Additive Manufacturing-Based Adaptive Dynamic Parameter Characterization by Using Pressure-Fed Flexure Mechanisms

2019 ◽  
Author(s):  
ChaBum Lee ◽  
JaeMin Han ◽  
Gyu Ha Kim
Keyword(s):  
Additive Manufacturing ◽  
Dynamic Characteristics ◽  
Low Cost ◽  
Damping Ratio ◽  
Dynamic Parameter ◽  
Fluidic Channel ◽  
Cross Sectional ◽  
Channel Geometry ◽  
Dynamic Behaviors ◽  
Time Dynamic

Abstract This paper presents dynamic characteristics of pressure-fed flexure mechanisms with the additively manufactured internal fluidic channels. Additive manufacturing (AM) technology makes use of the mechanical design flexibility that can effectively control the material distribution in terms of stiffness and damping of the flexures. Five different fluidic channel geometry (circular, semicircular, inverse-semicircular, triangular, and inverse-triangular) with the same cross-sectional area was designed and fabricated inside of one-dimensional cantilever beam (10 × 30 × 100 mm3). Stiffness, damping ratio and natural frequency of each cantilever according to varying air pressure condition from 14.7 psi (atmospheric pressure) to 75 psi were characterized, and at the same time dynamic behaviors of each cantilever were identified by using dynamic signal analyzer. In addition, dynamic characteristics of water-filled flexure mechanism were compared to those of air-filled cases. As a result, the internal channel geometry and filled-in media in the channel have significant influences to determine dynamic characteristics of flexure mechanisms. Such pressure-fed mechanisms can be considered in the first stage of AM flexure design and fabrication processes to adaptively control dynamic behaviors in an easy, convenient and low-cost manner.

scholarly journals A Comprehensive 3D-Molded Bone Flap Protocol for Patient-Specific Cranioplasty

2021 ◽  
Author(s):  
Raphael Bertani ◽  
Caio Moreno Perret Novo ◽  
Pedro Henrique Freitas ◽  
Amanda Amorin Nunes ◽  
Thiago Nunes Palhares ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Low Cost ◽  
Selective Laser Sintering ◽  
Operating Time ◽  
Ct Scanning ◽  
Patient Specific ◽  
Manufacturing Cost ◽  
Post Processing ◽  
Cross Sectional ◽  
Cranial Defect

Abstract We present a detailed step-by-step approach for the low-cost production and surgical implantation of cranial prostheses, aimed at restoring aesthetics, cerebral protection, and facilitating neurological rehabilitation. This protocol uses combined scan computed tomography (CT) cross-sectional images, in DICOM format, along with a 3D printing (additive manufacturing) setup. The in-house developed software InVesalius®️ is an open-source tool for medical imaging manipulation. The protocol describes image acquisition (CT scanning) procedures, and image post-processing procedures such as image segmentation, surface/volume rendering, mesh generation of a 3D digital model of the cranial defect and the desired prostheses, and their preparation for use in 3D printers. Furthermore, the protocol describes a detailed powder bed fusion additive manufacturing process, known as Selective Laser Sintering (SLS), using Polyamide (PA12) as feedstock to produce a 3-piece customized printed set per patient. Each set consists of a “cranial defect printout” and a “testing prosthesis” to assemble parts for precision testing, and a cranial “prostheses mold” in 2 parts to allow for the intraoperative modeling of the final implant cast using the medical grade Poly(methyl methacrylate) (PMMA) in a time span of a few min. The entire 3D processing time, including modelling, design, production, post-processing and qualification, takes approximately 42 h. Modeling the PMMA flap with a critical thickness of 4 mm by means of Finite Element Method (FEM) assures mechanical and impact properties to be slightly weaker than the bone tissue around it, a safety design to prevent fracturing the skull after a possible subsequent episode of head injury. On a parallel track, the Protocol seeks to provide guidance in the context of equipment, manufacturing cost and troubleshooting. Customized 3D PMMA prostheses offers a reduced operating time, good biocompatibility, and great functional and aesthetic outcomes. Additionally, it offers greater than 15-fold cost advantage over the usage of other materials, including metallic parts produced by additive manufacturing.

