Analysis of the formability of metals

Koçak, Özgür
Workpieces during cold forging fail basically due to ductile fracture. Ductile fracture can be predicted by damage models. In this study, various damage models such as Cockcroft & Latham, McClintock, Freudenthal, Rice & Tracy, Oyane, Ayada, Brozzo are investigated for their applicability to three workpiece materials: bearing steel (100Cr6), stainless steel (X5CrNiMo1810) and brass (CuZn39). The damage material parameters have been obtained by various tests such as tensile, standard compression, ring compression, compression with flanges and conical compression tests. The characterization has been assisted by finite element simulation of the various tests. It has been shown that the available damage models can predict the location of failure satisfactorily but are no able to predict the onset of failure quantitatively.


Investigation of proper specimen geometry for mode I fracture toughness testing with flattened Brazilian disc method
KELES, Cigdem; Tutluoğlu, Levend (2011-05-01)
Investigation of geometrical parameters for flattened Brazilian disc method is important, since this is a simple and attractive method for mode I fracture toughness testing on rock cores. Evaluating numerical modeling results, a parametric equation in terms of principal stresses at the center of the disc and the loading angle of the flattened end was developed. An equation was proposed for maximum stress intensity factors at critical crack lengths around stable to unstable crack propagation. Comparing fract...
Prediction of workpiece dynamics and its effects on chatter stability in milling
Budak, Erhan; Alan, Salih; Özgüven, Hasan Nevzat (2012-01-01)
The workpiece dynamics affect stability in machining of flexible parts. However, it is not a straightforward task to include it in the analysis since the workpiece dynamics continuously change due to mass removal and variation of the cutter contact. In this paper, a methodology for prediction of inprocess workpiece dynamics is presented, which is based on a structural dynamic modification using the FE model of the workpiece. The cutter location (CL) file is used to determine the removed elements at each too...
Prediction of forming limit curve at fracture for sheet metal using new ductile fracture criterion
Dizaji, Shahram Abbasnejad; Darendeliler, Haluk; KAFTANOĞLU, BİLGİN (Elsevier BV, 2018-05-01)
The application of ductile fracture criteria (DFCs) in numerical analysis of sheet metal forming processes can lead to the accurate determination of the fracture initiation. In this study, a new uncoupled ductile fracture criterion (DFC) has been developed which considers the effects of material parameters on the forming limit curves (FLCs) and can be easily implemented in the finite element codes. Two different constitutive models have been employed with the new DFC in order to evaluate the results obtaine...
Characterization of Duplex Stainless Steel Weld Metals Obtained by Hybrid Plasma-Gas Metal Arc Welding
Yurtışık, Koray; Tirkeş, Süha; Gür, Cemil Hakan; Gürbüz, Rıza (FapUNIFESP (SciELO), 2013-07-01)
Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex microstructure wi...
Shear mode fracture toughness of rock with different core-based specimen geometries
Het, Kıvanç; Tutluoğlu, Levend; Department of Mining Engineering (2014)
Shear mode fracture toughness tests on core specimens of gabbro rock were conducted. Tests were conducted under three-point bending and Brazilian type indirect compression load. In order to investigate the reasons for having different fracture toughness values with the different testing methods and geometries, modeling with ABAQUS software was conducted. Stress distributions around the mode II notches were analyzed. In order to assess which specimen geometry results in similar stress distributions as in the...
Citation Formats
Ö. Koçak, “Analysis of the formability of metals,” M.S. - Master of Science, Middle East Technical University, 2003.