As competition in the car market increases, the techniques for car manufacturing are developed and becomes more advanced to be able to keep up with the pace. The development process of car body components has shifted over the years to involve more simulation driven testing than ever before to save time and money in the early stages of development. As the importance of reliable sheet metal forming simulations grows, inconsistencies between simulations and physical stamping can be detrimental to the development time if stamping dies need to be reworked because of poor correlation between physics and simulations.                        The aim of this study is to improve the coherence between physical stamping and the simulation software used by Volvo Cars. The coherence is determined by studying different properties of the result in simulations and comparing them to measurements taken on the corresponding physical stamped parts. A comparison was done between the current standard simulation software, Autoform Forming R8 and a beta version of Autoform Forming R10. The objectives of this study were to compare the sheet thickness, strain, draw-in and ability to predict material failure between the two simulation software to see which of them correlate best to the physical measured parts.                       The workflow consisted of initially setting up the simulations in Autoform Forming R8. Some of the simulations could begin testing right away, while others required needed some geometry rework as the physical tested parts had been stamped with modified stamping dies. When the simulation setups were completed copies of the simulations were taken and run on Autoform Forming R10 to compare with. The simulations were run with a varied Triboform friction models and some of the simulations were run using symmetry to reduce the simulation time. When data was compared Autoform Forming was used when possible and when additional tools were needed the simulated geometries were exported and compared in software such as SVIEW and GOM Correlate.                       The result showed relatively low differences in the comparisons of sheet thickness and major and minor strain as neither of the simulations seemed to give more accurate values compared to the measurements. A slight improvement in the draw-in comparison was found for the Autoform Forming R10 compared to the R8 simulation. In the material failure prediction a major difference was found where the Autoform Forming R10 simulations were better at determining splits than R8. However the splits were only discovered with 2 of the 4 tested friction models in the R10 simulations while the 1 of the 4 simulations indicated risks for a split in the R8 simulation.                       In conclusion the simulations run on Autoform Forming R10 seem to be better at predicting splits and draw-in dimensions while no major differences were found in the comparisons of strain and sheet thickness.

Die Blechumformungsimulation hat sich in den letzten 25 Jahren stark weiterentwickelt. Die Simulation des gesamten Tiefziehprozesses einschließlich Beschneiden, Bördeln und Rückfedern ist bei den meisten Automobilherstellern und Werkzeugbaubetrieben ein Standardverfahren. Die Verwendung von LS-DYNA, einem der genauesten Löser für die Blechumformung, erfordert noch einiges an Expertenwissen, was die Verwendung für Methodenplaner in ihrer täglichen Arbeit erschwert. Aus diesem Grund hat Ansys eine spezielle Software für die Simulation der Blechumformung entwickelt: „Ansys Forming“. Ansys Forming ist eine benutzerfreundliche GUI zum Aufbau und zur Auswertung einer Blechumformungssimulation ohne Expertenkenntnisse von LS-DYNA.

Sheet metal forming simulation has greatly evolved over the last 25 years. Simulation of the entire deep drawing process including trimming, flanging and springback is a standard procedure at most automotive OEMs and tool shops. Using LS-DYNA, one of the most accurate solvers for sheet metal forming, still needs some expert knowledge, which makes it difficult to use for method engineers in their day-to-day work. Therefore, Ansys has been developing a dedicated application for sheet metal forming simulation, “Ansys Forming”.

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Os processos de conformação de metais, apesar de sua extensa aplicação na indústria, tem seus projetos baseados principalmente em técnicas experimentais. Com o desenvolvimento e facilidade de acesso a computadores mais potentes, tornou-se viável a utilização de soluções numéricas como ferramentas de otimização das características do produto, do processo, bem como de seu custo. Um método numérico amplamente utilizado para simulação do processo de conformação é o Método dos Elementos Finitos, que permite a previsão do comportamento do fluxo de material durante a operação de conformação de chapas. Considera-se um blank com perfil ideal aquele onde a peça produzida a partir de sua conformação possua uma flange constante, minimizando ou eliminando a operação de retirada da rebarba. Com o objetivo de se obter o blank com perfil ideal para operação de conformação de chapas, desenvolveu-se uma metodologia de otimização geométrica da forma do blank, que trabalha integrada a um software comercial de análise pelo Método dos Elementos Finitos, o ANSYS/LS-Dyna3D. Apresentam-se os resultados aplicados à simulação da estampagem de uma peça prismática de base quadrada, como meio de validação da metodologia de otimização proposta. / The metal forming processes have extensive industrial application although their projects are based mainly in experimental techniques. With the development of more powerful computers, the use of numerical methods to design, simulate and optimize costs of such processes has become possible. Among the numerical methods, the Finite Element Method have large application in forming simulation, since it allows the prediction of the material flow during the sheet metal forming process. Ideal blank shape is that one which produces a part with constant flange, minimizing or eliminating trimming operations. In order to determine the ideal blank shape, this work developed a methodology to blank shape optimization. This optimization methodology has been integrated to a commercial Finite Element analysis software, the ANSYS/LS-Dyna3D. The results applied to a simulation of a square cup part are showed and discussed in order to validate the proposed optimization methodology.