Influence of Specimen Layout on 17-4PH (AISI 630) Alloys Fabricated by Low-Cost Additive Manufacturing

2021 ◽  
Author(s):  
Chanun Suwanpreecha ◽  
Phanuphak Seensattayawong ◽  
Vorawat Vadhanakovint ◽  
Anchalee Manonukul
Keyword(s):  
Additive Manufacturing ◽  
Low Cost

Association between the FINDRISC score and the risk of metabolic syndrome and hepatic steatosis

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Godoi Bernardes Da Silva ◽  
R Dias Santos ◽  
M Sommer Bittencourt ◽  
J.A.M Carvalho ◽  
M Franken ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Hepatic Steatosis ◽  
Longitudinal Analysis ◽  
Metabolic Diseases ◽  
Low Cost ◽  
Cross Sectional ◽  
Predictive Values ◽  
Cross Sectional Analysis ◽  
The Cross ◽  
Sectional Analysis

Abstract Introduction The Finnish Diabetes Risk Score (FINDRISC) was developed in Europe to predict type 2 diabetes mellitus (T2DM) risk without need of laboratory tests. Small cross-sectional studies analyzed the association between RF with metabolic syndrome (MS) or hepatic steatosis (HS). Our objective was to test the association of FINDRISC with MS or HS, in a transversal and longitudinal way. Methods In 41,668 individuals (age 41.9±9.7 years; 30.8% women) who underwent health evaluation between 2008 and 2016 in a single centre in Brazil, we tested the transversal association between FINDRISC and MS or HS, in multivariate models. The same analyzes were performed longitudinally in non-diabetic subgroups, followed for 5±3 years, to test the predictive value of FINDRISC and the incidental risk of MS (n=10,075 individuals) or HS (n=7,097 individuals), using logistic regression. Models were adjusted for confounders such as sex, use of medications for dyslipidemia, smoking, and baseline plasma levels of glucose, creatinine and lipids. A receiver operating characteristic (ROC) curve was used to evaluate the discriminative and predictive values of FINDRISC for MS and HS. Results In the cross-sectional analysis, 2,252 (5%) individuals had MS and 14,176 (34%) HS. In the longitudinal analysis, there were 302 cases of incidental MS (2%) and 1,096 cases of HS (15%). FINDRISC was independently associated with MS and HS in the cross-sectional analysis (respectively, OR 1.27, 95% CI: 1.25–1.28, P<0.001; and OR 1.21, 95% CI: 1.20–1.22, P<0.001, per FINDRISC unit) and in longitudinal analysis (respectively, OR of 1.18, 95% CI: 1.15–1.21, P<0.001; and OR of 1.10, 95% CI: 1.08–1.11, P<0.001, per FINDRISC unit). In comparison with individuals with low FINDRISC, those with moderate, high and very high values showed significant and proportional increases of the 12 to 77 fold in the chance of current SM (P<0.001) and 3 to 10 fold in the chance of HS (P<0.001). During follow-up, these increases were 3 to 10 fold in the chance of incidental MS (P<0.001) and 1 to 3 fold in the chance of HS (P<0.001). The AUC from cross-sectional analysis for MS and HS were respectively 0.82 (95% CI 0.81–0.83) and 0.76 (95% CI 0.75–0.76), and in longitudinal analysis 0.73 (95% CI 0.70–0.76) and 0.63 (95% CI 0.61–0.65), respectively. Conclusion FINDRISC was associated with the presence and onset of MS and HS, but it predicted better metabolic syndrome risk than hepatic steatosis. Therefore, this simple, practical and low-cost score can be useful for population screening and identification of subgroups of individuals at higher risk future metabolic diseases. Funding Acknowledgement Type of funding source: None

Printing of Low Cost Sensors by Additive Manufacturing

2021 ◽  
Author(s):  
Salman Ahmad ◽  
Muhammad Shakeel ◽  
Nadeem Iqbal ◽  
Mohsin Amin ◽  
Khalid Rahman
Keyword(s):  
Additive Manufacturing ◽  
Low Cost

scholarly journals Correlations between Coffee Consumption and Metabolic Phenotypes, Plasma Folate, and Vitamin B12: NHANES 2003 to 2006

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1348
Author(s):  
Pratibha V. Nerurkar ◽  
Krupa Gandhi ◽  
John J. Chen
Keyword(s):  
Vitamin B12 ◽  
Dietary Intervention ◽  
Low Cost ◽  
Coffee Consumption ◽  
Normal Weight ◽  
Dietary Factors ◽  
Cross Sectional ◽  
Metabolic Phenotypes ◽  
Plasma Folate ◽  
Prospective Longitudinal

