Cette thèse s’est déroulée dans le cadre d’une cotutelle internationale entre l’IMT - École des Mines d’Albi-Carmaux et l’Ecole Polytechnique de l’Université de Sao Paulo (EPUSP). Elle a pour but de contribuer à l’étude du comportement mécanique des alliages de titane Ti6Al4V, et plus spécialement dans le domaine du formage superplastique et du formage à chaud. L’objectif général de ce doctorat est de contribuer au développement de procédés de formages non conventionnels des alliages de titane pour applications aéronautiques. C’est pourquoi, en fonction des équipements disponibles sur les deux sites, les travaux de recherche se sont déroulés soit à l’Ecole des Mines soit à l’EPUSP. Cette thèse adresse la problématique scientifique des interactions entre le comportement mécanique dans le domaine du formage superplastique et de formage à chaud d’une part et la microstructure initiale et son évolution dans le domaine de sollicitation d’autre part. Pour cela une stratégie d’essais et de caractérisation a été développée et suivie. Les essais incluent des essais mécaniques uniaxiaux à haute température sur différents alliages Ti6Al4V présentant des microstructures initiales différentes (taille de grain 0,5; 3,0 et 4,9 μm). Une attention particulière a été portée à l’évolution microstructurale avant essai - c’est- à-dire durant sa montée en température et la stabilisation thermique de l’échantillon – et durant l’essai. Les conditions d’essai ont été choisies de façon à couvrir le domaine du formage à chaud et du formage superplastique, température de 700°C à 950°C et vitesse de déformation entre 10-1 s-1 et 10-4 s-1. La croissance de grain dépend de la microstructure initiale mais aussi de la durée de l’essai en température (croissance statique) et de la vitesse de déformation (croissance dynamique). Afin d’améliorer la validité du modèle des observations microstructurales de taille de grain sont effectués après les essais mécaniques par micrographie optique et Microscope Electronique à Balayage. Un modèle de comportement unifié a été introduit de façon à être capable de couvrir toute la plage de température et de vitesse de déformation : écrouissage cinématique non linéaire, sensibilité à la vitesse de déformation et loi de croissance de la taille des grains sont inclus dans le modèle. Afin de pouvoir valider le modèle, il a été introduit dans le code de simulation ABAQUS®. Les résultats des simulations (en particulier déformation macroscopique et taille de grain locale) ont été comparés, pour l’un des matériaux de l’étude, aux résultats d’un essai de gonflage axisymétrique de tôle. Pour obtenir un cycle de contrôle simple, les essais effectués au laboratoire de l’IPT/LEL à Sao José dos Campos au Brésil ont été opérés à vitesse de déformation constante. Les résultats montrent une très bonne corrélation avec les prédictions et permettent de conclure à une validation du modèle de comportement développé dans la thèse dans des conditions industrielles de formage de l’alliage de titane. / This thesis was developed in the frame of a Brazil-France cooperation agreement between the École des Mines d'Albi-Carmaux and the Polytechnic School of Engineering of the University of Sao Paulo (EPUSP). It aims to contribute to the study of the mechanical behaviour of Ti6Al4V alloys especially in terms of superplastic forming. The general objective of this research is to develop non-conventional forming processes for new titanium alloys applied to aerospace components. Therefore, in accordance of the equipment’s available in the two groups, the work will be conducted either at the Ecole des Mines d'Albi-Carmaux and either at EPUSP. This thesis aims to answer questions such as what are the implications in relation to the microstructural and mechanical behaviour of these alloys during superplastic and hot forming in order to establish a behaviour law for these alloys based on titanium. This requires a good knowledge of the properties of materials used in the superplastic and hot forming domain to control the parameters governing the phenomenon of superplasticity or high temperature plasticity. For this, a testing strategy and characterization methodology of those new titanium alloys was developed. The tests include high temperature uniaxial tensile tests on several Ti6Al4V alloys showing different initial grain sizes. Special focus was made on the microstructural evolution prior to testing (i.e. during specimen temperature increase and stabilization) and during testing. Testing range was chosen to cover the hot forming and superplastic deformation domain. Grain growth is depending on alloy initial microstructures but also on the duration of the test at testing temperature (static growth) and testing strain rate (dynamic growth). After testing microstructural evolutions of the alloys will be observed by optical micrograph or SEM and results are used to increase behaviour model accuracy. Advanced unified behaviour models where introduced in order to cover the whole strain rate and temperature range: kinematic hardening, strain rate sensitive and grain growth features are included in the model. In order to get validation of the behaviour model, it was introduced in ABAQUS numerical simulation code and model predictions (especially macroscopic deformation and local grain growth) were compared, for one of the material investigated, to axisymmetric inflation forming tests of sheet metal parts, also known as bulge test. To obtain a simple control cycle, tests performed at IPT/LEL laboratory in San José Dos Campos in Brazil were operated with a constant strain rate. Results show a very good correlation with predictions and allows to conclude on an accuracy of the behaviour models of the titanium alloys in industrial forming conditions.

