Shop : Rezensionsexemplar
Shop
Rezensionsexemplar
Kerim Işık
Modelling and characterization of damage and fracture in sheet-bulk metal forming
Sheet-bulk metal forming differs from the conventional sheet forming processes, in the application of the bulk forming operations on the sheet material. Although the initial workpiece is a sheet blank, occurrence of the three-dimensional stress/strain states requires a revise of the basic assumptions and available material models for the conventional sheet forming processes.
In this study, necessary material characterization techniques for the available damage models are developed to predict damage and fracture during sheet-bulk forming processes. Two damage models, namely Gurson's porous plasticity and Lemaitre's continuum damage model, are investigated. A direct material characterization methodology for Gurson model and an inverse parameter identification methodology for Lemaitre model are introduced. The characterization tests are enriched by adding the shear cutting test to identify through-thickness shear behavior and shear related model parameters. A new fracture criterion, which is originated from the experimental observations related to normal and shear fracture, is introduced. The simplified structure of this criterion allows a rapid characterization for the material parameters.
The models' predictive performances are compared for three sheet-bulk forming processes, namely local indentation, local ploughing and sheet upsetting. The results show the impact of the modelling capability for the void decrease under compressive stress states on the prediction performance. The predictions with Gurson model, which provides the void content reduction under compression, are closer to the experimental observations compared to the other models. The newly introduced fracture criterion provides fair results considering the reduced effort for the parameter identification.
In this study, necessary material characterization techniques for the available damage models are developed to predict damage and fracture during sheet-bulk forming processes. Two damage models, namely Gurson's porous plasticity and Lemaitre's continuum damage model, are investigated. A direct material characterization methodology for Gurson model and an inverse parameter identification methodology for Lemaitre model are introduced. The characterization tests are enriched by adding the shear cutting test to identify through-thickness shear behavior and shear related model parameters. A new fracture criterion, which is originated from the experimental observations related to normal and shear fracture, is introduced. The simplified structure of this criterion allows a rapid characterization for the material parameters.
The models' predictive performances are compared for three sheet-bulk forming processes, namely local indentation, local ploughing and sheet upsetting. The results show the impact of the modelling capability for the void decrease under compressive stress states on the prediction performance. The predictions with Gurson model, which provides the void content reduction under compression, are closer to the experimental observations compared to the other models. The newly introduced fracture criterion provides fair results considering the reduced effort for the parameter identification.
Schlagwörter: Fracture; damage; metal forming; formability
Shaker Verlag GmbHAm Langen Graben 15a52353 Düren
Mo. - Do. 8:00 Uhr bis 16:00 UhrFr. 8:00 Uhr bis 15:00 Uhr
Kontaktieren Sie uns. Wir helfen Ihnen gerne weiter.