Metabolic syndrome (MetS) is prevalent not only among the overweight and obese but also normal weight individuals, and the phenotype is referred to as a metabolically unhealthy phenotype (MUHP). Besides normal weight individuals, overweight/obese individuals are also protected from MetS, and the phenotype is known as a metabolically healthy phenotype (MHP). Epidemiological studies indicate that coffee and micronutrients such as plasma folate or vitamin B12 (vit. B12) are inversely associated with MetS. However, correlations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 remain unknown. Our objective was to investigate the correlation between coffee consumption, metabolic phenotypes, plasma folate, and vit. B12 as well as to understand associations between plasma folate, vit. B12, and metabolic phenotypes. Associations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 were assessed in a cross-sectional study of 2201 participants, 18 years or older, from 2003–2004 and 2005–2006 National Health and Nutrition Examination Surveys (NHANES). MUHP was classified as having > three metabolic abnormalities. Coffee consumption was not associated with metabolic phenotypes, but negatively correlated with several metabolic variables, including BMI (p < 0.001). Plasma folate was positively associated with MUHP (p < 0.004), while vit. B12 was inversely associated with MUHP (p < 0.035). Our results suggest the potential protective impact of coffee on individual components of MetS and indicate a positive correlation between coffee consumption and MUHP among overweight individuals. Identifying possible dietary factors may provide practical and low-cost dietary intervention targets, specifically for early intervention. Larger and randomized intervention studies and prospective longitudinal studies are required to further evaluate these associations.

The Costs and Benefits of Shareholder Democracy: Gadflies and Low-Cost Activism

2020 ◽  
Author(s):  
Nickolay Gantchev ◽  
Mariassunta Giannetti
Keyword(s):  
Low Cost ◽  
Shareholder Value ◽  
Career Concerns ◽  
Costs And Benefits ◽  
Cross Sectional ◽  
Shareholder Proposals ◽  
Active Individual ◽  
Shareholder Democracy ◽  
To Receive

Abstract We show that there is cross-sectional variation in the quality of shareholder proposals. On average, proposals submitted by the most active individual sponsors are less likely to receive majority support, but they occasionally pass if shareholders mistakenly support them and may even be implemented due to directors’ career concerns. While gadfly proposals destroy shareholder value if they pass, shareholder proposals on average are value enhancing in firms with more informed shareholders. We conclude that more informed voting could increase the benefits associated with shareholder proposals.

scholarly journals Gold, Silver, and Electrum Electroless Plating on Additively Manufactured Laser Powder-Bed Fusion AlSi10Mg Parts: A Review

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Dana Ashkenazi ◽  
Alexandra Inberg ◽  
Yosi Shacham-Diamand ◽  
Adin Stern
Keyword(s):  
Additive Manufacturing ◽  
Low Cost ◽  
Ion Beam ◽  
Surface Finishing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Finishing Process ◽  
Gold Silver ◽  
3D Printed

Additive manufacturing (AM) revolutionary technologies open new opportunities and challenges. They allow low-cost manufacturing of parts with complex geometries and short time-to-market of products that can be exclusively customized. Additive manufactured parts often need post-printing surface modification. This study aims to review novel environmental-friendly surface finishing process of 3D-printed AlSi10Mg parts by electroless deposition of gold, silver, and gold–silver alloy (e.g., electrum) and to propose a full process methodology suitable for effective metallization. This deposition technique is simple and low cost method, allowing the metallization of both conductive and insulating materials. The AlSi10Mg parts were produced by the additive manufacturing laser powder bed fusion (AM-LPBF) process. Gold, silver, and their alloys were chosen as coatings due to their esthetic appearance, good corrosion resistance, and excellent electrical and thermal conductivity. The metals were deposited on 3D-printed disk-shaped specimens at 80 and 90 °C using a dedicated surface activation method where special functionalization of the printed AlSi10Mg was performed to assure a uniform catalytic surface yielding a good adhesion of the deposited metal to the substrate. Various methods were used to examine the coating quality, including light microscopy, optical profilometry, XRD, X-ray fluorescence, SEM–energy-dispersive spectroscopy (EDS), focused ion beam (FIB)-SEM, and XPS analyses. The results indicate that the developed coatings yield satisfactory quality, and the suggested surface finishing process can be used for many AM products and applications.

