Aluminum and aluminum-alumina powder mixtures were used to produce pyramidal fin arrays on aluminum substrates using cold spray as an additive manufacturing process. Using aluminum-alumina mixtures instead of pure aluminum powder could be seen as a cost-effective measure, preventing nozzle clogging. The fin geometries that were produced were observed using a 3D digital microscope to determine the flow passages width and fins geometric details. Heat transfer and pressure tests were carried out using different ranges of appropriate Reynolds numbers for the sought commercial application to compare each fin array and determine the effect of alumina content. It was found that the presence of alumina reduces the fins’ performance when compared to pure aluminum but that they still outperform traditional fins. Numerical simulations were performed and were used to explain the obtained experimental results. The numerical model opens up new avenues in predicting different parameters such as pressure and substrate temperature.

As órteses de membro superior são dispositivos que auxiliam na reabilitação da mão e que tem como objetivo estabilizar, imobilizar, prevenir e corrigir deformidades, melhorando assim a função. O processo tradicional de confecção de órteses é realizado por meio do uso de termoplásticos de baixa temperatura, material moldado diretamente sobre o membro do usuário, sendo neste processo relatados inúmeros problemas, que envolvem desconforto durante o processo, alto custo e baixa adesão do paciente ao uso. O presente trabalho, portanto, teve por objetivo propor a construção de um framework com abordagem metodológica projetual para a produção de órteses de membro superior baseada no processo de design e design colaborativo, com auxílio de recursos de fabricação digital, como digitalização tridimensional e manufatura aditiva (impressão 3D). Através de uma pesquisa exploratória, foram discutidas questões relativas ao projeto de órteses de membro superior (MMSS) pela forma tradicional, utilizando termoplástico de baixa temperatura, e questões do processo de design no desenvolvimento de novos produtos a serem aplicadas do desenvolvimento de órteses utilizando a manufatura aditiva A coleta de dados contou com a participação dos principais personagens envolvidos no processo, usuários de órteses, Terapeutas Ocupacionais e Designers. Com base na técnica de card sorting e entrevistas, foi elaborado um framework da abordagem projetual para a criação de órteses utilizando processos de fabricação digital, de forma colaborativa. O framework ainda foi aplicado no desenvolvimento de uma órtese a fim de avaliar os resultados e melhorias levantadas durante a fase de entrevistas com profissionais e usuários. Ao final do processo, obteve-se uma órtese funcional em que foram atendidos os requisitos necessários para a produção de uma órtese levantada pelo trabalho, além da criação do framework servindo como um guia para o desenvolvimento de órteses utilizando a manufatura aditiva. / Upper limb orthoses are devices that assist in the rehabilitation of the hand and that aim to stabilize, immobilize, prevent and correct deformities, thus improving the function. The traditional process of making orthotics is accomplished through the use of thermoplastics of low temperature, molded material directly on the member of the user, being in this process reported numerous problems, that involve discomfort during the process, high cost and low adhesion of the patient to the use. The present work, therefore, aimed to propose the construction of a framework with a design methodological approach for the production of upper limb orthosis based on the process of design and collaborative design, with the aid of digital manufacturing resources such as three - dimensional digitization and additive manufacturing (3D printing). Through an exploratory research, questions regarding the design of upper limb orthoses (MMSS) in the traditional way, using low-temperature thermoplastic, and design process issues in the development of new products to be applied in the development of orthoses using the additive manufacture The data collection was attended by the main characters involved in the process, users of orthoses, Occupational Therapists, and Designers. Based on the technique of card sorting and interviews, a framework of the design approach for the creation of orthoses using digital manufacturing processes was developed in a collaborative way. The framework was also applied in the development of a bracing in order to collaborate with the results and improvements raised during the interviews phase with professionals and users. At the end of the process, a functional orthosis was obtained, in which the necessary requirements for the production of an orthosis were obtained by the work, besides the creation of a framework serving as a guide for the development of orthoses using the additive manufacture.

Additive manufacturing processes of many alloys are known to develop texture during the deposition process due to the rapid reheating and the directionality of the dissipation of heat. Titanium alloys and with respect to this study beta titanium alloys are especially susceptible to these effects. This work examines Ti-20wt%V and Ti-12wt%Mo deposited under normal additive manufacturing process parameters to examine the texture of these beta-stabilized alloys. Both microstructures contained columnar prior beta grains 1-2 mm in length beginning at the substrate with no visible equiaxed grains. This microstructure remained constant in the vanadium system throughout the build. The microstructure of the alloy containing molybdenum changed from a columnar to an equiaxed structure as the build height increased. Eighteen additional samples of the Ti-Mo system were created under different processing parameters to identify what role laser power and travel speed have on the microstructure. There appears to be a correlation in alpha lath size and power density. The two binary alloys were again deposited under the same conditions with the addition of 0.5wt% boron to investigate the effects an insoluble interstitial alloying element would have on the microstructure. The size of the prior beta grains in these two alloys were reduced with the addition of boron by approximately 50 (V) and 100 (Mo) times.

