scholarly journals Photogrammetric analysis of additive manufactured metallic open cell porous structures

2018 ◽  
Vol 24 (8) ◽  
pp. 1380-1391 ◽  
Author(s):  
Samuel Evans ◽  
Eric Jones ◽  
Peter Fox ◽  
Chris Sutcliffe
Keyword(s):  
Pore Size ◽  
Low Cost ◽  
High Volume ◽  
Porous Structures ◽  
Micro Computed Tomography ◽  
Open Cell ◽  
Content Type ◽  
Material Thickness ◽  
Computed Tomography Scanning ◽  
Photogrammetric Method

PurposeThis paper aims to introduce a novel method for the analysis of open cell porous components fabricated by laser-based powder bed metal additive manufacturing (AM) for the purpose of quality control. This method uses photogrammetric analysis, the extraction of geometric information from an image through the use of algorithms. By applying this technique to porous AM components, a rapid, low-cost inspection of geometric properties such as material thickness and pore size is achieved. Such measurements take on greater importance, as the production of porous additive manufactured orthopaedic devices increases in number, causing other, slower and more expensive methods of analysis to become impractical.Design/methodology/approachHere the development of the photogrammetric method is discussed and compared to standard techniques including scanning electron microscopy, micro computed tomography scanning and the recently developed focus variation (FV) imaging. The system is also validated against test graticules and simple wire geometries of known size, prior to the more complex orthopaedic structures.FindingsThe photogrammetric method shows an ability to analyse the variability in build fidelity of AM porous structures for use in inspection purposes to compare component properties. While measured values for material thickness and pore size differed from those of other techniques, the new photogrammetric technique demonstrated a low deviation when repeating measurements, and was able to analyse components at a much faster rate and lower cost than the competing systems, with less requirement for specific expertise or training.Originality/valueThe advantages demonstrated by the image-based technique described indicate the system to be suitable for implementation as a means of in-line process control for quality and inspection applications, particularly for high-volume production where existing methods would be impractical.

Analysis of variability in additive manufactured open cell porous structures

2017 ◽  
Vol 231 (6) ◽  
pp. 534-546
Author(s):  
Sam Evans ◽  
Eric Jones ◽  
Pete Fox ◽  
Chris Sutcliffe
Keyword(s):  
Porous Material ◽  
Pore Size ◽  
Porous Structures ◽  
Micro Computed Tomography ◽  
Microscopy Imaging ◽  
Geometric Properties ◽  
Open Cell ◽  
Material Thickness ◽  
Cell Structures ◽  
The Mean

In this article, a novel method of analysing build consistency of additively manufactured open cell porous structures is presented. Conventionally, methods such as micro computed tomography or scanning electron microscopy imaging have been applied to the measurement of geometric properties of porous material; however, high costs and low speeds make them unsuitable for analysing high volumes of components. Recent advances in the image-based analysis of open cell structures have opened up the possibility of qualifying variation in manufacturing of porous material. Here, a photogrammetric method of measurement, employing image analysis to extract values for geometric properties, is used to investigate the variation between identically designed porous samples measuring changes in material thickness and pore size, both intra- and inter-build. Following the measurement of 125 samples, intra-build material thickness showed variation of ±12%, and pore size ±4% of the mean measured values across five builds. Inter-build material thickness and pore size showed mean ranges higher than those of intra-build, ±16% and ±6% of the mean material thickness and pore size, respectively. Acquired measurements created baseline variation values and demonstrated techniques suitable for tracking build deviation and inspecting additively manufactured porous structures to indicate unwanted process fluctuations.

Multiscale imaging of the rat brain using an integrated diceCT and histology workflow

2021 ◽  
Author(s):  
Paul M. Gignac ◽  
Haley D. O’Brien ◽  
Jimena Sanchez ◽  
Dolores Vazquez Sanroman
Keyword(s):  
Computed Tomography ◽  
Low Cost ◽  
Three Dimensional ◽  
Adolescent Male ◽  
Cresyl Violet ◽  
Sprague Dawley ◽  
Biomedical Sciences ◽  
Micro Computed Tomography ◽  
Computed Tomography Scanning ◽  
Neural Tissues