Cross-sectional microanalysis for tracking the effect of solvent on the morphological evaluation of PLA/AgNWs bionanocomposties

2021 ◽  
pp. 096739112110230
Author(s):  
Meltem Sezen ◽  
Busra Tugba Camic
Keyword(s):  
Focused Ion Beam ◽  
Silver Nanowires ◽  
Low Cost ◽  
Ion Beam ◽  
Lower Surface ◽  
Polymer Matrices ◽  
Elemental Distribution ◽  
Medical Sciences ◽  
Surface Area Ratio ◽  
Cross Sectional

The emphasis of biocompatible polymer applications in medical sciences and biotechnology has remarkably increased. Developing new low-cost, low-toxicity and lightweight composite forms of biopolymers has become even more attractive since the addition of new species into polymer matrices assist to improve biomedical activities of such materials to a higher extend. Developments in nanoscience and nanotechnology recently contribute to controlled fabrication and ultraprecise diagnosis of such materials. This study concerns the observation of solution processing effects in the fabrication of porous PLA/AGNWs bionanocomposite coatings using electron and ion processing based serial cross-sectioning and high-resolution imaging. The nanostructuring and characterization were both performed in a focused ion-beam-scanning electron microscope (FIB-SEM) platform. HR-SEM imaging was conducted on-site to track solvent based morphological property alterations of PLA and PLA/AgNWs structures. Simultaneous SEM-EDS analyses revealed the elemental distribution and the chemical composition along the cross-sectioned regions of the samples. Accordingly, it was observed that, in case of acetone dissolved materials, both pristine PLA and PLA/AgNWs samples sustained their foamy structure. When chloroform was used as the solvent, the porosity of the polymer matrices was less and the resulting structure was found to be denser than samples dissolved in acetone with a lower surface area ratio inside the material. This can be attributed to the rapid volatilization of acetone compared to chloroform, and hence the formation of interconnected pore network. For both nanocomposite biopolymers dissolved in acetone and chloroform, silver nanowires were homogeneously distributed throughout PLA matrices.

scholarly journals Development of an Additive Manufacturing System for the Deposition of Thermoplastics Impregnated with Carbon Fibers

2019 ◽  
Vol 3 (2) ◽  
pp. 35 ◽  
Author(s):  
Miguel Reis Silva ◽  
António M. Pereira ◽  
Nuno Alves ◽  
Gonçalo Mateus ◽  
Artur Mateus ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Carbon Fibers ◽  
Low Cost ◽  
Deposition Process ◽  
Processing Parameters ◽  
Yarn Diameter ◽  
Thermoplastic Matrix ◽  
Anisotropic Mechanical Properties ◽  
Long Carbon Fiber

This work presents an innovative system that allows the oriented deposition of continuous fibers or long fibers, pre-impregnated or not, in a thermoplastic matrix. This system is used in an integrated way with the filamentary fusion additive manufacturing technology and allows a localized and oriented reinforcement of polymer components for advanced engineering applications at a low cost. To demonstrate the capabilities of the developed system, composite components of thermoplastic matrix (polyamide) reinforced with pre-impregnated long carbon fiber (carbon + polyamide), 1 K and 3 K, were processed and their tensile and flexural strength evaluated. It was demonstrated that the tensile strength value depends on the density of carbon fibers present in the composite, and that with the passage of 2 to 4 layers of fibers, an increase in breaking strength was obtained of about 366% and 325% for the 3 K and 1 K yarns, respectively. The increase of the fiber yarn diameter leads to higher values of tensile strength of the composite. The obtained standard deviation reveals that the deposition process gives rise to components with anisotropic mechanical properties and the need to optimize the processing parameters, especially those that lead to an increase in adhesion between deposited layers.

scholarly journals Multiscale additive manufacturing of polymers using 3D photo-printable self-assembling ionic liquid monomers

2019 ◽  
Vol 4 (3) ◽  
pp. 580-585 ◽  
Author(s):  
Bineh G. Ndefru ◽  
Bryan S. Ringstrand ◽  
Sokhna I.-Y. Diouf ◽  
Sönke Seifert ◽  
Juan H. Leal ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Additive Manufacturing ◽  
Self Assembly ◽  
Low Cost ◽  
Low Resolution ◽  
Top Down ◽  
Bottom Up ◽  
Cost Approach ◽  
Self Assembling ◽  
Nanoscale Features

Combining bottom-up self-assembly with top-down 3D photoprinting affords a low cost approach for the introduction of nanoscale features into a build with low resolution features.

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