In several applications of casting, dendritic microstructure is not desirable as it results in poor mechanical properties. Enhancing fluid flow in the mushy zone by stirring is one of the means to suppress this dendritic growth. Strong fluid flow detaches the dendrites formed at the solid-liquid interface and carries them into the mould to form slurry. When this slurry solidifies, the microstructure is characterized by globular, non-dendritic primary phase particles, separated and enclosed by a near-eutectic lower-melting secondary phase. This property represents a great potential for further processing in semisolid forming (SSF) by various techniques such as pressure die casting and forging. Among all currently available methods, linear electromagnetic (EM) stirring is considered as one of the most suitable routes for large scale production of semisolid feed stock. One of the biggest advantages of EM stirring is that the stirring intensity and direction can be modulated externally and in a non-intrusive manner. With this viewpoint, the primary objective of the present research is to investigate rheocasting using linear electromagnetic stirring. A systematic development of a linear electromagnetic stirrer (LEMS) is the subject of the first part of the thesis. The LEMS consists of a set of six primary coils displaced in space. These coils are excited by a three-phase power supply to produce an axially travelling magnetic field. The metal to be stirred is placed in the annular space of the stirrer. The travelling field induces secondary current in the molten metal. The current and magnetic fields interact to generate a net mechanical force in the metal, commonly termed as the Lorentz force. The molten metal is stirred under the influence of this force. Two prototype stirrers, one for low melting alloys and the other for aluminium alloys are developed. The stirrers are characterized by measuring forces on low melting point alloy and on solid aluminum cylinders placed inside the annular space of the stirrer. As an outcome of these tests, a non-intrusive method of detecting stirring of liquid metal is developed. The development of a rheocasting mould for the LEMS forms the second part of the work presented in the thesis. The mould design and cooling arrangement are such that solidification in the mould is primarily unidirectional. Heat from the solidifying metal is extracted at the bottom of the mould, so that the axisymmetric EM stirring effectively shears the dendrites formed at the solid-liquid interface. The outer surface of the mould is cooled with water or air exiting from 64 jets, each of 4 mm diameter. Such an arrangement provides a high heat transfer coefficient and a wide range of cooling rate in the metal ranging from 0.01 to 10 K/s. Temperature is measured at various depths in the solidifying melt and at other key locations in the mould to assess the various heat transfer mechanisms. The results from the rheocasting experiments using the above mould and LEMS are presented in the third and final part of the thesis. Such studies are required for understanding the solidification process in presence of electromagnetic stirring and for highlighting the important issues connecting solidification, fluid flow, dendrite fragmentation and the resulting microstructure. A series of experiments are performed with A356 (Al-7Si-0.3Mg) alloy. Experiments are conducted with various combinations of operating parameters, and the resulting microstructures and cooling curves at various locations are examined. The key process parameters are stirring current, cooling rate, pouring temperature, and stirring current frequency. The parametric studies also include the case without EM stirring in which liquid aluminium is poured into the rheocast mould without powering the LEMS. It is found that stirring at high currents produces non-dendritic microstructures at all locations of the billet. For lower currents, however, dendritic microstructures are observed in regions outside the zone of active stirring. Stirring also enhances heat loss from the exposed top surface, leading to solid front advancement from the top as well. Without EM stirring, microstructures are found to be dendritic everywhere. The percentage of primary α-Al phase and its number density are found to increase with stirring intensity. With a decrease in cooling rate with air as the coolant, the average grain size of primary α-Al phase increases. Excitation frequency is found to be an important parameter, with lower frequencies generating a more uniform force field distribution, and higher frequencies enhancing induction heating. At higher frequencies, the effect of higher induction heating results in the formation of larger and coarser primary phase grains. This phenomenon has led to the development of a one-step process for rheocasting and heat treatment of billets.

