Multivariable Regression Analysis for Optimised Mass Calculation of MEX 3D Printed Parts

Since its introduction in the early 1990s Material Extrusion (MEX) has become the most popular additive manufacturing technology for a variety of applications. One of the reasons of its popularity amongst users is the affordability of the equipment, materials and the open source software. Given the large variety of combinations optimisation of MEX process parameters can be quite elaborate. The paper provides a method for optimisation of mass calculation using multivariable regression analysis. Layer thickness, printing temperature and printing speed were considered the independent variables for a two level factorial experimental program. DOE was used to plan 12 sets of programs, out of which four were found to have significant models. The four models were validated through measured and calculated responses

Design and Additive Manufacturing of a Medical Face Shield for Healthcare Workers Battling Coronavirus (COVID-19)

During the coronavirus disease-19 pandemic, the demand for specific medical equipment such as personal protective equipment has rapidly exceeded the available supply around the world. Specifically, simple medical equipment such as medical gloves, aprons, goggles, surgery masks, and medical face shields have become highly in demand in the health-care sector in the face of this rapidly developing pandemic. This difficult period strengthens the social solidarity to an extent parallel to the escalation of this pandemic. Education and government institutions, commercial and noncommercial organizations and individual homemakers have produced specific medical equipment by means of additive manufacturing (AM) technology, which is the fastest way to create a product, providing their support for urgent demands within the health-care services. Medical face shields have become a popular item to produce, and many design variations and prototypes have been forthcoming. Although AM technology can be used to produce several types of noncommercial equipment, this rapid manufacturing approach is limited by its longer production time as compared to conventional serial/mass production and the high demand. However, most of the individual designer/maker-based face shields are designed with little appreciation of clinical needs and nonergonomic. They also lack of professional product design and are not designed according to AM (Design for AM [DfAM]) principles. Consequently, the production time of up to 4 – 5 h for some products of these designs is needed. Therefore, a lighter, more ergonomic, single frame medical face shield without extra components to assemble would be useful, especially for individual designers/makers and noncommercial producers to increase productivity in a shorter timeframe. In this study, a medical face shield that is competitively lighter, relatively more ergonomic, easy to use, and can be assembled without extra components (such as elastic bands, softening materials, and clips) was designed. The face shield was produced by AM with a relatively shorter production time. Subsequently, finite element analysis-based structural design verification was performed, and a three-dimensional (3D) prototype was produced by an original equipment manufacturer 3D printer (Fused Deposition Modeling). This study demonstrated that an original face shield design with <10 g material usage per single frame was produced in under 45 min of fabrication time. This research also provides a useful product DfAM of simple medical equipment such as face shields through advanced engineering design, simulation, and AM applications as an essential approach to battling coronavirus-like viral pandemics

Determination of Time Dependent Stress Distribution on Potato Tubers at Mechanical Collision

This study focuses on determining internal stress progression and the realistic representation of time dependent deformation behaviour of potato tubers under a sample mechanical collision case. A reverse engineering approach, physical material tests and finite element method (FEM)-based explicit dynamics simulations were utilised to investigate the collision based deformation characteristics of the potato tubers. Useful numerical data and deformation visuals were obtained from the simulation results. The numerical results are presented in a format that can be used for the determination of bruise susceptibility magnitude on solid-like agricultural products. The modulus of elasticity was calculated from experimental data as 3.12 [MPa] and simulation results showed that the maximum equivalent stress was 1.40 [MPa] and 3.13 [MPa] on the impacting and impacted tubers respectively. These stress values indicate that bruising is likely on the tubers. This study contributes to further research on the usage of numerical-methods-based nonlinear explicit dynamics simulation techniques in complicated deformation and bruising investigations and industrial applications related to solid-like agricultural products

Study regarding the influence of material type on economic objectives in MEx fabrication

Material Extrusion has been used extensively as an additive manufacturing technology for a variety of applications like visual models, functional prototypes, tooling components, patterns for castings, and final parts. The current research paper proposes a study on the material type influence on economic objectives in material extrusion fabrication of complex assemblies. Three economic objectives have been analysed, namely, estimated fabrication time, material usage and material cost, whilst two commercial additive manufacturing machines have been considered for the simulation. Cura and ZSuite slicing software were used for the generation of Gcode and project files. Five filaments were selected from the same manufacturer and all components of the selected assembly were included in the analysis. Throughout the study, the additive manufacturing parameters were kept constant, as well as the component layout on the build platform of the two machines. Study results were analysed in correspondence with the manufacturing requirements and the optimum fabrication scenario was selected. Further research includes the analysis of multiple material manufacturers, in order to evaluate the influence of chemical composition on economic outputs

University Brand Management through Additive Manufacturing Applications

Brand management is vital for identity development of any educational entity. The paper proposes a brand management strategy developed for a large university using several additive manufacturing applications. A product design and development team identified the need for brand establishment through identity promotion of the universities’ unique capabilities. Several concepts were generated and analysed in accordance with product requirements and restrictions. After technology selection, the selected product was a key chain manufactured with Fused Deposition Modelling. To expand the product portfolio and thus the range of proactive actions within the branding process, two more products were selected for manufacture. Open cast epoxy resin medals and open cast chocolate candies required the development of specialised RTV silicone moulds. Branding management was done in strict correlation with the developed products. Various proactive, reactive and mixed actions were developed and implemented throughout the course of one academic year, targeting short, medium and long term results. The branding campaign included the modification of some study programs, the development of interactive demo shows and implementation of open days. Future research is targeted at ensuring sustainability of the proposed brand management strategy

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity

New Tracheostomy Device Concept:An Additive Manufacturing Challenge in Reducing Late Clinical Complications

The application of additive manufacturing technologies for the development of invasive airway devices may enhance the quality of life of tracheostomy patients. The current research is intended to reduce clinical long-term complications that appear in the frequent use of classic tracheostomy tubes in airway management. The development of a bespoke tracheostomy device aims to improve functional ability, social anxiety and overall patient satisfaction. The study was conducted in four stages: preconception, patient specific design, additive manufacturing of the new endotracheal tube prototype and testing. Using patient specific data a new concept was designed with appropriate CAD software, while implementing the findings from deploying functional analysis. Starting with a cuffed tracheostomy tube for needs analysis, three new CAD models were generated. The initial functional prototypes were developed, with the main innovations brought to the tracheal fixing system, neck plate and obturator, and were enabled by the advantages of additive manufacturing technologies. Initial tests were undertaken on an explanted pigs’ trachea with the aim of identification of any surgical technique or concept shape related problems. The current research presents an integrated approach for developing a new tracheostomy device concept, fabricated using AM technologies. The advantages of AM were used to enable the design and manufacture of customised, unique features that target the reduction of late clinical complications of tracheostomy tube users

Mass optimisation of 3D-printed specimens using multivariable regression analysis

Fused deposition modelling popularity is attributed to equipment affordability, materials availability and open-source software. Given the variety of optimisation combinations, process parameters can be elaborate. This paper provides methods for optimisation of mass calculation using multivariable regression analysis. Layer thickness, extrusion temperature and speed were considered independent variables for a two-level factorial experiment. DOE was used for 12 sets of programs and analysis (two stages) undertaken using Design-Expert® V11 Software. In stage-1, four models were found to be significant. Stage-2 involved redesigning the remaining eight models, iteratively increasing the number of replicates and blocks. Adequacy of models was analysed, demonstrating that: model is significant, F-value is large, p 4.00; residuals are well behaved; R^2 is as close as possible to 1.00 or for models with multiple replicates, the adjusted R^2 and predicted R^2 differential <0.2. All models were validated through measured, calculated responses