Abstract Advancements in tissue visualization techniques have spurred significant gains in the biomedical sciences by enabling researchers to integrate their datasets across anatomical scales. Of particular import are techniques that enable the interpolation of multiple hierarchical scales in samples taken from the same individuals. This study demonstrates that two-dimensional histology techniques can be employed on neural tissues following three-dimensional diffusible iodine-based contrast-enhanced computed tomography (diceCT) without causing tissue degradation. This represents the first step toward a multiscale pipeline for brain visualization. We studied brains from adolescent male Sprague-Dawley rats, comparing experimental (diceCT-stained then de-stained) to control (without diceCT) brains to evaluate neural tissues for immunolabeling integrity, compare somata sizes, and distinguish neurons from glial cells within the telencephalon and diencephalon. We hypothesized that if experimental and control samples do not differ significantly in quantitative metrics, brain tissues are robust to the chemical, temperature, and radiation environments required for these multiple, successive imaging protocols. Visualizations for experimental brains were first captured via micro-computed tomography scanning of isolated, iodine-infused specimens. Samples were then cleared of iodine, serially sectioned, and prepared again using immunofluorescent, fluorescent, and cresyl violet labeling, followed by imaging with confocal and light microscopy, respectively. Our results show that many neural targets are resilient to diceCT imaging and compatible with downstream histological staining as part of a low-cost, multiscale brain imaging pipeline.

Fabrication of three dimensional open porous regular structure of PA-2200 for enhanced strength of scaffold using selective laser sintering

2016 ◽  
Vol 22 (4) ◽  
pp. 752-765 ◽  
Author(s):  
Jatender Pal Singh ◽  
Pulak M. Pandey ◽  
Anita Kamra Verma
Keyword(s):  
Porous Structure ◽  
Pore Size ◽  
Process Parameters ◽  
Cell Structure ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Open Cell ◽  
Content Type ◽  
Open Porous Structure

Purpose Scaffolds are essentially required to have open porous structure for facilitating bone to grow. They are generally placed on those bone defective/fractured sites which are more prone to compressive loading. Open porous structure lacks in strength in comparison to solid. Selective laser sintering (SLS) process is prominently used for fabrication of polymer/composite scaffolds. So, this paper aims to study for fabrication of three-dimensional open porous scaffolds with enhanced strength, process parameters of SLS of a biocompatible material are required to be optimized. Design/methodology/approach Regular open porous structures with suitable pore size as per computer-aided design models were fabricated using SLS. Polyamide (PA-2200) was used to fabricate the specimen/scaffold. To optimize the strength of the designed structure, response surface methodology was used to design the experiments. Specimens as per ASTM D695 were fabricated using SLS and compressive testing was carried out. Analysis of variance was done for estimating contribution of individual process parameters. Optimized process parameters were obtained using a trust region algorithm and correlated with experimental results. Accuracy of the fabricated specimen/scaffold was also assessed in terms of IT grades. In vitro cell culture on the fabricated structures confirmed the biocompatibility of polyamide (PA-2200). Findings Optimized process parameters for open cell process structures were obtained and confirmed experimentally. Laser power, hatch spacing and layer thickness have contributed more in the porous part’s strength than scan speed. The accuracy of the order of IT16 has been found for all functional dimensions. Cell growth and proliferation confirmed biocompatibility of polyamide (PA-2200) for scaffold applications. Originality/value This paper demonstrates the biocompatibility of PA-2200 for scaffold applications. The optimized process parameters of SLS process for open cell structure having pore size 1.2 × 1.2 mm2 with strut diameter of 1 mm have been obtained. The accuracy of the order of IT16 was obtained at the optimized process factors.

Three-dimensional model of an ancient Egyptian falcon mummy skeleton

2015 ◽  
Vol 21 (4) ◽  
pp. 368-372 ◽  
Author(s):  
Anton Du Plessis ◽  
Ruhan Slabbert ◽  
Liani Colette Swanepoel ◽  
Johan Els ◽  
Gerrie J Booysen ◽  
...  
Keyword(s):  
Computed Tomography ◽  
3D Printing ◽  
Three Dimensional ◽  
Micro Computed Tomography ◽  
Three Dimensional Model ◽  
Content Type ◽  
3D Print ◽  
Ancient Egyptian ◽  
Computed Tomography Scanning ◽  
Tomography Scanning

