Investigating the effects of printing temperatures and deposition on the compressive properties and density of 3D printed polyetheretherketone

Open access funding provided by FCT|FCCN (b-on). Publisher Copyright: © 2023, The Author(s).Polyetheretherketone (PEEK) is a biocompatible high-performance thermoplastic that can be processed through material extrusion (ME) additive manufacturing (AM) for load-bearing implant applications. In this work, density measurements and compression testing were used to investigate the relation between printing temperatures and deposition patterns of PEEK 3D printed samples. Different deposition patterns were tested with different nozzle and zone heater temperatures to observe how the heat input from the printing process influenced the deposition stability with different nozzle paths. Compression test results showed that samples with concentric-based deposition patterns resulted in higher compressive yield strength and modulus than the rectilinear samples. These results were correlated with the samples’ void contents estimated from density measurements. Both the highest 0.2% offset yield strength of 100.3 MPa and the highest modulus of 3.58 GPa were obtained with an interlayer offset deposition which resulted in reductions in estimated void contents between 48 and 72% in relation to concentric deposition. Different printing temperatures and deposition sequences were tested, where higher printing temperatures resulted in lower yield strength and stiffness. Alternating deposition between the outer and inner lines of the concentric pattern resulted in a reduction of about 43% in void contents and increased elastic modulus and yield strength from 3.12 to 3.40 GPa and 94.4 to 95.2 MPa respectively. The results from this work suggest that the relation between printing temperatures and deposition strategy for different print geometries plays a significant role in the ME-AM of PEEK for high-performance applications.publishersversionepub_ahead_of_prin

A score methodology to assess concept maps in medical education in the context of pathophysiology teaching

The main objective of pathophysiology teaching is to facilitate the learning of mechanisms of diseases and the understanding of their expressions in patients (symptoms, signs and tests). This objective requires the application of basic biomedical science to explain the abnormalities expressed by the patients. The capacity to integrate this new organization of knowledge is essential to the understanding of pathophysiological mechanisms, which explain expressions of specific diseases. Our group has a longstanding experience in the teaching of pathophysiology to medical students using problem-based learning (PBL) and concept mapping (CM). This semestral discipline has a yearly intake of 190 students, divided into 18 tutorial groups and supported by 14 tutors. The students’ learning progress is evaluated by their performance during the tutorial sessions and the CM methodology has been introduced as an additional tool to visualize the integration of knowledge and how it is displayed in the different pathophysiological mechanisms. Until now, the evaluation of CM has been qualitative and used as an additional assessment tool by the tutors. This study reports how we are changing this approach by training the tutors and developing a scoring methodology, which will be described in detail, together with a preliminary application in selected mapsFonseca, M.; Oliveira, B.; Carreiro-Martins, P.; Neuparth, N.; Rendas, A. (2020). A score methodology to assess concept maps in medical education in the context of pathophysiology teaching. En 6th International Conference on Higher Education Advances (HEAd'20). Editorial Universitat Politècnica de València. (30-05-2020):867-874. https://doi.org/10.4995/HEAd20.2020.11163OCS86787430-05-202

