Sheet metal forming is one of the most common forming processes used in the industry, especially in the automotive industry. It becomes a common sense, that by increasing the accurate simulation of sheet metal forming, the industry can save dramatic cost in trial-and-error process when designing the sheet metal forming tools. In past decades, considerable studies have been done in the field of numerical analysis of metal forming processes, particularly in springback prediction. Significant progresses have been made, but the accuracy of simulation results still needs to improve. One reason is that, in the typical sheet metal forming analysis the tools are considered as absolute un-deformable rigid bodies. The deformation of the tools, which happens in the real production, is not taken into account. Another reason may be that the classic simulation considers the friction coefficient between the tools and blank as constant. However, the actual friction condition depends on a number of parameters. The objective of this thesis work is trying to investigate how it will affect the springback prediction results when either the tool deformation or more complex friction conditions are considered. The purpose is nothing related with the precise simulation about the true problem or how accuracy the simulation results show compared to the experiment results. The work is only to give an emphasis hint that how the FE-model and friction mode chosen affects the springback results when doing a numerical analysis. A simple model called flex rail is used for sheet metal forming simulations with three different friction models. A comparison between the results clearly shows a difference when advanced friction models are applied. A 3D elastic solid model is created to compare the result with rigid model. The results show the difference when deformation of the tools is taken into account. Finally, an actual case with tools from the industry is investigated. The tools are from SAAB Cars Body Components. This case is to investigate the possibility and necessity of applying the advanced friction model and elastic tools when a complex real industry problem is faced. Further study is needed to do with comparison experimental data to verify the accuracy when these models are used.

Sheet metal forming has an important place among metal forming processes. As the usage of sheet metal increases, the fatigue simulation and optimization of these parts become more important. This thesis study examines the change of the fatigue life of a sheet metal part after forming. A sphere-like shape is deep drawn and change in thickness and residual stresses are analyzed. To understand the effect of residual stresses, deep drawn parts with and without residual stress tested against the fatigue failure. In parallel, the forming process is simulated with an implicit finite element method (FEM). The success of forming simulation is discussed in the study. Thickness changes and residual stresses calculated with FEM are included in computer aided fatigue analysis. The effect of thickness changes is examined with the results of FEM analysis. The effectiveness of the whole simulation process is discussed by comparing the outputs of experiments and computational analysis.

The aim of this thesis is to investigate the effects of bulging and deep drawing processes on St4 cold rolled steel by simulation and experimental characterization. In the simulations, commercial software programs MSC Marc and Simufact.forming were used. The experimental studies cover metallographic investigations, hardness measurements, and residual stress measurements. Residual stress measurements were carried out by different non- destructive characterization methods / X-ray diffraction and Magnetic Barkhausen Noise. The experimental and simulation results were correlated with each other.

Abstract Today sheet metal forming is used to make a variety of mass production because it has a high production rate. One of the biggest concerns in sheet metal forming is wear of the tool in form of galling. Galling in sheet metal forming is characterised by an increased tool surface roughness, unstable friction in the forming process and undesirable scratches on the final products. Several ways of ranking materials resistance to galling exist today but only ASM G98 is standardised. Nevertheless, some different methods developed for ranking tool materials’ tendency to galling have also been developed. The aim of this thesis is to develop and improve the Uddeholm Tooling Tribo Test rig located at Uddeholm Tooling AB. The rig, which is a variation of cylinder-on-cylinder test equipment, was improved with a new tool holder, a utilization of the real sheet material counter face and a new data acquisition system and software. The galling was detected using scratches on the sheet, metallographic analysis of the material adhered on the tool specimen, monitoring of coefficient of friction and the standard deviation of the coefficient of friction. The obtained results show difficulties with ranking of tool materials in terms of galling resistance under non-lubricated conditions. The tool steels tested were SVERKER21 and UNIMAX. AISI304-10, DC04 and DOCOL1000DP sheets were used. Additionally a low friction coating of BalinitC on SVERKER21 was also included. All specimens of the tool steels showed signs of galling on every run, only the low friction coating showed a transition in behaviour of friction coefficient corresponding to galling initiation. The standard deviation of the coefficient of friction increased at low loads. A decrease of the test loads led to stability loss of the system detected by an increase in the standard deviation of the coefficient of friction. This might happen because the Kistler platform is originally designed for larger loads. Although, the test rig does not work properly in its present state, the concept looks promising.