Purpose – The purpose of this paper is to present the first detailed three-dimensional (3D) print from micro-computed tomography data of the skeleton of an ancient Egyptian falcon mummy. Design/methodology/approach – Radiographic analysis of an ancient Egyptian falcon mummy housed at Iziko Museums of South Africa was performed using non-destructive x-ray micro-computed tomography. A 1:1 physical replica of its skeleton was printed in a polymer material (polyamide) using 3D printing technology. Findings – The combination of high-resolution computed tomography scanning and rapid prototyping allowed us to create an accurate 1:1 model of a biological object hidden by wrappings. This model can be used to study skeletal features and morphology and also enhance exhibitions hosted within the museum. Originality/value – This is the first replica of its kind made of an ancient Egyptian falcon mummy skeleton. The combination of computed tomography scanning and 3D printing has the potential to facilitate scientific research and stimulate public interest in Egyptology.

scholarly journals APPROPRIATE MODELS FOR SIMULATING OPEN-POROUS MATERIALS

2017 ◽  
Vol 36 (2) ◽  
pp. 107 ◽  
Author(s):  
Tomasz Wejrzanowski ◽  
Samih Haj Ibrahim ◽  
Jakub Skibinski ◽  
Karol Cwieka ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Porous Materials ◽  
Pore Size ◽  
Open Porosity ◽  
Diameter Distribution ◽  
Cell Diameter ◽  
Micro Computed Tomography ◽  
Open Cell ◽  
Geometrical Features ◽  
Open Cell Foams ◽  
Number Of Faces

In the present paper two representative models applied for modeling of two types of porous materials - open-cell foams and open-porosity tapes - are addressed. Algorithms presented here base on Laguerre-Voronoi tessellations (open-cell foams) and the sphere representation (open-porosity tapes) and enable creating the desired porosity and pore size distribution. The geometrical features of the models, such as: porosity, mean pore size, cell diameter distribution and number of faces per cell were compared with those obtained by 3D micro-computed tomography and good agreement was obtained.

scholarly journals Breaking the mould: achieving high-volume production output with additive manufacturing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yuan Huang ◽  
Daniel R. Eyers ◽  
Mark Stevenson ◽  
Matthias Thürer
Keyword(s):  
Additive Manufacturing ◽  
Operations Management ◽  
Economies Of Scale ◽  
Management Practices ◽  
Low Cost ◽  
High Volume ◽  
Abductive Reasoning ◽  
Disruptive Technology ◽  
Content Type ◽  
New Research

PurposeThe study aims to examine a discrepant industrial case that demonstrates how to achieve economies of scale with additive manufacturing (AM), thereby expanding the scope of AM beyond high-variety, customised production contexts.Design/methodology/approachAbductive reasoning is applied to analyse a case of using AM to compete with conventional production, winning a contract to supply 7,700,000 products. Comparing this case to existing theories and contemporary practices reveals new research directions and practical insights.FindingsEconomies of scale were realised through a combination of technological innovation and the adoption of operations management practices atypical of AM shops (e.g. design for volume, low-cost resource deployment and material flow optimisation). The former improved AM process parameters in terms of time, cost and dependability; the latter improved the entire manufacturing system, including non-AM operations/resources. This system-wide improvement has been largely overlooked in the literature, where AM is typically viewed as a disruptive technology that simplifies manufacturing processes and shortens supply chains.Originality/valueIt is empirically shown that an AM shop can achieve economies of scale and compete with conventional manufacturing in high-volume, standardised production contexts.

Correlation between porosity and permeability of stainless steel filters with gradient porosity produced by SLS/SLM

2020 ◽  
Vol 26 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Aloysio Arthur Becker Fogliatto ◽  
Carlos Henrique Ahrens ◽  
Paulo Antônio Pereira Wendhausen ◽  
Edson Costa Santos ◽  
Daniel Rodrigues
Keyword(s):  
Stainless Steel ◽  
Process Parameters ◽  
Steel Powder ◽  
Functionally Graded ◽  
Porous Structures ◽  
Micro Computed Tomography ◽  
Retention Capacity ◽  
Content Type ◽  
Porosity And Permeability ◽  
The Relationship