a qualitative approach

Funding Information: This study did not apply for any funding. Open access funding provided by Funda\u00E7\u00E3o Ci\u00EAncia e Tecnologia, IP national support through Comprehensive Health Research Centre (UIDP/04923/2020). Publisher Copyright: © The Author(s) 2024.Clinical reasoning is a crucial skill for physicians, enabling them to bridge theoretical knowledge with practical application. The gap between basic sciences and clinical practice persists as a challenge, with traditional teaching methods yet to effectively bridge it. Concept maps (CMs), visual tools for organizing and connecting knowledge, hold promise for enhancing clinical reasoning in the undergraduate medical curriculum. However, further research is required to ascertain if CMs facilitate clinical reasoning development in medical students transitioning from basic sciences to clinical practice. This study aims to delineate how CMs can facilitate clinical reasoning in patients with multimorbidity within undergraduate Family Medicine curricula, as perceived by students and tutors, and to understand the implementation process and resources required. This exploratory qualitative study formed a part of an action research project. While introducing an educational intervention to 5th-year medical students, we conducted a qualitative evaluation. Subsequently, semi-structured group interviews were conducted with students, and a focus group was conducted with tutors. Three main educational impacts were identified: integration of clinical information, support for patient management and care plan, and collaborative learning. Key aspects for successful CM implementation included clear instructions for map construction, using user-friendly software, allocating sufficient time for the task, encouraging group discussion of CMs, and incorporating tutor feedback. CMs are pedagogical tools that facilitate clinical information integration and support management and treatment plans, helping students better understand multimorbidity patients and promoting some components of clinical reasoning in undergraduate medical education.publishersversioninpres

Improvement of tensile and flexural properties of 3D printed PEEK through the increase of interfacial adhesion

The authors acknowledge Fundação para a Ciência e a Tecnologia (FCT, I.P.) for its financial support through the PhD scholarship UI/BD/151082/2021 and through UNIDEMI, project UIDB/00667/2020. The authors would also like to thank João O. Cardoso for the support provided with the DSC analysis equipment.Polyetheretherketone (PEEK) is the leading high-performance biocompatible thermoplastic for the replacement of metals in orthopaedic applications. PEEK processing using material extrusion (ME) Additive Manufacturing (AM) techniques such as Fused Filament Fabrication (FFF) highlight its potential for the manufacture of patient-specific load-bearing implantable medical devices. As a high temperature semi-crystalline polymer, the mechanical properties of PEEK 3D printed samples are significantly influenced by printing parameters, particularly the crystallinity and interfacial adhesion of 3D printed parts. Given these challenges, the printing parameters of nozzle temperature, zone heater temperature, layer height and extruder multiplier were selected and studied for their effects in the interfacial adhesion and thus consequent mechanical performance of PEEK 3D prints. Design of Experiment (DoE) studies were conducted where the Taguchi and ANOVA analysis were used to determine the optimal parameter combinations and respective contributions. Additionally, different infill configurations were used with the optimal parameters to lower the samples' void volume and increase interface bonding. Reductions of up to 65 % in void volume were obtained with an interlayer translation of the infill lines and the tested configurations yielded improvements in both the tensile and flexural properties of 3D printed PEEK. Furthermore, high-temperature annealing treatments produced further increases in the strength, stiffness and crystallinity of PEEK samples. With this, significant improvements in both the void volume and the tensile and flexural properties of PEEK prints were achieved in support of the use of 3D printed PEEK in the manufacture of custom-made and high performance implantable medical devices.publishersversionpublishe

High-Cycle Fatigue Behaviour of Polyetheretherketone (PEEK) Produced by Additive Manufacturing

Publisher Copyright: © 2023 by the authors.Polyetheretherketone (PEEK) is the leading high-performance thermoplastic biomaterial that can be processed through material extrusion (ME) additive manufacturing (AM), also known as three-dimensional (3D) printing, for patient-specific load-bearing implant manufacture. Considering the importance of cyclic loading for load-bearing implant design, this work addresses the high-cycle fatigue behaviour of 3D-printed PEEK. In this work, printed PEEK specimens are cyclically loaded under stress-controlled tension–tension using different stress levels between 75% and 95% of printed PEEK’s tensile strength. The experimental results are used to document 3D-printed PEEK’s fatigue behaviour using Basquin’s power law, which was compared with previous fatigue research on bulk PEEK and other 3D-printing materials. As a pioneering study on its fatigue behaviour, the results from this work show that 3D-printed PEEK exhibits an above-average fatigue strength of 65 MPa, corresponding to about 75% of its tensile strength. Fracture surface analysis suggests that a transition can occur from ductile to brittle fracture with maximum stresses between 85% and 95% of the tensile strength. Evidence of crack propagation features on fracture surfaces under scanning electron microscope (SEM) observation suggests crack initiation in void defects created by printing deposition that propagates longitudinally through line bonding interfaces along layers. Considering this, 3D-printed PEEK’s fatigue behaviour can be strongly related to printing conditions. Further research on the fatigue behaviour of 3D-printed PEEK is necessary to support its use in load-bearing implant applications.publishersversionpublishe