Sheet metal forming is used in a wide range of industrial processes ranging from tube manufacturing to automobile and aviation industry. It includes processes like stamping, bending, stretching, drawing and wheeling. In the past few years materials for sheet metal forming and, technology have improved a lot. The improved materials have higher strength and more ductility than conventional sheet steel and therefore they have to be worked differently. For such steels conventional methods can not be applied totally. So there is a need for constant improvement in technology. Trial and error method currently in use increases lead time and is not economic also. To overcome the problems, use of simulation software in metal forming processes has increased significantly. The rapid development of software technology accompanied with lower cost computer hardware have enabled many manufacturing operations to be modeled cost-effectively that only a few years ago would have been considered impractical. However there are some difficulties in simulation of sheet metal forming process. For example it is never an easy task to select the correct software for a particular process. Various authors ascribe different causes for the difficulties. Among them the prominent ones are lacunae in elasto-plastic modeling, material behaviour, involved complexities and a lack of good elements. Apart from that the demands of sheet metal processes are increasing both with respect to the tolerance requirements of the finished part and with regard to geometric complexity of the part to be formed. A few years ago finite elements have been developed using Papcovitch-Neuber solutions of the Navier equation for the displacement function. Among these elements PN5X1 has the abilities to predict both displacements and stresses accurately. And recently the element is extended to include material nonlinearity and is working well for the small deformation range. To use this element for sheet metal forming it is necessary that the element should predict correct results for large deformations. In the present work we have further extended this element for large displacements and large rotation. In the literature there are various algorithms recommended for use with large deformation. Among them we have selected a suitable algorithm and verified its usefulness. First we have taken a simple truss and applied loads to cause large deflection. We observe adequate convergence with the chosen algorithm and then we extend it to PN5X1. in large deformation analysis, equilibrium is computed about the deformed shape. In the chosen algorithm we apply incremental loading and within each load step loop we iterate for equilibrium. We ensure error free solution (equilibrium) before additional loading is introduced. With the help of flowchart these processes have been depicted. A computer program in C, based on the above incremental method and equilibrium check has been written. For the purpose of verification of the program, we have solved some benchmark tests. We start with linear cases and then attempt a number of geometric nonlinear problems like- cantilever subjected to end shear, pinched cylinder with open end etc. We have also included the classical benchmark problem of the cantilever subjected to end moment. The present algorithm gives solutions which are in excellent agreement with those reported in the literature. Finally, we look at some aspects of the problem which require further investigation.

