves for PAO1. Due to the spatial and temporal nature of our approach, we also identified spatial and temporal inhomogeneities in the biofilm metabolism that are consistent with previous observations. Clinical strains of P. aeruginosa subjected to similar interrogation showed variations in resistance to colistin and tobramycin, which are two antibiotics commonly used to treat P. aeruginosa infections in cystic fibrosis patients. IMPORTANCE Biofilm infections are more difficult to treat than planktonic infections for a variety of reasons, such as decreased antibiotic penetration. Their complex structure makes biofilms challenging to study without disruption. To address this limitation, we developed and demonstrated oxygen-sensitive luminescent nanosensors that can be incorporated into biofilms for studying oxygen penetration, distribution, and antibiotic efficacy—demonstrated here with our sensors monitoring antibiotic impacts on metabolism in biofilms formed from clinical isolates. The significance of our research is in demonstrating not only a nondisruptive method for imaging and measuring oxygen in biofilms but also that this nanoparticle-based sensing platform can be modified to measure many different ions and small molecule analytes.

Digital description model of a three-dimensional arrangement structure of conductive fiber of electromagnetic shielding fabric

2017 ◽  
Vol 29 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Xiuchen Wang ◽  
Yaping Li ◽  
Ying Su ◽  
Zhen Pan ◽  
Zhe Liu
Keyword(s):  
Feature Extraction ◽  
Complex Structure ◽  
Three Dimensional ◽  
Electromagnetic Shielding ◽  
Electromagnetic Properties ◽  
Shielding Effectiveness ◽  
Content Type ◽  
Conductive Fiber ◽  
Feature Parameters ◽  
Conductive Fibers

Purpose The three-dimensional arrangement structure of the conductive fiber is an important factor of the shielding effectiveness of the electromagnetic shielding fabric (EMSF). However, until now, the three-dimensional arrangement structure has not been described because of the complex structure, which leads to many difficulties for the subsequent analysis of the electromagnetic characteristics. Therefore, the purpose of this paper is to propose a feature extraction method to describe the arrangement structure of the conductive fiber based on the three-dimensional calibration and image processing technology, providing a new idea for the above problem. Design/methodology/approach First, the three-dimensional positions of the conductive fibers in the EMSF are calibrated using the VHX-600 3D digital microscope and the MATLAB7.5 software. The arrangement characteristics of the conductive fibers are analyzed, and equivalent twist, cross-sectional content, and average angle of a single fiber are proposed to describe the arrangement characteristic of the conductive fiber. Then, a digital description model of the conductive fiber is constructed according to the feature parameters and its three-dimensional structures are reproduced using CATIA. Finally, the reliability of the model is verified by an FDTD example, and the significance and application of the model are given. Findings The proposed method can provide the feature extraction and description for the complex spatial three-dimensional arrangement structure of conductive fibers. The feature parameters can reflect different micro arrangement features of the conductive fiber. The proposed idea and method can provide a solid foundation for subsequent studies of the electromagnetic properties of the EMSF. Originality/value The study in this paper is of great significance and academic value. This paper provides a new three-dimensional calibration method and constructs multiple feature parameters to describe the complex three-dimensional arrangement structure, providing a new effective method to overcome the problem of the conductive fiber description. The proposed method provides an important basis for the shielding mechanism, transmission characteristics, electromagnetic calculation and product design, and woven technology of the EMSF.

Variation modeling for fuselage structures in large aircraft digital assembly

2015 ◽  
Vol 35 (2) ◽  
pp. 172-182 ◽  
Author(s):  
Liang Cheng ◽  
Qing Wang ◽  
Jiangxiong Li ◽  
Yinglin Ke
Keyword(s):  
Complex Structure ◽  
Dimensional Accuracy ◽  
Good Prediction ◽  
Assembly Process ◽  
Structure Model ◽  
Content Type ◽  
Aircraft Assembly ◽  
Beam Elements ◽  
Position Errors ◽  
Large Aircraft

Purpose – The aim of this paper is to present a new variation modeling method for fuselage structures in digital large aircraft assembly. The variation accumulated in a large aircraft assembly process will influence the dimensional accuracy and fatigue life of airframes. However, in digital large aircraft assembly, variation analysis and modeling are still unresolved issues. Design/methodology/approach – An elastic structure model based on beam elements is developed, which is an equivalent idealization of the actual complex structure. The stiffness matrix of the structure model is obtained by summing the stiffness matrices of the beam elements. For each typical stage of the aircraft digital assembly process, including positioning, coordinating, joining and releasing, variation models are built using the simplified structure model with respective loads and boundary conditions. Findings – Using position errors and manufacturing errors as inputs, the variations for every stage of the assembly process can be calculated using the proposed model. Practical implications – This method has been used in a large fuselage section assembly project, and the calculated results were shown to be a good prediction of variation in the actual assembly. Originality/value – Although certain assumptions have been imposed, the proposed method provides a better understanding of the assembly process and creates an analytical foundation for further work on variation control and tolerance optimization.