Orientador: João Eduardo Guarnetti dos Santos / Resumo: O ombro por ser uma articulação muito instável está mais vulnerável a lesões. Afim de proteger e imobilizar a articulação o tratamento é seguido com o uso de tipoia. No entanto, a imobilização deixa as articulações sob os efeitos deletérios do desuso, o que pode favorecer o surgimento de lesões secundárias como a capsulite adesiva. O design e a ergonomia são considerados disciplinas científicas capazes de desenvolver e ajustar produtos às necessidades e às capacidades humanas. O objetivo deste estudo foi gerar parâmetros para o design ergonômico de uma tipoia alternativa utilizando as tecnologias de manufatura aditiva, a fim de minimizar os desconfortos termofisiológicos e o índice de capsulite adesiva após imobilização. Nesse contexto, desenvolveu-se com o auxílio do design um modelo de tipoia mais confortável, adequado, funcional e que não favorece o surgimento de complicações após imobilização do ombro. Foi realizada uma coleta de dados com indivíduos adultos, de ambos os gêneros, entre 18 e 85 anos de idade, 71 voluntários, que fizeram uso de tipoia para lesão do ombro. Seguiu com uma investigação ergonômica dos modelos de tipoia disponíveis no mercado, para desenvolver um modelo alternativo com as devidas adequações ergonômicas. O projeto da tipoia foi modelado no software CAD SolidWorks e a impressão foi por FDM (Fusão por Deposição de Material), em uma impressora 3D Creality CR-10, com material PLA (Ácido Polilactico). Para testar a percepção do usuário frente aos mode... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The shoulder because it is a very unstable joint is more vulnerable to injury, in order to protect and immobilize the joint, treatment is followed with the use of a sling. However, immobilization leaves the joints under the harmful effects of disuse, which can favor the appearance of secondary lesions such as adhesive capsulitis. Design and ergonomics are considered scientific disciplines capable of developing and adjusting products to human needs and capacities. The aim of this study was to generate parameters for the ergonomic design of an alternative sling using additive manufacturing technologies, in order to minimize thermophysiological discomfort and the adhesive capsulitis index after immobilization. In this context, a more comfortable, adequate, functional tipoia of model was developed with the aid of design, which does not favor the appearance of complications after shoulder immobilization. A data collection was carried out with adult individuals, both genders, between 18 and 85 years of age, 71 volunteers, who made use of tipoia for shoulder injury. It continued with an ergonomic investigation of the sling models available on the market, to develop an alternative model with the appropriate ergonomic adaptations. The design of the tipoia was modeled in SolidWorks CAD software and the printing was by FDM (Melting by Deposition of Material) in a Creality CR-10 3D printer with PLA material (Polylactic Acid). To test the user's perception of sling models, a semantic diff... (Complete abstract click electronic access below) / Doutor

abstract: Additive manufacturing (AM) has been extensively investigated in recent years to explore its application in a wide range of engineering functionalities, such as mechanical, acoustic, thermal, and electrical properties. The proposed study focuses on the data-driven approach to predict the mechanical properties of additively manufactured metals, specifically Ti-6Al-4V. Extensive data for Ti-6Al-4V using three different Powder Bed Fusion (PBF) additive manufacturing processes: Selective Laser Melting (SLM), Electron Beam Melting (EBM), and Direct Metal Laser Sintering (DMLS) are collected from the open literature. The data is used to develop models to estimate the mechanical properties of Ti-6Al-4V. For this purpose, two models are developed which relate the fabrication process parameters to the static and fatigue properties of the AM Ti-6Al-4V. To identify the behavior of the relationship between the input and output parameters, each of the models is developed on both linear multi-regression analysis and non-linear Artificial Neural Network (ANN) based on Bayesian regularization. Uncertainties associated with the performance prediction and sensitivity with respect to processing parameters are investigated. Extensive sensitivity studies are performed to identify the important factors for future optimal design. Some conclusions and future work are drawn based on the proposed study with investigated material. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2020