The objective of the current study is the development of an optimization methodology for the energy efficiency of the cold roll forming process. Towards that target, a hybrid modeling approach, utilizing analytical and computational models, is proposed and developed. The energy efficiency indicator for the cold roll forming process is defined, as taking into account the cold roll forming process as a system with energy inputs and outputs. An analytical model was proposed and analyzed for the calculation of such energy efficiency indicator. Internal deformation work for longitudinal and bending strains and pulling frictional work were taking into account. Validation of the analytical model with experimental data and a sensitivity analysis for cold roll forming process variables are then presented. Furthermore a computational model for the cold roll forming process was proposed and analyzed. Simulation methods and modeling approach are analyzed for both forming and springback analysis. The computational model sections and variables are analyzed and results for longitudinal strains are validated with experimental data. The aforementioned modeling approaches were integrated within an optimization methodology, which consist of a robust design algorithm and a closed loop checking for quality constraints. A robust design algorithm implementation was proposed utilizing the analytical model, as taking into account the uncertainty of noise factors within computer experiments. Closed loop checking of quality constraints is implemented using computational model and specified process guidelines. The main outcome of this work is the complete method that was proposed and realized through analytical and computational models. The evaluation of the case study revealed the efficiency and practicality of the suggested approach towards energy efficiency optimization of the cold roll forming process. / Το αντικείμενο αυτής της διατριβής είναι η ανάπτυξη μιας μεθοδολογίας βελτιστοποίησης της ενεργειακής αποδοτικότητας της διεργασίας διαμόρφωσης με περιστρεφόμενους κυλίνδρους. Προς αυτόν τον στόχο, μια υβριδική προσέγγιση μοντελοποίησης, χρησιμοποιώντας αναλυτικό και υπολογιστικό μοντέλο, προτείνεται και αναπτύσσεται. Ο δείκτης ενεργειακής αποδοτικότητας για την διεργασία διαμόρφωσης με περιστρεφόμενους κυλίνδρους ορίζεται, λαμβάνοντας υπόψη τη διεργασία ως ένα σύστημα με ενεργειακές εισροές και εκροές. Ένα αναλυτικό μοντέλο προτείνεται και αναλύεται για τον υπολογισμό του δείκτη ενεργειακής αποδοτικότητας. Υπολογίζονται το εσωτερικό έργο παραμόρφωσης για διαμήκεις και κάμψης παραμορφώσεις, και έργο τριβής μέσω έλξης του υλικού. Το αναλυτικό μοντέλο επαληθεύεται με πειραματικές παρατηρήσεις και στην συνέχεια πραγματοποιείται μία ανάλυση ευαισθησίας για της μεταβλητές της διεργασίας διαμόρφωσης με περιστρεφόμενους κυλίνδρους. Επιπροσθέτως, ένα υπολογιστικό μοντέλο για την διεργασία διαμόρφωσης με περιστρεφόμενους κυλίνδρους προτείνεται και αναλύεται. Οι μέθοδοι προσομοίωσης και η προσέγγιση μοντελοποίησης αναλύονται για τις αναλύσεις διαμόρφωσης και επαναφοράς. Τα τμήματα του υπολογιστικού μοντέλου και οι μεταβλητές του αναλύονται καθώς και τα αποτελέσματα για τις διαμήκεις παραμορφώσεις επαληθεύονται με πειραματικά δεδομένα. Οι εν λόγω προσεγγίσεις μοντελοποίησης ενσωματώνονται σε μία μεθοδολογία βελτιστοποίησης, η οποία αποτελείται από έναν αλγόριθμο εύρωστου σχεδιασμού και έναν κλειστό βρόγχο για τον έλεγχο των ποιοτικών περιορισμών. Η υλοποίηση του αλγόριθμου εύρωστου σχεδιασμού προτείνεται με χρήση του αναλυτικού μοντέλου, παίρνοντας υπόψη την αβεβαιότητα των μεταβλητών θορύβου σε πειράματα με Η/Υ. Ο κλειστός βρόγχος για τον έλεγχο των ποιοτικών περιορισμών χρησιμοποιεί το υπολογιστικό μοντέλο και συγκεκριμένες οδηγίες διεργασίας. Το κύριο αποτέλεσμα αυτής της εργασίας είναι η πλήρης μεθοδολογία που προτείνεται και πραγματοποιείται μέσω αναλυτικού και υπολογιστικού μοντέλων. Η αξιολόγηση της εφαρμογής της μεθοδολογίας σε βιομηχανικό προϊόν αποκάλυψε την αποτελεσματικότητα και την πρακτικότητα της προτεινόμενης προσέγγισης για την βελτιστοποίηση της ενεργειακής αποδοτικότητας της διεργασίας διαμόρφωσης με περιστρεφόμενους κυλίνδρους.

