Author
Bilgin Kaftanoğlu
Other affiliations: Imperial College London, Middle East Technical University, Oklahoma State University–Stillwater
Bio: Bilgin Kaftanoğlu is an academic researcher from Atılım University. The author has contributed to research in topics: Boron nitride & Deep drawing. The author has an hindex of 14, co-authored 53 publications receiving 960 citations. Previous affiliations of Bilgin Kaftanoğlu include Imperial College London & Middle East Technical University.
Topics: Boron nitride, Deep drawing, Sheet metal, Machining, Adsorption
Papers published on a yearly basis
Papers
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TL;DR: In this paper, a 3D finite element model was used to predict chip formation, forces, temperatures and tool wear on multi-layer coated inserts, and a modified material model with strain softening effect was developed to simulate chip formation with finite element analysis and investigate temperature fields for coated inserts.
194 citations
TL;DR: In this article, the effects of machining parameters on surface roughness, burr formation, and tool wear for uncoated and cBN coated micro-tools are investigated, and finite element modeling is utilized to predict forces, temperatures, and wear rate for un-coated, cBN-covered, and tungsten carbide micro-tool edges.
119 citations
TL;DR: In this article, an enhanced analytic elasto-plastic model is presented using the superposition of thermal and mechanical stresses on the workpiece, followed by a relaxation procedure.
102 citations
TL;DR: In this paper, the Dubinin-Astakhov adsorption equilibrium model was fitted to experimental data with an acceptable error limit, and the isosteric heat of water on zeolite has been calculated using the Clausius-Clapeyron equation as a function of the adorption capacity.
87 citations
TL;DR: In this article, a rate-independent anisotropic plasticity model accounting the Bauschinger effect is presented and applied in the FE forming and springback analyses, where the material strain-hardening behavior is simulated by an additive backstress form of the nonlinear kinematic hardening rule and model parameters are computed explicitly based on the stress-strain curve in the sheet rolling direction.
70 citations
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TL;DR: In this paper, the authors provide an overview of machining induced surface integrity in titanium and nickel alloys and conclude that further modeling studies are needed to create predictive physics-based models that is in good agreement with reliable experiments.
Abstract: Titanium and nickel alloys represent a significant metal portion of the aircraft structural and engine components. When these critical structural components in aerospace industry are manufactured with the objective to reach high reliability levels, surface integrity is one of the most relevant parameters used for evaluating the quality of finish machined surfaces. The residual stresses and surface alteration (white etch layer and depth of work hardening) induced by machining of titanium alloys and nickel-based alloys are very critical due to safety and sustainability concerns. This review paper provides an overview of machining induced surface integrity in titanium and nickel alloys. There are many different types of surface integrity problems reported in literature, and among these, residual stresses, white layer and work hardening layers, as well as microstructural alterations can be studied in order to improve surface qualities of end products. Many parameters affect the surface quality of workpieces, and cutting speed, feed rate, depth of cut, tool geometry and preparation, tool wear, and workpiece properties are among the most important ones worth to investigate. Experimental and empirical studies as well as analytical and Finite Element modeling based approaches are offered in order to better understand machining induced surface integrity. In the current state-of-the-art however, a comprehensive and systematic modeling approach based on the process physics and applicable to the industrial processes is still missing. It is concluded that further modeling studies are needed to create predictive physics-based models that is in good agreement with reliable experiments, while explaining the effects of many parameters, for machining of titanium alloys and nickel-based alloys.
986 citations
TL;DR: In this article, a survey of the terminal ballistics aspects and the penetration mechanics viewpoint of the interaction of penetrators and targets is presented, with a focus on the impact of the penetration on the target.
782 citations
TL;DR: A three-year study by the CIRP's Collaborative Working Group on Surface Integrity and Functional Performance of Components as discussed by the authors reported recent progress in experimental and theoretical investigations on surface integrity in material removal processes.
769 citations
TL;DR: In this article, the state-of-the-art in predictive performance models for machining operations is presented, and a critical assessment of the relevant modelling techniques and their applicability and/or limitations for the prediction of the complex machining operation performed in industry.
622 citations
TL;DR: In this article, the effect of material constitutive models and elastic-viscoplastic finite element formulation on serrated chip formation for modeling of machining Ti-6Al-4V titanium alloy is investigated.
Abstract: Titanium alloys present superior properties such as high strength-to-weight ratio and resistance to corrosion but, possess poor machinability. In this study, influence of material constitutive models and elastic–viscoplastic finite element formulation on serrated chip formation for modeling of machining Ti–6Al–4V titanium alloy is investigated. Temperature-dependent flow softening based modified material models are proposed where flow softening phenomenon, strain hardening and thermal softening effects and their interactions are coupled. Orthogonal cutting experiments have been conducted with uncoated carbide (WC/Co) and TiAlN coated carbide cutting tools. Temperature-dependent flow softening parameters are validated on a set of experimental data by using measured cutting forces and chip morphology. Finite Element simulations are validated with experimental results at two different rake angles, three different undeformed chip thickness values and two different cutting speeds. The results reveal that material flow stress and finite element formulation greatly affects not only chip formation mechanism but also forces and temperatures predicted. Chip formation process for adiabatic shearing in machining Ti–6Al–4V alloy is successfully simulated using finite element models without implementing damage models.
409 citations