Os Aços Avançados de Alta Resistência ou AHSS (do inglês Advanced High Strength Steels) apresentam muitas vantagens mecânicas em relação aos aços convencionais. Seu uso crescente na indústria automotiva deve-se principalmente à sua capacidade de possibilitar a redução de peso e, ao mesmo tempo, o aumento da segurança aos ocupantes do veículo em caso de colisões. No entanto, apresentam maiores dificuldades no que se refere à conformabilidade (maiores níveis de solicitação e desgaste das ferramentas, menor deformabilidade plástica, etc). Assim, alguns testes para avaliar a conformabilidade destes materiais ganham maior importância. É o caso do Teste de Expansão de Furos, cuja propriedade medida é a Razão de Expansão de Furos (REF). Neste trabalho investiga-se o processo de expansão de furos para o aço avançado de alta resistência (AHSS) martensítico DOCOL 190M, sob as seguintes condições de processo: duas formas de obtenção do furo (jato d’água e usinagem); duas geometrias distintas de punções (cônico de 60º e elíptico); diversos diâmetros do furo inicial; com e sem o uso de lubrificante; com acabamento diferenciado da borda do furo; e expansão com deslocamento do punção em etapas. Os experimentos demonstram que a expansão de furos possui uma estreita relação com a geometria do punção utilizado para a expansão, bem como com o diâmetro do furo inicial, acabamento da borda e condições de lubrificação. A partir dos resultados experimentais de expansão de furos foi possível realizar a calibração de um software de simulação computacional em relação ao dano crítico do material no momento da fatura na borda do furo. / Advanced High Strength Steels (AHSS) offer many mechanical advantages over conventional steels. Its increasing use in the automotive industry is mainly due to its ability to reduce weight and, at the same time, increase occupant safety in the event of collisions. However, they present greater difficulties with respect to the formability (higher levels of solicitation and wear of the tools, lower plastic formability, etc). Thus, some tests to evaluate the formability of these materials come to have greater importance. This is the case of the Hole Expansion Test, whose measured property is the Hole Expansion Ratio (REF). This work investigates the hole expansion process for a martensitic advanced high-strength steel (AHSS), DOCOL 190M, under the following process conditions: two ways of obtaining the hole (water jet and machining); two different geometries of punctures (conical of 60º and elliptical); various diameters of the initial hole; with and without the use of lubricant; with differentiated finishing of the hole edge; and expansion with punch displacement in steps. The experiments demonstrate that the hole expansion has a close relationship with the geometry of the punch used for the expansion, as well as the initial hole diameter, edge finish and lubrication conditions. From the experimental hole expansion results it was possible to carry out the calibration of a computational simulation software in relation to the critical damage of the material at the moment of hole edge rupture.