This thesis project is the final part of the Master of Science degree in Industrial Design Engineering with specialisation in Production Design at Luleå University of Technology. The project was conducted at Scania Ferruform in Luleå through January to June of 2018. Ferruform currently produces the side members to Scania’s trucks in a traditional roll forming machine. The technology of roll forming has developed and today there is a new version of the technology called 3D roll forming, which allows for forming beams with variable cross sections. Forming side members with variable web dimensions would make it possible to produce side members that have optimised form, which allows for a weight reduction in the trucks and an increase in the customers payload. The objective of this project was to identify the benefits and the limitations of investing in 3D roll forming at Ferruform’s side member production and to investigate how the technology should be implemented. The study had two aims. The first aim was to present a proposal for the implementation of 3D roll forming in the side member production at Ferruform. The second aim was to design a project plan for Ferruform’s eventual further work of implementing 3D roll forming. A literature study was performed and resulted in a theoretical framework consisting of relevant theories regarding industrial design engineering, roll forming, organisational changes and sustainability. A description and analysis of the current state was made and included the side member production, the side member paint shop and the chassis line at Scania Södertälje. The current state was mainly described through conducting interviews and performing observations. Process flow analysis was then done to visualise and analyse the current state. The next step was to describe and analyse the future state, this was done taking advantage of the available knowledge at Ferruform and analysing the material from a benchmark performed before this thesis project started. The description and analysis of the current and future state resulted in a specification of requirements. Four concepts for the future side member production were designed and evaluated with a Pugh matrix. The evaluation resulted in choosing one of the concepts for further development. The final concept for the implementation consists of keeping the traditional roll forming machine and building a new production line for 3D roll forming. The 3D roll forming machine consists of a one-part machine which requires the side members to pass through the machine twice. The results of the thesis showed that the amount of side members that would enable profit by being produced with 3D roll forming, was lower than expected. The results of the thesis also show that there are many considerations and further investigations that need to be conducted before starting an implementation could be started. However, as relevant theories propose, it is concluded that 3D roll forming is a flexible production method which would make it possible for Scania to satisfy individual customer needs and also provide the company with a long-term solution for future customer needs. / Det här examensarbetet är den sista delen för en civilingenjörsexamen inom Teknisk design med inriktning mot Produktionsdesign vid Luleå tekniska universitet. Projektet utfördes på Scania Ferruform i Luleå under januari till juni 2018. Ferruform producerar sidobalkar till Scanias lastbilar i en traditionell rullformningsmaskin. Rullformningstekniken har dock utvecklats och idag finns det en ny version av tekniken som kallas 3D-rullformning och som möjliggör formning av balkar med variabla tvärsnitt. Genom att forma sidobalkar med variabla livbredder skulle det vara möjligt att producera balkar med optimerad form, vilket innebär en viktminskning av lastbilarna och en ökning i kundernas nyttolast. Syftet med projektet var att identifiera fördelar och nackdelar med att investera i 3D-rullformning i Ferruforms sidobalkstillverkning och undersöka hur tekniken borde implementeras. Studien hade två olika mål. Det första målet var att presentera ett förslag för implementeringen av 3D-rullformning i sidobalktillverkningen på Ferruform. Det andra var att ta fram en projektplan för Ferruforms eventuella fortsatta arbete med att implementera 3D-rullformning. En litteraturstudie utfördes för att ta fram en teoretisk referensram bestående av relevanta teorier inom teknisk design, rullformning, organisationsförändringar och hållbarhet. En beskrivning och analys av nuläget genomfördes och inkluderade sidobalkstillverkningen, sidobalksmåleriet och chassimonteringen på Scania Södertälje. Nuläget undersöktes främst genom intervjuer och observationer. Processflödesanalys användes för att visualisera och analysera nuläget. Nästa steg i projektet var att beskriva och analysera det framtida läget, detta gjordes genom att ta tillvara på den tillgängliga kunskapen hos personalen på Ferruform och genom att analysera det benchmarkingbesök som gjordes innan detta projekt påbörjades. Undersökningarna av nuläge och framtid resulterade i kravspecifikation. Fyra koncept för den framtida sidobalkstillverkningen togs fram och utvärderades med hjälp av metoden Pughs matris. Utvärderingen resulterade i att ett koncept valdes ut för att utvecklas ytterligare. Det slutliga konceptet för implementeringen består av den nuvarande, traditionella rullformningsmaskinen och uppbyggnaden av en ny produktionslina för 3D-rullformning. 3D-rullformningsmaskinen består av en maskindel, vilket kräver att sidobalkarna går igenom maskinen två gånger. Projektets resultat visade att mängden sidobalkar som skulle möjliggöra vinst genom att tillverkas med 3D-rullformning, var lägre än väntat. Resultaten visar också att det är många överväganden och vidare utredningar som krävs innan en implementering kan påbörjas. Dock har jag, precis som relevant teori föreslår, också dragit slutsatsen att 3D-rullformning är en flexibel produktionsmetod som skulle göra det möjligt för Scania att tillfredsställa individuella kundbehov och även förse företaget med en långsiktig lösning för framtida kundbehov.

