Reverse problem-based learning - a case study with a Braille machine

Engineering Education includes not only teaching theoretical fundamental concepts but also its verification during practical lessons in laboratories. The usual strategies to carry out this action are frequently based on Problem Based Learning, starting from a given state and proceeding forward to a target state. The possibility or the effectiveness of this procedure depends on previous states and if the present state was caused or resulted from earlier ones. This often happens in engineering education when the achieved results do not match the desired ones, e.g. when programming code is being developed or when the cause of the wrong behavior of an electronic circuit is being identified. It is thus important to also prepare students to proceed in the reverse way, i.e. given a start state generate the explanation or even the principles that underlie it. Later on, this sort of skills will be important. For instance, to a doctor making a patient?s story or to an engineer discovering the source of a malfunction. This learning methodology presents pedagogical advantages besides the enhanced preparation of students to their future work. The work presented on his document describes an automation project developed by a group of students in an engineering polytechnic school laboratory. The main objective was to improve the performance of a Braille machine. However, in a scenario of Reverse Problem-Based learning, students had first to discover and characterize the entire machine's function before being allowed (and being able) to propose a solution for the existing problem.

Process engineering of liver cells for drug testing applications

Dissertação para obtenção do Grau de Doutor em Bioengenharia

A systems biology framework for pathway level culture media engineering: pplication to Pichia pastoris cultures

Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica

Thermal conditions affecting heat transfer in FDM/FFE: a contribution towards the numerical modelling of the process

The performance of parts produced by Free Form Extrusion (FFE), an increasingly popular additive manufacturing technique, depends mainly on their dimensional accuracy, surface quality and mechanical performance. These attributes are strongly influenced by the evolution of the filament temperature and deformation during deposition and solidification. Consequently, the availability of adequate process modelling software would offer a powerful tool to support efficient process set-up and optimisation. This work examines the contribution to the overall heat transfer of various thermal phenomena developing during the manufacturing sequence, including convection and radiation with the environment, conduction with support and between adjacent filaments, radiation between adjacent filaments and convection with entrapped air. The magnitude of the mechanical deformation is also studied. Once this exercise is completed, it is possible to select the material properties, process variables and thermal phenomena that should be taken in for effective numerical modelling of FFE.

Impressão FDM de pares de materiais funcionais

Dissertação de mestrado integrado em Engenharia de Materiais

Influence of process parameters on part quality and mechanical properties for DMLS and SLM with iron-based materials

Rapid manufacturing is an advanced manufacturing technology based on layer-by-layer manufacturing to produce a part. This paper presents experimental work carried out to investigate the effects of scan speed, layer thickness, and building direction on the following part features: dimensional error, surface roughness, and mechanical properties for DMLS with DS H20 powder and SLM with CL 20 powder (1.4404/AISI 316L). Findings were evaluated using ANOVA analysis. According to the experimental results, build direction has a significant effect on part quality, in terms of dimensional error and surface roughness. For the SLM process, the build direction has no influence on mechanical properties. Results of this research support industry estimating part quality and mechanical properties before the production of parts with additive manufacturing, using iron-based powders

DFM(A)- aspects for a fixed electrical attenuator design

The goal of this paper is to describe a complete and extensive prototype design of a fixed electrical attenuator. The paper starts by describing the function and by giving some basic information about the attenuators. After a comprehensive description of the component, the facts of reverse engineering are discussed. The method itself is applied to ease manufacturing and design stages of this component. Information about materials and applied manufacturing technologies are also included in this report. By applying some specified DFMA-aspects the final design turned out to be a potential prototype device to be manufactured and for further analyse.

Cost evaluation process for competitors' products

A company’s capability to map out its cost position compared to other market players is important for competitive decision making. One aspect of cost position is direct product cost that illustrates the cost efficiency of a company’s product designs. If a company can evaluate and compare its own and other market players’ direct product costs, it can implement better decisions in product development and management, manufacturing, sourcing, etc. The main objective of this thesis was to develop a cost evaluation process for competitors’ products. This objective includes a process description and an analysis tool for cost evaluations. Additionally, process implementation is discussed as well. The main result of this thesis was a process description consisting of a sixteen steps process and an Excel based analysis tool. Since literature was quite limited in this field, the solution proposal was combined from many different theoretical concepts. It includes influences from reverse engineering, product cost assessment, benchmarking and cost based decision making. This solution proposal will lead to more systematic and standardized cost position analyses and result in better cost transparency in decision making.

Welding of additively manufactured stainless steel parts: Comparative study between sheet metal and selective laser melted parts

Additive manufacturing is a fast growing manufacturing technology capable of producing complex objects without the need for conventional manufacturing process planning. During the process the work piece is built by adding material one layer at a time according to a digital 3D CAD model. At first additive manufacturing was mainly used to make prototypes but the development of the technology has made it possible to also make final products. Welding is the most common joining method for metallic materials. As the maximum part size of additive manufacturing is often limited, it may sometimes be required to join two or more additively manufactured parts together. However there has been almost no research on the welding of additively manufactured parts so far, which means that there has been very little information available on the possible differences compared to the welding of sheet metal parts. The aim of this study was to compare the weld joint properties of additively manufactured parts to those of sheet metal parts. The welding process that was used was TIG welding and the test material was 316L austenitic stainless steel. Weld joint properties were studied by making tensile, bend and hardness tests and by studying the weld microstructures with a microscope. Results show that there are certain characteristics in the welds of additively manufactured parts. The building direction of the test pieces has some impact on the mechanical properties of the weld. Nevertheless all the welds exhibited higher yield strength than the sheet metal welds but at the same time elongation at break was lower. It was concluded that TIG welding is a feasible process for welding additively manufactured parts.