A concept map template to be used by medical students for displaying pathophysiological mechanisms within clinical cases

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A scoping review comparing different mapping approaches pointing to the need for standardizing concept maps in medical education: A preliminary analysis

This study aims to analyze how visual tools, labeled as maps, are built, and used in medical education. Based on the educational model of concept maps (CMs), proposed by Novak and Cañas (2008), and adapted to medicine by Daley and Torre (2010), we are currently analyzing the results of a scoping review following the PRISMA extension methodology, specifically for these purposes. Other visual tools, such as knowledge maps (KMs) and mind maps (MMs), used in medical education, were also included. The search was made through the databases EBSCO, PubMed/MEDLINE, PsycINFO, Scopus, and Eric, using the following items: “concept map*”, “knowledge map*”, “mind map*” and “medical education”. Only articles in English were considered and exclusively in medical education, from undergraduate to resident training. The analysis of selected articles included the following features: construction rules (if they followed Novakian instructions), teaching area, student level (undergraduate, postgraduate/residents), and use for assessment. Other features were the capacity to relate basic science knowledge to clinical concepts, the use of maps with other educational methods, such as problem-based learning (PBL), and providing feedback to students. From a quantitative perspective, the use of CMs is dominant in all phases of medical education. A failure to follow Novakian rules was found in around half of the articles labeled as CMs and KMs. As for MMs, which follow different rules for construction and use, they were considered relevant in helping students to summarize and retain information. Simultaneous use with other educational methods was only found with CMs

Analyzing the use of linking words in concept maps designed for pathophysiology learning in medicine

[EN] Pathophysiology at NOVA Medical School adopted the concept mapping methodology to promote the visual display of pathophysiological reasoning and learning, based on clinical vignettes. The objective of this project is to identify and label the linking words, in order to study their role in the structure and organization of the concept maps constructed by the students. We used an adopted classification of linking words, categorized in 5 groups: dynamic, static, illustrative, definition and clinical case information. At the end of the semester the concept maps related to the respiratory (mid-semester) and endocrine systems (end of semester) were analyzed and compared. We found linking words not included in any of the five categories, thus a group named “other” has been created. Statistically significant differences were found in dynamic and “other” categories (p=0,049 and p= 0,011, respectively; Wilcoxon signed-rank test). The dynamic words were the most commonly used, probably reflecting students’ need to better describe pathophysiological mechanisms, and the difference found was probably due an improvement in the learning process and concept maps building technic. It would be interesting next year to conduct a more detailed analysis, increasing the sample and ensuring a more robust dataset.Grateful thanks are due to the teaching staff of pathophysiology, tutors Manuel Almeida, Patrícia Santos, Diana Ferreira, Miguel Proença, Ana Rita Franco, Luísa Quaresma, Vasco Gaspar and António Mesquita, and the junior students Sofia Ribeiro, Pedro Vilão Silva, Joana Vigeant Gomes and Margarida Flores that acted as mentors during the tutorial sessions.Fonseca, M.; Oliveira, B.; Canha, I.; Dores, H.; Pinheiro Santos, M.; Lemos, V.; Verdasca, A.... (2021). Analyzing the use of linking words in concept maps designed for pathophysiology learning in medicine. En 7th International Conference on Higher Education Advances (HEAd'21). Editorial Universitat Politècnica de València. 95-102. https://doi.org/10.4995/HEAd21.2021.13036OCS9510

Fixture Design and Process Development for High Pressure Compressor Rotor Blades Measuring in Turbofan Engine Maintenance