Entre os processos de fabricação mecânicos atuais destacam-se os processos de conformação de chapas metálicas devido à sua produtividade e confiabilidade e a seus baixos custos de produção, baixo consumo de material e produtos nos formatos bem próximos dos esperados nas fases de projeto. Isto só é possível se todas as variáveis do projeto e do processo estiverem conforme as especificações prévias, exigidas principalmente em setores da indústria tais como o aeronáutico e o automobilístico. Um recurso útil para se alcançar estas expectativas é o estudo da estricção e da conformabilidade em chapas metálicas, representadas em diagramas de limite de conformação (DLC), os quais, aliados à análise numérica através do Método dos Elementos Finitos, permitem predições a respeito das variáveis de projeto. Este trabalho tem como objetivos rever e aplicar conceitos relativos a estes aspectos. O objetivo principal deste trabalho é de dispor uma metodologia de avaliação e otimização para o processo de estampagem, utilizando-se elementos finitos e DLC. Uma modificação no método de Marciniak-Kuczynski é utilizada para a obtenção do DLC. Busca-se com isto uma contribuição para a redução de custos em aplicações industriais com o uso desta metodologia através da diminuição das fases de tentativas e erros em projeto e reforma de estampos (try-outs). / Nowadays, sheet metal forming processes have an important role amongst the mechanical manufacturing processes, because they are characterized by high productivity and reliability at low cost, low material waste and near net shapes from design. This is achieved by controlling the design and process parameters according to initial constraints. This scenario is common at aeronautic and at automobilistic productions . These results are obtained by studies of necking and formability in sheet metals and by the use of forming limit diagrams (FLD) and finite element numerical analysis to predict design parameters. This work reviews these concepts and presents a methodology for optimization of deep drawing processes, by using finite element method and FLD. A modification of the Marciniak-Kuczynski method has been introduced to obtain the FLD. Once this methodology has been performed, it can be possible to reduce try-outs in sheet metal dies and costs reduction can also be obtained.

Esta dissertação tem como objetivo modelar numericamente a manufatura de painéis aeronáuticos de ligas AA7XXX com dupla curvatura variáveis sem reforçadores por meio do processo de conformação por fluência com envelhecimento (CFE). A fundamentação dos fenômenos processo CFE foram estudadas com ensaios de tração à quente, fluência e microscopia eletrônica de transmissão (MET) em amostras de AA7050. Utilizou-se a liga AA7010 e ensaios de fluência da literatura para a aplicação de modelos uniaxiais tanto simplificados quanto unificados para predição do comportamento de fluência com envelhecimento. Um modelo uniaxial unificado foi implementado programa de método dos elementos finitos MSC.Marc por meio de uma sub-rotina codificada em FORTRAN. Em seguida, construiu-se uma metodologia para se simular a fabricação de um revestimento feito de AA7475. Comparou-se a geometria obtida com a de um experimento real. Os resultados da modelagem uniaxial mostram que o modelo obtido é 46% mais exato que o modelo da literatura utilizado como referência e podem ser melhorados caso a influência do envelhecimento na fluência seja mais adequadamente quantificado. O método de simulação do processo CFE se mostrou aderente ao comportamento do material e pode ser mais exato conforme se melhore a modelagem do material. / This dissertation aims to model numerically the manufacture of aircraft wing panels with double variable curvature and without stringers by creep age forming (CAF) process. The phenomena fundamentals were studied using AA7050 alloy samples through hot tensile, creep tests and transmission electron microscopy (TEM).The modeling of creep behavior under uniaxial and aging condition was performed using both simplified and unified models and compared with literature data for the alloy AA7010. A unified model was implemented in MSC.Marc finite elements method program through a subroutine coded in FORTRAN. Then, it was built a methodology to simulate an AA7475 panel forming. The obtained geometry was compared with a real experiment. The uniaxial modeling results show that the obtained simplified model is 46% more exact that the literature model, utilized as reference. These results can be improved if the ageing influence on creep is better quantified. The simulation method has described the material behavior, but there are limitations due to the power law material model.