Este trabalho apresenta um estudo sobre o processo de Estampagem Incremental de Chapas, em Latão C-268 de diferentes espessuras (s0: 0.50, 0.70 e 1.00 mm), motivado pela inobservância de pesquisas desta matéria prima neste processo de conformação de chapas. Atualmente, este material tem grande aplicação na confecção de utensílios domésticos (baixelas, travessas, etc) e ferragens para construção civil (espelhos, cubas, etc), instrumentos musicais de sopro e núcleos de radiadores automotivos, tendo assim, um amplo campo de aplicação industrial, e potencial para as aplicações do processo de Estampagem Incremental de Chapas. A pesquisa está pautada na caracterização das matérias primas, para a obtenção de dados como as Curvas de Escoamento, Índices de Anisotropia (r), Curvas Limite de Conformação (CLC) e em experimentos de Estampagem Incremental de Chapas, realizados em uma máquina dedicada a este processo de conformação. Para a realização dos experimentos, foram utilizados Incrementos Verticais com diferentes valores (∆Z: 0.10, 0.50 e 1.00 mm), assim como duas ferramentas de estampagem (DT: Ø10 e Ø15 mm). Foram aplicadas duas formas geométricas diferentes: Tronco de Cone e Tronco de Pirâmide, ambos com perfil radial das paredes verticais. Ao todo, foram realizados 15 experimentos diferentes na modalidade SPIF. Os experimentos foram realizados em uma máquina dedicada ao processo, capaz da aquisição dos valores de Força (FX, FY e FZ) durante a realização dos testes. Com a realização dos experimentos SPIF, foi possível a elaboração da Linha Limite de Fratura – LFC da chapa latão C-268 nas três espessuras investigadas, onde os resultados apontam para valores maiores de deformação verdadeira (1 vs 2), quando comparados aos valores da CLC. Adicionalmente, a LFC das três espessuras de chapas analisadas, apontam os valores das maiores deformações verdadeiras (1) muito próximos, evidenciando neste caso que a diminuição do Incremento Vertical (∆Z) é mais relevante para a estampagem do que o aumento da espessura da chapa. As geometrias Tronco de Cone e Tronco de Pirâmide apresentaram discrepâncias geométricas toleráveis em relação ao perfil projetado, mas diferentes entre si, influenciados pelo retorno elástico diferente de cada geometria. Entretanto, suas fraturas apresentaram o mesmo comportamento, propagação no sentido meridional. Os experimentos SPIF realizados com a ferramenta de estampagem com Ø10mm proporcionaram as maiores profundidades. A medição da espessura final (s1) próximas as regiões fraturadas, comprovou os valores medidos não ultrapassaram os respectivos valores resultantes da expressão matemática Lei do Seno, e ainda, que quanto menor a espessura inicial (s0) da chapa, menor a variação dos valores medidos e calculados. A análise das Forças (FX, FY e FZ) resultantes do processo SPIF mostram que quanto maior o Incremento Vertical (∆Z), maior a espessura inicial (s0) da chapa, e maior do diâmetro (DT) da ferramenta de estampagem, maiores serão as Forças necessárias no SPIF. Adicionalmente, foi possível determinar os valores de Atrito (µ), obtidos em função das Forças (FX, FY e FZ) do processo SPIF. / This paper presents a study of the Incremental Sheet Forming process, in Brass C-268 of different thicknesses (s0: 0.50, 0.70 and 1.00 mm), motivated by non-observance of research of this raw material in this sheet forming process. Currently, this material has great application in the manufacture of household items (plates, platters, etc.) and hardware for building (locks, vats, etc.), wind musical instruments and automotive radiator cores, having thus, a large industrial application field, and potential for the applications of the Incremental Sheet Forming process. The research is based on the characterization of raw materials, to obtain data such as Flow Curves, Anisotropy Indices (r), Forming Limit Curve and in Incremental Sheet Forming experiments, performed on a machine dedicated to this forming process. For the realization of the experiments, Vertical Increments with different values were used (∆Z: 0.10, 0.50 e 1.00 mm), As well as two forming tools (DT: Ø10 e Ø15 mm). Two different geometric forms were applied: Cone Frustum and Pyramid Frustum, both with radial profile of vertical walls. In all, 15 different SPIF experiments were performed. The experiments were carried out in a machine dedicated to the process, able to acquire the values of Force (FX, FY e FZ) during the tests. With the realization of SPIF experiments, it was possible to elaborate the Fracture Forming Line – FFL of Brass C-268 sheet, In the three thicknesses investigated, Where the results indicate higher values of true strain (1 vs 2), when compared to the FLC values. Additionally, the FFL of the three sheet thicknesses analyzed, indicate the values of the highest true deformations (1) very close, evidencing in this case, that the decrease of Vertical Increment (∆Z) is more relevant for the forming than the increase in sheet thickness. The Cone Frustum and Pyramid Frustum geometries presented tolerable geometric discrepancies in relation to the projected profile, more different from each other, influenced by different springback of each geometry. However, their fractures presented the same behavior, meridional direction propagation. The SPIF experiments performed with the forming tool with Ø10mm provided the greatest depths. The final thickness (s1) measurement near the fractured regions, proved the measured values did not exceed the respective values resulting from the mathematical expression Sine Law, and also, that the lower the initial thickness (s0) of sheet, lower the variation of the measured and calculated values. Analysis of Forces (FX, FY e FZ) resulting from the SPIF process, show that the larger the Vertical Increment (∆Z), larger the initial thickness (s0) of the sheet, and larger diameter (DT) of the forming tool, larger will be the necessary forces in SPIF. In addition, it was possible to determine the values of Friction (µ), obtained in function of the SPIF Forces (FX, FY e FZ).