Digitaalisen valmistuksen vaikutus hitsatun rakenteen väsymiskestävyyteen

Tässä työssä tutkittiin kuinka eri tavoin rakenteen mallintaminen vaikuttaa laskettuun väsy-misikään. Työssä tutkittavana rakenteena toimi Sandvik Mining and Construction OY:n las-tauskoneen nostovarsi. Nostovarrelle väsytyskokeet suoritettiin Lappeenrannan teknillisen yliopiston teräsrakenteiden laboratoriossa. Työn tavoitteena oli tutkia miten eri digitaalinen valmistuksen tasot vaikuttavat hitsatulle rakenteelle saatuun kestoikään. Työssä tutkittiin myös miten todellista geometriaa voidaan hyödyntää rakenteen kestoiän arvioinnissa. Väsytyskoejärjestely mallinnettiin FE-menetelmällä, ja järjestelystä tehtiin useita malleja käyttäen solidi- ja laattaelementtejä. Malleista laskettiin väsymisiät hot spot- ja tehollisen lovijännityksen menetelmällä, ja saatuja tuloksia vertailtiin toisiinsa ja väsytyskokeen tulok-siin. Väsytyskokeessa vaurioituneista kohdista tarkemman tutkimuksen kohteena oli nosto-varren palstalevyn kärki. Hot spot-menetelmällä saadut kestoiät vaihtelivat paikoin melko paljon eri mallien välillä. Tehollisen lovijännityksen menetelmällä saaduissa tuloksissa erot olivat pienempiä mallien välillä. FE-mallin ja venymäliuskojen jännitykset poikkesivat toisistaan paikoin melko pal-jon. Todellisen hitsatun rakenteen kestoikään vaikuttaa moni asia, ja täten FE-menetelmällä las-kettu kestoikä voi poiketa huomattavasti todellisesta kestoiästä. Varsinkin hot spot-menetel-mällä tulokset voivat poiketa hyvinkin paljon todellisuudesta, mikäli jännitystila tutkitta-vassa kohdassa on moniaksiaalinen. Todellisen geometrian mallintaminen vaatii tarkkuutta, ja alkuperäisdatan tulee olla mahdollisimman tarkkaa ja riittävän suurelta alueelta, jotta malli vastaa tarpeeksi todellista.

Lisäävän valmistuksen tarpeen kartoitus Kaakkois-Suomessa

Lisäävä valmistus (additive manufacturing, AM) on nykyaikainen menetelmä teollisuuskäyttöön tarkoitettujen kappaleiden valmistukseen. Vaikka Suomessa on vahva tieto lisäävästä valmistuksesta ja tutkimusta tehdään aktiivisesti, on menetelmän käyttö teollisuudessa vielä vähäistä. Tämän diplomityön tarkoituksena on kerätä tietoa kiinnostuksesta lisäävään valmistukseen Kaakkois-Suomen alueen yrityksiltä, jotka tekniikkaa voisivat hyödyntää. Työn tarkoituksena on myös tutkia vaatimuksia käyttöönotolle ja käyttökohteiden mahdollisuuksia Kaakkois-Suomen alueella. Työn tuloksena voidaan todeta, että kaksi syytä, jotka hidastavat lisäävän valmistuksen käyttöönottoa teollisuudessa, ovat ennakkoluulot teknologiaa kohtaan sekä perustiedon puuttuminen. Median luoma 3D-innostus luo myös paljon väärinkäsityksiä. Kaikesta huolimatta Kaakkois-Suomen alueen paperiteollisuudesta lähtenyt korkeatasoinen teollisuus- ja konepajaosaaminen pystyy toimimaan perustana teknologian käyttöönotolle.

Processamento, caracterização microestrutural e propriedades elásticas de metais celulares do sistema Ti-6Al-4V para fins de regeneração óssea

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Simplificação de malhas visando representações em multirresolução

The representation of real objects in virtual environments has applications in many areas, such as cartography, mixed reality and reverse engineering. The generation of these objects can be performed through two ways: manually, with CAD (Computer Aided Design) tools, or automatically, by means of surface reconstruction techniques. The simpler the 3D model, the easier it is to process and store it. However, this methods can generate very detailed virtual elements, that can result in some problems when processing the resulting mesh, because it has a lot of edges and polygons that have to be checked at visualization. Considering this context, it can be applied simplification algorithms to eliminate polygons from resulting mesh, without change its topology, generating a lighter mesh with less irrelevant details. The project aimed the study, implementation and comparative tests of simplification algorithms applied to meshes generated through a reconstruction pipeline based on point clouds. This work proposes the realization of the simplification step, like a complement to the pipeline developed by (ONO et al., 2012), that developed reconstruction through cloud points obtained by Microsoft Kinect, and then using Poisson algorithm

Um método para reconstrução de superfícies baseado em nuvem de pontos visando representações em multirresolução

The representation of real objects in virtual environments has applications in many areas, such as cartography, mixed reality and reverse engineering. The generation of these objects can be performed in two ways: manually, with CAD (Computer Aided Design) tools, or automatically, by means of surface reconstruction techniques. The simpler the 3D model, the easier it is to process and store it. Multiresolution reconstruction methods can generate polygonal meshes in different levels of detail and, to improve the response time of a computer program, distant objects can be represented with few details, while more detailed models are used in closer objects. This work presents a new approach to multiresolution surface reconstruction, particularly interesting to noisy and low definition data, for example, point clouds captured with Kinect sensor

Utilização de material alternativo para a obtenção e caracterização de biomodelos, por meio da técnica de impressão 3DPRINTER

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)