Purpose Porous structures have been widely used in filtration, medical implants and aerospace field. In the filtration field, the study of permeability of the porous structures is of great importance. This paper aims to study the influence of selective laser sintering/melting (SLS/SLM) process parameters on porosity and permeability of stainless steels filters with gradient porosity (FGM). Design/methodology/approach AISI 316L stainless steel powder was used to manufacture FGM filters by varying the hatch distance while other process parameters were fixed. The relationship between porosity and permeability of such FGM filters was investigated by means of Archimedes’ and Forchheimer’s laws. The gradient of porosity was also analyzed by means of micro-computed tomography. Findings The results have confirmed the ability of SLS/SLM in controlling porosity of the final product by varying the hatch distance. Further, the results allow to assume that FGM filters will have particle retention capacity related to lowest porosity value (which in turn is associated with the lowest hatch distance value used), while it will work at lower pressure drops – or at higher flow rates for equal pressure drop – when compared to a filter without gradient porosity. Originality/value Some research found in recent literature has showed the relationship between SLS/SLM process parameters and permeability of stainless steel porous structures. However, this paper fulfils the need to understand the relationship between SLS/SLM process parameters, porosity and permeability behavior of functionally graded porous structures (FGM filters).

scholarly journals A rapid, accurate, scalable, and portable testing system for COVID-19 diagnosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guanhua Xun ◽  
Stephan Thomas Lane ◽  
Vassily Andrew Petrov ◽  
Brandon Elliott Pepa ◽  
Huimin Zhao
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
High Volume ◽  
N Gene ◽  
Testing System ◽  
Target Sequence ◽  
One Pot ◽  
Sequence Detection ◽  
Highly Sensitive ◽  
Speed Accuracy

AbstractThe need for rapid, accurate, and scalable testing systems for COVID-19 diagnosis is clear and urgent. Here, we report a rapid Scalable and Portable Testing (SPOT) system consisting of a rapid, highly sensitive, and accurate assay and a battery-powered portable device for COVID-19 diagnosis. The SPOT assay comprises a one-pot reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP) followed by PfAgo-based target sequence detection. It is capable of detecting the N gene and E gene in a multiplexed reaction with the limit of detection (LoD) of 0.44 copies/μL and 1.09 copies/μL, respectively, in SARS-CoV-2 virus-spiked saliva samples within 30 min. Moreover, the SPOT system is used to analyze 104 clinical saliva samples and identified 28/30 (93.3% sensitivity) SARS-CoV-2 positive samples (100% sensitivity if LoD is considered) and 73/74 (98.6% specificity) SARS-CoV-2 negative samples. This combination of speed, accuracy, sensitivity, and portability will enable high-volume, low-cost access to areas in need of urgent COVID-19 testing capabilities.

scholarly journals Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 523-540
Author(s):  
Imed Beghoura ◽  
Joao Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Size ◽  
Physical And Mechanical Properties ◽  
Critical Parameters ◽  
Porous Structures ◽  
Foaming Agent ◽  
Al Powder ◽  
Highly Porous ◽  
Alkali Activated

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.

scholarly journals Engineering and Manufacturing Technology of Green Epoxy Resin Coatings Modified with Recycled Fine Aggregates

2021 ◽  
Author(s):  
Kamil Krzywiński ◽  
Łukasz Sadowski ◽  
Damian Stefaniuk ◽  
Aleksei Obrosov ◽  
Sabine Weiß
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Construction And Demolition Waste ◽  
Fine Aggregate ◽  
Micro Computed Tomography ◽  
Demolition Waste ◽  
Replacement Ratio ◽  
Recycled Fine Aggregate ◽  
Fine Aggregates ◽  
Computed Tomography Scanning

AbstractNowadays, the recycled fine aggregate sourced from construction and demolition waste is not frequently used in manufacturing of epoxy resin coatings. Therefore, the main novelty of the article is to prepare green epoxy resin coatings modified with recycled fine aggregate in a replacement ratio of natural fine aggregate ranged from 20 to 100%. The microstructural properties of the aggregates and epoxy resin were analyzed using micro-computed tomography, scanning electron microscopy and nanoindentation. The macroscopic mechanical properties were examined using pull-off strength tests. The highest improvement of the mechanical properties was observed for epoxy resin coatings modified with 20% of natural fine aggregate and 80% of recycled fine aggregate. It has been found that even 100% of natural fine aggregate can be successfully replaced using the recycled fine aggregate with consequent improvement of the pull-off strength of analyzed epoxy resin coatings. In order to confirm the assumptions resulting from the conducted research, an original analytical and numerical failure model proved the superior behavior of modified coating was developed.

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