A redução do ruído externo gerado por aeronaves operando nas proximidades de grandes centros urbanos é apontada como uma questão vital para a manutenção e expansão sustentável das atividades da aviação civil. Nas últimas décadas, reduções significativas no ruído gerado pelos sistemas de propulsão da aeronave tornaram relevantes as contribuições do trem de pouso e dos dispositivos de hiper-sustentação (flapes e eslates) para o ruído global da aeronave. A caracterização do espectro acústico de cada componente hiper-sustentador é necessária para o desenvolvimento de métodos preditivos de ruído e projetos aerodinâmicos que viabilizem a redução de ruído sem penalizações severas para o desempenho e a segurança da aeronave. Experimentos com modelos em escalas mostram que a contribuição de cada elemento hiper-sustentador para o ruído global é determinada pelo tamanho e modelo da aeronave. Tal fato dificulta a generalização dos resultados experimentais e determina a caracterização do espectro acústico de cada componente de um aerofólio em termos de sua geometria e configuração operacional. Este trabalho tem como objetivo principal a caracterização do ruído do eslate a partir de medições experimentais com um aerofólio hiper-sustentador McDonnell Douglas (30P30N), composto por flape, eslate e elemento principal. Os experimentos foram realizados em túnel de vento de seção fechada, e as medições acústicas contaram com o uso de uma antena composta por 62 microfones. Os dados acústicos foram processados com algoritmos de beam-forming convencional e deconvolução DAMAS (Deconvolution Approach for the Mapping of Acoustic Sources). A aplicação de técnicas de beam-forming permite representar uma distribuição espacial de fontes na forma de um mapa acústico e determinar o nível de ruído gerado por fontes que concorrem de forma independente para o ruído global. A base de dados experimentais permite o estudo do ruído do eslate sob diferentes configurações operacionais e geométricas do aerofólio. A análise do espectro acústico do eslate revela a ocorrência de ruído tonal em baixa e alta frequências, e ruído de banda larga em média frequência. Os mapas de beam-forming obtidos associam o ruído de banda larga com uma distribuição bidimensional de fontes ao longo da envergadura do eslate. O ruído do eslate aumenta com a velocidade de escoamento livre, enquanto que os picos tonais de baixa frequência e o ruído de banda larga decrescem com o aumento do ângulo de ataque do aerofólio de 2° para 10°. Os espectros de ruído do eslate colapsam quando reescalados pelo número de Mach do escoamento livre elevado a uma potência entre 4 e 5, e o ruído tonal colapsa em Strouhal dado pela corda do eslate e pela velocidade do escoamento base. Os resultados mostram que o ruído do eslate é fortemente dependente da geometria do aerofólio, particularmente para variações de overlap. Uma boa correspondência quantitativa foi obtida comparando-se espectros experimentais de ruído do eslate com espectros numéricos, obtidos a partir de um modelo com a mesma geometria e em condições de teste idênticas, o que indica a viabilidade do uso de túneis de vento de secção fechada para a realização de experimentos aeroacústicos. / The reduction in the noise produced by aircraft operating in the vicinity of large urban centers is an important issue for a sustainable growth in the civil aviation activities. Over the last decades, from a signicant reduction achieved in the noise generated by aircraft propulsion systems, the contribution of both landing gears and high-lift devices (flaps and slats) has become important to the aircraft overall noise. The identication of the noise signature of each high-lift component is required for the development of both noise prediction methods and new aerodynamic design concepts toward achieving a noise reduction without severe penalty over the aircraft performance and safety. Scaled model experiments have shown that the importance of each airframe component to the overall noise is determined by particularities in both aircraft geometry and size. Such