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Analysis of failure in sheet metal stamping

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Resumo:In the past, forming dies were developed through a trial-and-error process, where failures were identified and the die shape was subsequently adjusted. With the advent of the Finite Element Method (FEM), this process became more efficient, as FEM could be used to simulate and analyze forming results. Meanwhile, the tightening of automotive emission standards has increased the demand for more suitable materials, leading to stricter safety margins to achieve the desired weight reduction. In this work, the FEM will be employed to assess whether the failures observed in the industrial cold stamping process could have been predicted. To achieve this, several tensile tests will be conducted to characterize the material properties of two Ferritic Stainless Steel (FSS), EN 1.4509 and EN 1.4512. Using Digital Image Correlation (DIC), the anisotropy coefficients will be obtained and used to model the Barlat (1989) and Hill (1948) yield criteria. The Forming Limit Diagram (FLD) will be predicted through Abspoel and Keeler and Brazier methods. Finally, FEM simulations will be carried out using Ansys Forming software on two different stamped parts. The first part involves seven forming operations, while the second is limited to only the initial operation. In the first part, an increased tendency for wrinkling is observed near the notches, resulting in a local increase in thickness. In the second part, two of three failures observed in industrial production are successfully reproduced with the default parameters. Subsequently, the Lankford Ratio is varied by ±10%, which leads to the occurrence of the final failure. This highlights a strong dependency on the Lankford Ratio.
Autores principais:Kawakami, Thiago Fernando
Assunto:Finite Element Method cold stamping tensile tests Ferritic stainless steels Digital image correlation Anisotropy Yield criterion Forming limit diagram
Ano:2025
País:Portugal
Tipo de documento:dissertação de mestrado
Tipo de acesso:acesso aberto
Instituição associada:Instituto Politécnico de Bragança
Idioma:português
Origem:Biblioteca Digital do IPB

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