Os Aços Avançados de Alta Resistência ou AHSS (do inglês Advanced High Strength Steels) apresentam muitas vantagens mecânicas em relação aos aços convencionais. Seu uso crescente na indústria automotiva deve-se principalmente à sua capacidade de possibilitar a redução de peso e, ao mesmo tempo, o aumento da segurança aos ocupantes do veículo em caso de colisões. No entanto, apresentam maiores dificuldades no que se refere à conformabilidade (maiores níveis de solicitação e desgaste das ferramentas, menor deformabilidade plástica, etc). Assim, alguns testes para avaliar a conformabilidade destes materiais ganham maior importância. É o caso do Teste de Expansão de Furos, cuja propriedade medida é a Razão de Expansão de Furos (REF). Neste trabalho investiga-se o processo de expansão de furos para o aço avançado de alta resistência (AHSS) martensítico DOCOL 190M, sob as seguintes condições de processo: duas formas de obtenção do furo (jato d’água e usinagem); duas geometrias distintas de punções (cônico de 60º e elíptico); diversos diâmetros do furo inicial; com e sem o uso de lubrificante; com acabamento diferenciado da borda do furo; e expansão com deslocamento do punção em etapas. Os experimentos demonstram que a expansão de furos possui uma estreita relação com a geometria do punção utilizado para a expansão, bem como com o diâmetro do furo inicial, acabamento da borda e condições de lubrificação. A partir dos resultados experimentais de expansão de furos foi possível realizar a calibração de um software de simulação computacional em relação ao dano crítico do material no momento da fatura na borda do furo. / Advanced High Strength Steels (AHSS) offer many mechanical advantages over conventional steels. Its increasing use in the automotive industry is mainly due to its ability to reduce weight and, at the same time, increase occupant safety in the event of collisions. However, they present greater difficulties with respect to the formability (higher levels of solicitation and wear of the tools, lower plastic formability, etc). Thus, some tests to evaluate the formability of these materials come to have greater importance. This is the case of the Hole Expansion Test, whose measured property is the Hole Expansion Ratio (REF). This work investigates the hole expansion process for a martensitic advanced high-strength steel (AHSS), DOCOL 190M, under the following process conditions: two ways of obtaining the hole (water jet and machining); two different geometries of punctures (conical of 60º and elliptical); various diameters of the initial hole; with and without the use of lubricant; with differentiated finishing of the hole edge; and expansion with punch displacement in steps. The experiments demonstrate that the hole expansion has a close relationship with the geometry of the punch used for the expansion, as well as the initial hole diameter, edge finish and lubrication conditions. From the experimental hole expansion results it was possible to carry out the calibration of a computational simulation software in relation to the critical damage of the material at the moment of hole edge rupture.