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Silicon carbide is a useful monolithic and matrix ceramic due to its excellent mechanical properties and corrosion/oxidation resistance at high temperature. This makes it an attractive material for use in advanced applications, such as aircraft engines and high-speed flight. In this study, additively manufactured monolithic SiC and Cf/SiC CMCs, processed via direct ink writing (DIW) of a 53 vol% colloidal suspension, achieved >96% theoretical density through pressureless sintering. When present, fibers are aligned in the direction of the print path. Five different print paths were studied, including a 0o path, 90o path, 0/90o path, 0/15/30/45/60/75/90o path, and 0/30/60/90/60/30/0o path. Four-point bend testing was performed to determine flexural strength and Weibull analysis was performed. Strengths were highest for the 0o print path. The characteristic strength, σo, of this print path was 375 MPa with a Weibull modulus of 7.4 for monolithic SiC and a σo of 361 MPa with a Weibull modulus of 10.7 for Cf/SiC. Weibull modulus was greater for Cf/SiC samples compared to identically printed monolithic SiC samples. SEM and optical microscopy were used to analyze printed parts which showed a high degree of fiber alignment in the direction of the print. Fiber pullout was observed on the fracture surface, as well as intragranular fracture.

Selective laser melting (SLM) is a new and rapidly developing manufacturing method for producing full-density, geometrically complex metal parts. The SLM process is time and cost effective for small-scale production; however, wide-spread adoption of this technique is severely limited by residual stresses that can cause large deformations and in-process build failures. The issues associated with residual stress accumulation are most apparent in parts with overhanging features. Due to the complexity of the SLM process, the accumulation of residual stresses is difficult to assess a priori. The deformations and in-process failures caused by residual stress accumulation often lead to an expensive and time consuming iterative manufacturing process. To aid in the development of general SLM design guidelines for overhanging features, the effect of varying two support structure design parameters on residual stress accumulation were investigated. A part-scale thermo-mechanical finite element model was implemented using Diablo, a multi-physics finite element code developed by Lawrence Livermore National Laboratory (LLNL), and trends observed in the model were validated experimentally. By comparing the distribution and magnitude of residual stresses, it was determined that reducing cooling rate gradients in overhanging features reduces the resulting residual stresses. Additionally, it was shown that volume effective material properties can be used to reduce computational costs in computational models of the SLM process.

Alla ska ha lika stor möjlighet att utöva idrott på lika villkor. Parasport är idrott till för personer med någon form av funktionsnedsättning såsom synnedsättning, intellektuell funktionsnedsättning eller rörelsenedsättning. Inom parasport finns alpin skidåkning som går ut på att ta sig ned för backen så snabbt som möjligt i en utstakad bana. Utbudet av professionell utrustning för både alpint och andra sporter som är möjlig att individanpassa mot idrottsutövarens behov är mycket begränsad om än inte obefintlig. Projektet initierades av landslagstränaren för alpina parasportförbundet, Henrik Bergqvist. Syftet med detta projekt är att möjliggöra en bättre tackling av en slalomkäpp för paraalpinåkare med förkortad underarm. Målet med projektet är att ta fram ett konceptunderlag för att kunna tillverka ett alpint slalomarmskydd. Konceptunderlaget kommer innefatta tredimensionella ritningar för produkten samt materialval och tillverkare. Denna rapport omfattar en produktutvecklingsprocess innehållande fem faser, förstudie, produktspecificering, konceptgenerering, utvärdering och val av koncept, prototyp och detaljkonstruktion. Resultatet av projektet genererades i ett konceptunderlag för ett slalomarmskydd till paraalpinåkare med förkortad underarm. Detta koncept har funktionen att tackla bort slalomkäppen samtidigt som den ska vara ergonomisk mot underarmen, och ha ett material som tål de påfrestningar som skyddet kommer utsättas för. Projektet och dess resultat överlämnas till uppdragsgivaren med goda förutsättningar att vidare kunna tillverka detta slalomarmskydd. / Everyone should have an equal opportunity to practice sports on equal terms. Parasport is sports for people with some form of disability such as visual impairment, intellectual disabilities or mobility impairment. In parasport, there is alpine skiing that involves getting down the slope as quickly as possible in a marked course. The range of professional equipment for both alpine and other sports that can be individually adapted to the athlete's needs is very limited, although not non-existent.   The project was initiated by the national team coach for the alpine parasport association, Henrik Bergqvist. The purpose of this project is to enable a better tackle of a slalom gate for para-alpine skiers with a shortened forearm. The goal of the project is to produce a concept material to be able to manufacture an alpine slalom arm guard. The concept material will include three-dimensional drawings for the product as well as material selection and manufacturers.   This report covers a product development process that includes five phases, feasibility study, product specification, concept generation, evaluation and selection of concepts, prototype and detailed design.   The result of the project was generated in a concept data for a slalom arm protection for para-alpine skiers with a shortened forearm. This concept has functions to tackle the slalom gate while at the same time being ergonomic against the forearm and having a material that can withstand the stresses to which the protection will be exposed.   The project and its results are handed over to the client with good conditions to be able to further manufacture this slalom arm guard. / <p>Betyg 2021-07-16</p>