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.

Computer-Aided Analysis of the Deformations and Temperatures in Strip Rolling

Abstract: This paper describes the principles and the application of two mathematical models, developed for predicting the significant variables of the strip rolling process. The first model and the associated computer program ROLING can estimate the roll-separating force and the roll torque. This model includes the most up-to-date analyses of (a) the plastic deformation in the strip, (b) the elastic compression and recovery of the strip before and after rolling, and (c) the elastic deformation of the rolls. The second model and the associated computer program ROLTEM have been developed to simulate the metal flow and temperatures in strip rolling. They consider simultaneous heat generation, heat transport, and heat transfer during rolling using a finite-difference algorithm. The predictions made by the computer programs ROLING and ROLTEM have been compared with existing experimental data. The results indicate that the agreement of theoretical predictions with experimental results is well within acceptable engineering accuracy.

State of the art electrical discharge machining (EDM)

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.

Metal Forming and the Finite-Element Method

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.

The yield stress—a review or ‘παντα ρει’—everything flows?

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 (