Este trabalho apresenta um estudo sobre o processo de Estampagem Incremental de Chapas, em Latão C-268 de diferentes espessuras (s0: 0.50, 0.70 e 1.00 mm), motivado pela inobservância de pesquisas desta matéria prima neste processo de conformação de chapas. Atualmente, este material tem grande aplicação na confecção de utensílios domésticos (baixelas, travessas, etc) e ferragens para construção civil (espelhos, cubas, etc), instrumentos musicais de sopro e núcleos de radiadores automotivos, tendo assim, um amplo campo de aplicação industrial, e potencial para as aplicações do processo de Estampagem Incremental de Chapas. A pesquisa está pautada na caracterização das matérias primas, para a obtenção de dados como as Curvas de Escoamento, Índices de Anisotropia (r), Curvas Limite de Conformação (CLC) e em experimentos de Estampagem Incremental de Chapas, realizados em uma máquina dedicada a este processo de conformação. Para a realização dos experimentos, foram utilizados Incrementos Verticais com diferentes valores (∆Z: 0.10, 0.50 e 1.00 mm), assim como duas ferramentas de estampagem (DT: Ø10 e Ø15 mm). Foram aplicadas duas formas geométricas diferentes: Tronco de Cone e Tronco de Pirâmide, ambos com perfil radial das paredes verticais. Ao todo, foram realizados 15 experimentos diferentes na modalidade SPIF. Os experimentos foram realizados em uma máquina dedicada ao processo, capaz da aquisição dos valores de Força (FX, FY e FZ) durante a realização dos testes. Com a realização dos experimentos SPIF, foi possível a elaboração da Linha Limite de Fratura – LFC da chapa latão C-268 nas três espessuras investigadas, onde os resultados apontam para valores maiores de deformação verdadeira (1 vs 2), quando comparados aos valores da CLC. Adicionalmente, a LFC das três espessuras de chapas analisadas, apontam os valores das maiores deformações verdadeiras (1) muito próximos, evidenciando neste caso que a diminuição do Incremento Vertical (∆Z) é mais relevante para a estampagem do que o aumento da espessura da chapa. As geometrias Tronco de Cone e Tronco de Pirâmide apresentaram discrepâncias geométricas toleráveis em relação ao perfil projetado, mas diferentes entre si, influenciados pelo retorno elástico diferente de cada geometria. Entretanto, suas fraturas apresentaram o mesmo comportamento, propagação no sentido meridional. Os experimentos SPIF realizados com a ferramenta de estampagem com Ø10mm proporcionaram as maiores profundidades. A medição da espessura final (s1) próximas as regiões fraturadas, comprovou os valores medidos não ultrapassaram os respectivos valores resultantes da expressão matemática Lei do Seno, e ainda, que quanto menor a espessura inicial (s0) da chapa, menor a variação dos valores medidos e calculados. A análise das Forças (FX, FY e FZ) resultantes do processo SPIF mostram que quanto maior o Incremento Vertical (∆Z), maior a espessura inicial (s0) da chapa, e maior do diâmetro (DT) da ferramenta de estampagem, maiores serão as Forças necessárias no SPIF. Adicionalmente, foi possível determinar os valores de Atrito (µ), obtidos em função das Forças (FX, FY e FZ) do processo SPIF. / This paper presents a study of the Incremental Sheet Forming process, in Brass C-268 of different thicknesses (s0: 0.50, 0.70 and 1.00 mm), motivated by non-observance of research of this raw material in this sheet forming process. Currently, this material has great application in the manufacture of household items (plates, platters, etc.) and hardware for building (locks, vats, etc.), wind musical instruments and automotive radiator cores, having thus, a large industrial application field, and potential for the applications of the Incremental Sheet Forming process. The research is based on the characterization of raw materials, to obtain data such as Flow Curves, Anisotropy Indices (r), Forming Limit Curve and in Incremental Sheet Forming experiments, performed on a machine dedicated to this forming process. For the realization of the experiments, Vertical Increments with different values were used (∆Z: 0.10, 0.50 e 1.00 mm), As well as two forming tools (DT: Ø10 e Ø15 mm). Two different geometric forms were applied: Cone Frustum and Pyramid Frustum, both with radial profile of vertical walls. In all, 15 different SPIF experiments were performed. The experiments were carried out in a machine dedicated to the process, able to acquire the values of Force (FX, FY e FZ) during the tests. With the realization of SPIF experiments, it was possible to elaborate the Fracture Forming Line – FFL of Brass