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Taylan Altan

Bio: Taylan Altan is an academic researcher from Ohio State University. The author has contributed to research in topics: Forging & Finite element method. The author has an hindex of 59, co-authored 270 publications receiving 14494 citations. Previous affiliations of Taylan Altan include University College of Engineering & DuPont.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a finite element based Inverse analysis technique was developed to determine the flow stress and friction at the tool/workplace interface simultaneously from one set of material tests, aimed at minimizing the error between experimental data and predictions made by rigid-plastic finite element simulations.

32 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a benchmark test to evaluate the performance of candidate lubricants for stamping operations involving the ironing process, and applied it to the application of the test to screen candidate lubes for high speed progressive or transfer die operations involving ironing.
Abstract: Lubricants are employed in stamping operations in order to (a) improve the material flow into the die cavity, (b) reduce wear and galling in the die and (c) obtain good surface finish of the part. Process conditions such as high temperatures and pressures could cause the lubricant to fail, thus resulting in galling or tearing of the part, damage to the tooling, and lost production. Therefore, selection of an appropriate lubricant based on the process conditions is important in the stamping industry. Several benchmark tests emulating stamping operations have been developed and are used to evaluate the performance of candidate lubricants. The major drawback of most of these tests is their inability to emulate high contact pressures and sliding velocities, which are crucial parameters for lubricity, especially in the case of high-speed progressive or transfer die operations involving ironing. Moreover, most of these tests are conducted at room temperature, while in reality; the process temperature can reach as high as 200 °C. The ironing tribotest developed at the Engineering Research Center for Net Shape Manufacturing (ERC/NSM) induces high contact pressures and temperatures, thus emulating the conditions in a production environment. Application of the test to screen candidate lubricants for stamping operations involving the ironing process is discussed in this paper.

32 citations

Journal ArticleDOI
TL;DR: In this article, finite element (FE) based numerical modeling and physical modelling with plasticine are presented as process design tools in cold forging of bevel gears, and the results from the process simulation are then used as load input data for a punch stress analysis.

31 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a Lagrangian finite element method of fracture and fragmentation in brittle materials is developed, where a cohesive-law fracture model is used to propagate multiple cracks along arbitrary paths.

1,970 citations

Journal ArticleDOI
TL;DR: Electrical discharge machining (EDM) has been continuously evolving from a mere tool and die making process to a micro-scale application machining alternative attracting a significant amount of research interests as mentioned in this paper.
Abstract: Electrical discharge machining (EDM) is a well-established machining option for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining processes. The non-contact machining technique has been continuously evolving from a mere tool and die making process to a micro-scale application machining alternative attracting a significant amount of research interests. In recent years, EDM researchers have explored a number of ways to improve the sparking efficiency including some unique experimental concepts that depart from the EDM traditional sparking phenomenon. Despite a range of different approaches, this new research shares the same objectives of achieving more efficient metal removal coupled with a reduction in tool wear and improved surface quality. This paper reviews the research work carried out from the inception to the development of die-sinking EDM within the past decade. It reports on the EDM research relating to improving performance measures, optimising the process variables, monitoring and control the sparking process, simplifying the electrode design and manufacture. A range of EDM applications are highlighted together with the development of hybrid machining processes. The final part of the paper discusses these developments and outlines the trends for future EDM research.

1,421 citations

Book
09 Mar 1989
TL;DR: In this paper, the finite element method was used to analyze the metal forming process and its properties, including plasticity, viscoplasticity, and plane-strain problems.
Abstract: Introduction Metal forming process Analysis and technology in metal forming Plasticity and viscoplasticity Methods of analysis The finite element method (1) The finite element method (2) Plane-strain problems Axisymmetric isothermal forging Steady state processes of extrusion and drawing Sheet metal forming Thermo-viscoplastic analysis Compaction and forging of porous metals Three dimensional problems Preform design in metal forming Solid formulation, comparison of two formulations, and concluding remarks Index.

1,226 citations

Journal ArticleDOI
TL;DR: In this article, the boundary layer flow induced in a nanofluid due to a linearly stretching sheet is studied numerically and the transport equations include the effects of Brownian motion and thermophoresis.

1,086 citations

Journal ArticleDOI
TL;DR: In this paper, the authors give an account of the development of the idea of yield stress for solids, soft solids and structured liquids from the beginning of this century to the present time.
Abstract: An account is given of the development of the idea of a yield stress for solids, soft solids and structured liquids from the beginning of this century to the present time. Originally, it was accepted that the yield stress of a solid was essentially the point at which, when the applied stress was increased, the deforming solid first began to show liquid-like behaviour, i.e. continual deformation. In the same way, the yield stress of a structured liquid was originally seen as the point at which, when decreasing the applied stress, solid-like behaviour was first noticed, i.e. no continual deformation. However as time went on, and experimental capabilities increased, it became clear, first for solids and lately for soft solids and structured liquids, that although there is usually a small range of stress over which the mechanical properties change dramatically (an apparent yield stress), these materials nevertheless show slow but continual steady deformation when stressed for a long time below this level, having shown an initial linear elastic response to the applied stress. At the lowest stresses, this creep behaviour for solids, soft solids and structured liquids can be described by a Newtonian-plateau viscosity. As the stress is increased the flow behaviour usually changes into a power-law dependence of steady-state shear rate on shear stress. For structured liquids and soft solids, this behaviour generally gives way to Newtonian behaviour at the highest stresses. For structured liquids this transition from very high (creep) viscosity (>106 Pa.s) to mobile liquid (

950 citations