Department of Manufacturing Engineering
Permanent URI for this collection
Browse
Browsing Department of Manufacturing Engineering by Author "ALKAŞ, Celal Onur"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
Item EXPERIMENTAL AND NUMERICAL STUDY ON STRETCH FORMING PROCESS(2013-06-20) ALKAŞ, Celal Onur; KARADOĞAN, Celalettin; ŞİMŞİR, CanerStretch forming process is commonly used in the aircraft industry for the manufacturing of large sheet panels. The success of this process is highly dependent on the process parameters like mechanical properties of sheet material, the friction condition between tools-part interfaces and relative motions between tool and jaws. Determining the best parameters by trial - error procedure is quite difficult and costly, so that finite element analysis is needed. The scope of this study is to establish finite element model (FEM) for stretch forming process. For this purpose, accurate material and reliable friction modeling are required. Material characterization tests of mostly used aluminum alloys are conducted to prepare input to the model. Standard tensile, stack compression, hydraulic bulge test (HBT) and forming limit diagram (FLD) tests are performed in order to identify deformation behavior and anisotropy properties of aluminum sheet materials. High accuracy CCD cameras are used to obtain material deformation during determination of FLDs and flow curves from HBT. Also, friction coefficients are determined for various lubrication conditions encountered in stretch forming processes using inverse based analysis. Using these inputs, numerical model of the process is established by FEM for three basic stretching tool motions, which are; stretching the sheet by jaw, stretching the sheet by form die and finally stretching the sheet material by synchronized motion of both tools. In order to improve the model and validate the analyses results, experimental work is also performed in which the deformation of the sheet is measured optically using GOM-Argus® 3- D deformation measurement device. Then, three selected aerospace sheet parts were analyzed and success of the model for industrial applications is proved.