C-268 sheet, In the three thicknesses investigated, Where the results indicate higher values of true strain (1 vs 2), when compared to the FLC values. Additionally, the FFL of the three sheet thicknesses analyzed, indicate the values of the highest true deformations (1) very close, evidencing in this case, that the decrease of Vertical Increment (∆Z) is more relevant for the forming than the increase in sheet thickness. The Cone Frustum and Pyramid Frustum geometries presented tolerable geometric discrepancies in relation to the projected profile, more different from each other, influenced by different springback of each geometry. However, their fractures presented the same behavior, meridional direction propagation. The SPIF experiments performed with the forming tool with Ø10mm provided the greatest depths. The final thickness (s1) measurement near the fractured regions, proved the measured values did not exceed the respective values resulting from the mathematical expression Sine Law, and also, that the lower the initial thickness (s0) of sheet, lower the variation of the measured and calculated values. Analysis of Forces (FX, FY e FZ) resulting from the SPIF process, show that the larger the Vertical Increment (∆Z), larger the initial thickness (s0) of the sheet, and larger diameter (DT) of the forming tool, larger will be the necessary forces in SPIF. In addition, it was possible to determine the values of Friction (µ), obtained in function of the SPIF Forces (FX, FY e FZ).

Le domaine général de la thèse est l’analyse de sensibilité de fonctions boîte noire. L’analyse de sensibilité étudie comment la variation d’une sortie peut être reliée à la variation des entrées. C’est un outil important dans la construction, l’analyse et l’optimisation des expériences numériques (computer experiments).Nous présentons tout d’abord l’indice d’interaction total, qui est utile pour le criblage d’interactions. Plusieurs méthodes d’estimation sont proposées. Leurs propriétés sont étudiées au plan théorique et par des simulations.Le chapitre suivant concerne l’analyse de sensibilité pour des modèles avec des entrées fonctionnelles et une sortie scalaire. Une approche séquentielle très économique est présentée, qui permet non seulement de retrouver la sensibilité de entrées fonctionnelles globalement, mais aussi d’identifier les régions d’intérêt dans leur domaine de définition.Un troisième concept est proposé, les support index functions, mesurant la sensibilité d’une entrée sur tout le support de sa loi de probabilité.Finalement les trois méthodes sont appliquées avec succès à l’analyse de sensibilité de modèles d’emboutissage. / The general field of the thesis is the sensitivity analysis of black-box functions. Sensitivity analysis studies how the variation of the output can be apportioned to the variation of input sources. It is an important tool in the construction, analysis, and optimization of computer experiments.The total interaction index is presented, which can be used for the screening of interactions. Several variance-based estimation methods are suggested. Their properties are analyzed theoretically as well as on simulations.A further chapter concerns the sensitivity analysis for models that can take functions as input variables and return a scalar value as output. A very economical sequential approach is presented, which not only discovers the sensitivity of those functional variables as a whole but identifies relevant regions in the functional domain.As a third concept, support index functions, functions of sensitivity indices over the input distribution support, are suggested.Finally, all three methods are successfully applied in the sensitivity analysis of sheet metal forming models.

The thesis deals with the design of a technological process for the production a rotationally symmetrical component, which is part of the body for the chassis ball joint of a passenger car. Thesis was developed on request and in cooperation with THK RHYTHM Automotive Czech a.s. On the basis of a literary study, a technological process consisting of 10 operations was designed and elaborated. For the prototype production of the component, a four-column hydraulic press SHPFS 250, with a nominal force 2500 kN, was selected and price offer were prepared. For each of ten operations a prototype tool was designed and prepared assembly drawings. To reduce costs, a single die set was designed to allow all tools to be clamped. The total cost of acquisition of the prototype hydraulic press and tools was set at CZK 2,672,950.