Department of Manufacturing Engineering
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Browsing Department of Manufacturing Engineering by Author "ÇELİK, Gökhan"
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Item EXPERIMENTAL INVESTIGATION OF INFLUENCE PARAMETERS ON FORMING LIMIT DIAGRAMS OF ALUMINUM ALLOY-AL 2024(2013-04-22) ÇELİK, Gökhan; KAFTANOĞLU, Bilgin; KARADOĞAN, CelalettinSheet metal forming is the key word for aerospace, automobile and aeronautics industry. To fulfill the customer expectations, safety requirements and market competitions, sheet metal forming processes must be well analyzed before production. At this stage, importance of material characterization and finite element (FE) simulations arise. This study is focused on combination of material characterization and FEA (Finite Element Analyses) of sheet metals to be able to make improvements of sheet metal while considering cost and quality. On the material characterization parts of the study, simple tension tests, hydraulic bulge tests (HBT) and forming limit diagrams are determined for Al2024 aluminum alloy. HBT is obtained using a new specialized code and compared to the simple tension tests. High accuracy mechanical extensometers are used to obtain instantaneous deformation during tensile test and similarly high accuracy CCD cameras are used to obtain material deformation during determination of FLDs and flow curves from HBT. FE studies are performed to validate experimental studies and to determine coefficient of frictions of different lubricants. Analyses are carried out using a commercial FE package, Marc Mentat 2007® . Material inputs are supplied from experimental uniaxial and hydraulic bulge tests. Flow curve validations are performed comparing HBT and uniaxial tensile tests up to 0.15 strains. Experiments revealed that initial material thickness and lubrication has a significant effect on formability window of aluminum sheets and speed of punch has no great effect on limits of aluminum formability since Al2024 is a strain rate independent material. Beside these, higher strains than uniaxial tensile test are obtained in HBT with new developed code.