A TAP Maintenance and Engineering disponibiliza serviços de manutenção para motores de aviação comercial. Para tal, os diversos componentes do motor são inspecionados com o intuito de realizar sua reparação e/ou substituição de forma a restaurar alguma da performance e eficiência no consumo de combustível do motor. Nestes motores, acredita-se que o HPC (Compressor de Alta Pressão) tem um grande impacto na sua performance. Por isso, a oficina de motores da TAP tem grande interesse em adquirir conhecimentos mais aprofundados acerca da relação entre as pás do compressor de alta e os resultados de performance do motor em banco de testes. O trabalho desenvolvido procura responder a esta necessidade, disponibilizando à oficina os meios necessários para uma inspeção detalhada das dimensões das pás do compressor de alta. Desta forma, engenheiros da TAP poderão adquirir a informação necessária para estudar a correlação descrita acima e consequentemente melhorar os processos de manutenção e reparação do compressor de alta. Para este efeito, será necessária medição com recurso a uma CMM (Máquina de Medição de Coordenadas) dada a complexidade de algumas geometrias, o nível de precisão exigido por este estudo e ainda a quantidade elevada de pás que constituem o conjunto do rotor do compressor de alta. Assim o trabalho desenvolvido irá focar-se nas duas primeiras fases de implementação deste método de medição, sendo estas o desenvolvimento de modelos CAD de referência para as pás do compressor e o projeto de uma ferramenta de fixação de um conjunto de pás no plano de granito da CMM. Só depois, com base neste trabalho, será possível criar o programa de inspeção automático. Os modelos CAD das pás foram desenvolvidos no software SolidWorks a partir de uma nuvem de pontos captada por um scanner 3D, foram depois usados como referência para o projeto da ferramenta e podem ainda vir a ser essenciais para a programação da inspeção através da CMM com recurso a modelos virtuais. Adicionalmente, como a secção mais aprofundada desta tese, o projeto da ferramenta de fixação teve em conta tanto os requisitos de inspeção dimensional das pás como a própria manufatura da ferramenta. Assim, este trabalho irá também resultar na documentação necessária para a manufatura destas ferramentas permitindo à TAP iniciar o desenvolvimento do programa automático de inspeção das pás através da CMMTAP Maintenance and Engineering provides repair and overhaul services for a commercial aircraft’s engines. For this, TAP’s shop disassembles and inspects the engine’s parts to determine which repairs and replacements should be performed in order to restore the engine’s performance and fuel efficiency and meet client’s requirements. In these engine’s, the HPC (High Pressure Compressor) is thought to have a large impact in the overall engine’s performance. Concerning this, TAP Engine’s shop has great interest in better understanding the correlation between the HPC Rotor blades and the engine’s performance which could improve the results of the engine’s overhaul. This work tries to answer this by providing the shop the means to perform detailed dimensional inspection for HPC Rotor blades which will provide TAP’s engineers real data necessary to perform a correlation study between the HPC blades’ condition and the engine’s efficiency. To achieve this, a CMM (Coordinate Measuring Machine) based inspection procedure would have to be implemented given the level of detail and the sheer number of blades assembled in the HPC rotor. The work developed focuses on the first two stages of this project, the development of CAD models of the blade from each compressor stage and the design of a fixture tool to display the blades for CMM inspection. The third stage, which is only introduced in the final segment of this work, corresponds to the development of the CMM’s automatic blade inspection program. The CAD models of the blades were developed in SolidWorks software based on a point cloud obtained from a 3D scanner. These models were then used to design the fixture tools and may be essential for the CMM programming using CAD data. The fixture tools were designed to meet the blade inspection functional requirements. This design, as the more in-depth segment of this work, was developed concerning both the blade inspection procedure using the CMM and the tool’s manufacturing. This work will result in the blade’s CAD models and the correspondent fixture tools’ files for manufacturing thus providing TAP Engine Shop with the initial framework to develop the CMM inspection program