noise model dependence hampers the generalization of experimental results from a reference testing model and leads to the necessity of assessing noise generation according to the testing model geometry and operational condition. This study focuses mainly on the characterization of slat noise from experimental measurements on a high-lift Mcdonnell Douglas (30P30N) airfoil, composed of a slat, a ap and a main element. Measurements were performed in a closed-section wind tunnel by a 62-microphone array and the acoustic data were processed with in-house codes based on conventional beam-forming and DAMAS (Deconvolution Approach for theMapping of Acoustic Sources) algorithms. Beam-forming techniques potentially enable the representation of a spatial source distribution as an acoustic map, from which the contribution of independent sources to the overall noise can be estimated. The experimental database enables the study of the slat noise from dierent airfoil operational conditions and geometrical settings. The slat noise spectral signature reveals the occurrence of tonal noise over both low- and high-frequency bands and also broadband noise over a mid-frequency range. Beam-forming maps indicate the slat broad-band noise originates from a source spatially distributed along the slat span. The slat noise increases in function of the ow speed, whereas low-frequency tonal peaks and the broadband noise decrease as the airfoil angle of attack increases from 2 to 10. The slat noise spectra scalle when the Mach number is raised to a power between 4 and 5, and the tonal noise collapses with Strouhal based on the slat chord and the ow speed. Results show the slat noise is strongly in uenced by the airfoil geometry, particularly for variations in the overlap. A good quantitative agreement was achieved through the comparison between the experimental and numerical slat noise spectra for the same model geometry and test conditions, which indicates the viability of performing aeroacoustic experiments in closed-section wind tunnels.

The doctoral thesis deals with utilization of hydroforming technology for manufacturing of a new type of solar absorber, which has directly flow meandering structure and a structured surface consisting of pyramidal elements. Austenitic stainless steel X5CrNi18-10 is used as a material for absorbers production. At the beginning of the thesis, a literary research is performed, which is focused on particular methods of hydroforming technology, their applicability for this problem, forming limits determination and usability of numerical simulation. Based on the literature study, the production technology was developed by using parallel hydroforming technology and it was optimized by using a numerical simulation in the ANSYS software. Hydroforming parameters for two variants of the structured surface with pyramidal cavities with apex angle of 90° and 60° were determined from the calculations and the material tests.

Die Bauteileigenschaften von Bauteilen und Baugruppen im Karosseriebau werden maßgeblich durch die während des Tiefziehprozesses auftretenden Formänderungen und Verfestigungen beeinflusst. In der vorliegenden Arbeit wird daher die Umformsimulation in eine repräsentative virtuelle Prozesskette des Karosseriebaus integriert. Dazu wird zunächst die Datenübertragung zwischen den einzelnen Simulationsprogrammen in der Prozesskette Umformen - Fügen - Crash realisiert. Mit der anschließend durchgeführten Sensitivitätsanalyse wird festgestellt, welche Größen einen signifikanten Einfluss auf die Folgesimulationen haben. Aufbauend auf den Ergebnissen der Sensitivitätsanalyse wird eine Methode zur Gestaltung von einfachen Ankonstruktionen zur Verbesserung der Qualität der Ergebnisse der inversen Umformsimulation entwickelt und an einem Bauteil aus dem Karosseriebau validiert. Mit den durch die einfache Ankonstruktion erzielten Verbesserungen in den Ergebnissen der inversen Umformsimulation kann die entwickelte Methode einen Beitrag zur Erhöhung der Qualität der nachfolgenden Prozesssimulationen in der Prozesskette leisten.