Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 10Citation - Scopus: 14The Precise Determination of the Johnson-Cook Material and Damage Model Parameters and Mechanical Properties of an Aluminum 7068-T651 Alloy(ASME, 2019-03-12) Bal, B.; Karaveli, K. K.; Cetin, B.; Gumus, B.Al 7068-T651 alloy is one of the recently developed materials used mostly in the defense industry due to its high strength, toughness, and low weight compared to steels. The aim of this study is to identify the Johnson-Cook (J-C) material model parameters, the accurate Johnson-Cook (J-C) damage parameters, D-1, D-2, and D-3 of the Al 7068-T651 alloy for finite element analysis-based simulation techniques, together with other damage parameters, D-4 and D-5. In order to determine D-1, D-2, and D-3, tensile tests were conducted on notched and smooth specimens at medium strain rate, 10(0) s(-1), and tests were repeated seven times to ensure the consistency of the results both in the rolling direction and perpendicular to the rolling direction. To determine D-4 and D-5 further, tensile tests were conducted on specimens at high strain rate (10(2) s(-1)) and temperature (300 degrees C) by means of the Gleeble thermal-mechanical physical simulation system. The final areas of fractured specimens were calculated through optical microscopy. The effects of stress triaxiality factor, rolling direction, strain rate, and temperature on the mechanical properties of the Al 7068-T651 alloy were also investigated. Damage parameters were calculated via the Levenberg-Marquardt optimization method. From all the aforementioned experimental work, J-C material model parameters were determined. In this article, J-C damage model constants, based on maximum and minimum equivalent strain values, were also reported which can be utilized for the simulation of different applications.Article Citation - WoS: 58Citation - Scopus: 73Removal of Heavy Metals from Aluminum Anodic Oxidation Wastewaters by Membrane Filtration(Springer Heidelberg, 2018-05-27) Ates, Nuray; Uzal, NigmetAluminum manufacturing has been reported as one of the largest industries and wastewater produced from the aluminum industry may cause significant environmental problems due to variable pH, high heavy metal concentration, conductivity, and organic load. The management of this wastewater with a high pollution load is of great importance for practitioners in the aluminum sector. There are hardly any studies available on membrane treatment of wastewater originated from anodic oxidation. The aim of this study is to evaluate the best treatment and reuse alternative for aluminum industry wastewater using membrane filtration. Additionally, the performance of chemical precipitation, which is the existing treatment used in the aluminum facility, was also compared with membrane filtration. Wastewater originated from anodic oxidation coating process of an aluminum profile manufacturing facility in Kayseri (Turkey) was used in the experiments. The characterization of raw wastewater was in very low pH (e.g., 3) with high aluminum concentration and conductivity values. Membrane experiments were carried out with ultrafiltration (PTUF), nanofiltration (NF270), and reverse osmosis (SW30) membranes with MWCO 5000, 200-400, and 100 Da, respectively. For the chemical precipitation experiments, FeCl3 and FeSO4 chemicals presented lower removal performances for aluminum and chromium, which were below 35% at ambient wastewater pH 3. The membrane filtration experimental results show that, both NF and RO membranes tested could effectively remove aluminum, total chromium and nickel (> 90%) from the aluminum production wastewater. The RO (SW30) membrane showed a slightly higher performance at 20 bar operating pressure in terms of conductivity removal values (90%) than the NF 270 membrane (87%). Although similar removal performances were observed for heavy metals and conductivity by NF270 and SW30, significantly higher fluxes were obtained in NF270 membrane filtration at any pressure that there were more than three times the flux values in SW30 membrane filtration. Due to the lower heavy metal (< 65%) and conductivity (< 30%) removal performances of UF membrane, it could be evaluated as pretreatment followed by NF filtration to protect and extend NF membrane life. The water treated by both NF and RO could be recycled back into the process to be reused with economic and environmental benefits.