In this thesis the sheet metal forming effects such as plastic strain and thickness changes in the crash have been investigated by numerical analysis. The sheet metal forming histories of the components of the load path that absorbs the highest energy during a frontal crash have been considered. To find out the particular load path, the frontal crash analysis of Ford F250 Pickup has been performed at 56 kph into a rigid wall with finite element analysis without considering the forming history. The sheet metal forming simulations have been realized for each structural component building up the particular load path. After forming histories have been acquired, plastic strain and thickness distributions have been transferred to the frontal crash analysis. The frontal crash analysis of Ford F250 Pickup has been repeated by including these to introduce the effect of forming on crash response of the vehicle. The results of the simulations with and without forming effect have been compared with the physical crash test results to evaluate the sheet metal forming effect on the overall crash response. The results showed that with forming history the crash response of the vehicle and deformations of the particular components have been changed and the maximum deceleration pulse transferred to the passenger compartment has decreased. It has seen that a good agreement with physical test results has been achieved.

Deep drawing operations are crucial for metal forming operations and manufacturing. Obtaining a defect free final product with the desired mechanical properties is very important for fulfilling the customer expectations and market competitions. Wrinkling is one of the fatal and most frequent defects that must be prevented. This study focuses on understanding the phenomenon of wrinkling and probable precautions that can be applied. In this study, dynamic &ndash / explicit commercial finite element code is used to simulate deep drawing process. The numerical experiments are compared with NUMISHEET benchmarks in order to verify the reliability of the finite element code and analysis parameters. In order to understand plastic wrinkling, the effect of blank holder force is investigated. Axisymmetrical numerical models of a cup are investigated with different blank holder forces. Wrinkling instability is illustrated in energy diagrams of the process. Effect of anisotropy on wrinkling is also discussed by comparing isotropic and anisotropic numerical experiments with the material as steel. Different drawbead models, both equivalent and physical, are implied to the problem and results are discussed. Besides numerical analysis, experimental verification is also conducted as conventional deep drawing operation by a hydraulic press. This yields to the ability to understand the effect of blank thickness on wrinkling formation through numerical and experimental analyses. The wave formations of different sized blanks with four different thicknesses are illustrated.

The Forming Limit Diagram (FLD) is a widely used concept to represent the formability of thin metallic sheets. In sheet metal forming processes, plastic instability may occur, leading to defective products. In order to manufacture defect free products, the prediction of the forming limits of sheet metals is a very important issue. FLD&rsquo / s can be obtained by several experimental, empirical and theoretical methods. However, the suitability and the accuracy of these methods for a given material may vary. In this study, FLD&rsquo / s are predicted by simulating Nakazima test using finite element software Pam-Stamp 2G. Strain propagation phenomenon is used to evaluate the limit strains from the finite element simulations. Two different anisotropic materials, AA2024-O and SAE 1006, are considered throughout the study and for each material, 7 different specimen geometries are analyzed. Furthermore, FLD&rsquo / s are predicted by theoretical approaches namely / Keeler&rsquo / s model, maximum load criteria, Swift-Hill model and Storen-Rice model. At the end of the study, the obtained FLD&rsquo / s are compared with the experimental results. It has been found that strain propagation phenomenon results for SAE 1006 are in a good agreement with the experimental results / however it is not for AA2024-O. In addition, theoretical models show some variations depending on the material considered. It has been observed that forming limit prediction using strain propagation phenomena with FE method can substantially reduce the time and cost for experimental work and trial and error process.