Browsing by Author "Seyedzavvar, M."

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Citation - Scopus: 5
Micro-Wedm of Ni55.8ti Shape Memory Superalloy: Experimental Investigation and Optimisation
(Inderscience Publishers, 2021) Akar, S.; Seyedzavvar, M.; Kiliç, S.E.; Meshri, H.A.M.; 315516; 06.06. Makine Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Nickel-titanium superalloy has gained significant acceptance for engineering applications as orthotropic implants, orthodontic devices, automatic actuators, etc. Considering the unique properties of these alloys, such as high hardness, toughness, strain hardening, and development of straininduced martensite, micro-wire electro-discharge machining (μ-WEDM) process has been accepted as one of the main options for cutting intricate shapes of these alloys in micro-scale. This paper presents the results of a comprehensive study to address the material removal rate (MRR) and surface integrity of Ni55.8Ti shape memory superalloy (SMA) in the μ-WEDM process. The effects of discharge current, pulse on-time, pulse off-time, and servo voltage on the performance of this process, including MRR, white layer thickness, surface roughness, and micro-hardness of the machined surface, were investigated by multi-regression analysis using response surface methodology (RSM). The optimisation of input parameters based on the gradient and the swarm optimisation algorithms were also conducted to maximise the MRR and minimise the white layer thickness, surface roughness, and micro-hardness of the machined samples. © 2021 Inderscience Enterprises Ltd.. All rights reserved.
Citation - Scopus: 2
Numerical Simulation and Experimental Investigation: Metal Spinning Process of Stepped Thin-Walled Cylindrical Workpiece
(Murat Yakar, 2022) Seyedzavvar, M.; Akar, S.; Abbasi, H.; 315516; 06.06. Makine Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Many equipment and devices utilized in the aerospace industry are formed as symmetric parts through high plastic deformation of high strength sheet metal alloys with low thickness. Considering the inherent advantages of the spinning process of simple tooling and concentrated deformation loading, this process can be considered as one of the main options in producing these thin-sectioned lightweight parts. In this study, a Finite Element (FE) model has been developed to simulate the formation of a stepped thin-walled cylindrical workpiece of AISI 316 stainless steel alloy by spinning process. The FE simulation results were employed to investigate the effects of process parameters, including feed rate of the roller and rotational velocity of the mandrel on the distribution of stress and strain in the sheet metal, wrinkling failure, and thinning of the sheet metal during deformation. Experiments were carried out using selective input parameters based on the results of FE simulations. The comparison between FE simulations and experiments revealed that the developed model could predict the thinning of the sheet metals with over 93 % accuracy. Additionally, a good agreement between the experimentally deformed sheet configurations with those resulting from finite element simulations has been observed. © Author(s) 2022.