Benchmarking the complex geometric profiles, dimensional accuracy and surface analysis of printed parts

2019 ◽  
Vol 26 (2) ◽  
pp. 319-329 ◽  
Author(s):  
Paridhi Subbaian Kaliamoorthy ◽  
Rajkumar Subbiah ◽  
Joseph Bensingh ◽  
Abdul Kader ◽  
Sanjay Nayak
Keyword(s):  
Surface Roughness ◽  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Measuring System ◽  
Experimental Result ◽  
Complex Geometries ◽  
Thin Wall ◽  
Content Type ◽  
Metal Parts ◽  
Cooling Channels

Purpose Additive manufacturing has paved a way for geometrical freedom and mass customization of new and innovative products. However, it has a few limitations in printing complex geometries and sizes. The purpose of this paper is three-dimensional printing of metal parts using selective laser melting (SLM) has several intricacies. Design/methodology/approach To test the capabilities of SLM, the complex geometries of varying sizes, orientations, shapes such as square and cylindrical features, thin wall structures and holes were checked for dimensional accuracy and surface roughness. Findings The outcome of the study represents the capabilities of SLM and provide insight for solving the technological issues and processing constraint in the manufacture of metal parts from aluminum alloy. The analysis has proven that there is significant accuracy in dimension for large features in comparison with smaller one. The dimensional reproducibility was determined with the aid of an optical measuring system and the range of errors were calculated. These results show that the dimensional accuracy of the features in the printed part was within acceptable tolerance limits. This paper also investigated the significant contributing factors influencing printing of two and three-dimensional surface roughness based on the result of surface profilometer and it was observed that the surface was smoothened with the presence of overhangs and supports. Originality/value The ability of SLM to fabricate conformer cooling channels to support mould fabrication was tested. From the experimental result, it was observed that the quality of printing of conformal cooling channels depended on the diameter of channels with larger distortions in the channel having smaller diameter. The innovative aspect of the work was the study of build orientation combined with the investigated material.

scholarly journals Elucidation of the Molecular Basis for Arabinoxylan-Debranching Activity of a Thermostable Family GH62 α-l-Arabinofuranosidase from Streptomyces thermoviolaceus

2014 ◽  
Vol 80 (17) ◽  
pp. 5317-5329 ◽  
Author(s):  
Weijun Wang ◽  
Galina Mai-Gisondi ◽  
Peter J. Stogios ◽  
Amrit Kaur ◽  
Xiaohui Xu ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Complex Structure ◽  
Three Dimensional ◽  
Binding Pocket ◽  
Content Type ◽  
Wheat Arabinoxylan ◽  
Debranching Enzymes ◽  
The Family ◽  
Multiple Binding ◽  
Hydrolysis Of

ABSTRACTXylan-debranching enzymes facilitate the complete hydrolysis of xylan and can be used to alter xylan chemistry. Here, the family GH62 α-l-arabinofuranosidase fromStreptomyces thermoviolaceus(SthAbf62A) was shown to have a half-life of 60 min at 60°C and the ability to cleave α-1,3l-arabinofuranose (l-Araf) from singly substituted xylopyranosyl (Xylp) backbone residues in wheat arabinoxylan; low levels of activity on arabinan as well as 4-nitrophenyl α-l-arabinofuranoside were also detected. After selective removal of α-1,3l-Arafsubstituents from disubstituted Xylpresidues present in wheat arabinoxylan, SthAbf62A could also cleave the remaining α-1,2l-Arafsubstituents, confirming the ability of SthAbf62A to remove α-l-Arafresidues that are (1→2) and (1→3) linked to monosubstituted β-d-Xylpsugars. Three-dimensional structures of SthAbf62A and its complex with xylotetraose andl-arabinose confirmed a five-bladed β-propeller fold and revealed a molecular Velcro in blade V between the β1 and β21 strands, a disulfide bond between Cys27 and Cys297, and a calcium ion coordinated in the central channel of the fold. The enzyme-arabinose complex structure further revealed a narrow and seemingly rigidl-arabinose binding pocket situated at the center of one side of the β propeller, which stabilized the arabinofuranosyl substituent through several hydrogen-bonding and hydrophobic interactions. The predicted catalytic amino acids were oriented toward this binding pocket, and the catalytic essentiality of Asp53 and Glu213 was confirmed by site-specific mutagenesis. Complex structures with xylotetraose revealed a shallow cleft for xylan backbone binding that is open at both ends and comprises multiple binding subsites above and flanking thel-arabinose binding pocket.

Process capability study of three dimensional printing as casting solution for non ferrous alloys

2016 ◽  
Vol 22 (3) ◽  
pp. 474-486 ◽  
Author(s):  
Rajesh Kumar ◽  
Rupinder Singh ◽  
IPS Ahuja
Keyword(s):  
Research Work ◽  
Three Dimensional ◽  
Process Capability ◽  
Dimensional Accuracy ◽  
Ferrous Alloy ◽  
Content Type ◽  
Three Dimensional Printing ◽  
Casting Solution ◽  
Measuring Machine ◽  
Dimensional Printing

Purpose The purpose of this paper is to investigate the process capability of three-dimensional printing (3DP)-based casting solutions for non-ferrous alloy (NFA) components. Design/methodology/approach After selection and design of benchmark, prototypes for six different NFA materials were prepared by using 3DP (ZCast process)-based shell moulds. Coordinate measuring machine has been used for calculating the dimensional tolerances of the NFA components. Consistency with the tolerance grades of the castings has been checked as per IT grades. Findings The results of process capability investigation highlight that the 3DP process as a casting solution for NFA component lies in ±5sigma (s) limit, as regards to dimensional accuracy is concerned. Further, this process ensures rapid production of pre-series industrial prototypes for NFA. Final components prepared are also acceptable as per ISO standard UNI EN 20,286-I (1995). Originality/value This research work presents capability of the 3DP process supported with experimental data on basis of various process parameters for the tolerance grade of NFA castings. These statistics can help to enhance the application of 3DP-based NFA casting process in commercial foundry industry.

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