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    Application of Digital Image Correlation technique to Erichsen Cupping Test
    (Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Aydin, Murat; Wu, Xin; Cetinkaya, Kerim; Yasar, Mustafa; Kadi, Ibrahim
    Digital Image Correlation (DIC) technique is a powerful and useful tool in many industrial applications for both scientific and commercial purposes. It has been widely used for mechanical tests to understand the behaviour of material. In this study, 3D DIC technique was adopted to Erichsen Cupping Test (ECT) to measure the fracture cup height and demonstrate its benefits over traditional measurement techniques. Ck75 steel sheet with various material thickness was used in the experiments. The flat specimens were fixed in a closed die set-up and stretched along two directions until fracture. All the experiments were performed on a manually operated hydraulic press with a constant cross-head displacement and recorded with high resolution cameras. Finally, to determine the fractured cup heights, the accurate and satisfactory results were obtained through DIC measurements. The full-field thickness distribution and the maximum fracture forces were also determined. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.
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    Effects of Die Corner Radius and Temperature on the Formability of AA7075-T6 Alloy
    (Chinese Acad Sciences, Inst Metal Research, 2013) Evlen, Hatice; Kadi, Ibrahim; Yasar, Mustafa
    This study focused on the formability of aluminium alloy (7075-T6) sheets through hydroforming route. Formability of these sheets was tested using a warm forming setup at three different temperatures and four different die corner radii. Forming limit diagrams (FLD) were generated by measuring the grids of the sheet formed. The results show that the forming limit of AA7075-T6 can be significantly improved when the blank was heated to 140-250 degrees C. It was also observed that as the temperature increases above 140 degrees C, dome height began to decrease. Also the results indicated that both the die corner radius and temperature have a significant effect on the stress-strain curve and warm forming of AA7075-T6 sheets. Thus, with the temperature increased from room temperature (RT) to 140 degrees C, the flow stress decreased and the strain increased, hence, the formability is enhanced. However, further increase in temperature causes decreases the flow stress and strain. Similar changes of the flow curve were seen in die corner radius. Decreasing the die corner radius decreases the flow stress and increase the strain. Moreover, an equation was obtained by establishing correlations between the experimental parameters and their results. In this way, it became possible to make predictions.
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    The Relation Between Meteorological Factors and Pollutants Concentrations in Karabuk City
    (Gazi Univ, 2007) Celik, M. Bahattin; Kadi, Ibrahim
    Karabuk, situated in the northwest of Turkey, is among the cities which suffer most from the air pollution in Turkey. Due to the heavy industrial foundations and the usage of low quality coal for heating purposes, air pollution has been the primary environmental problem in Karabuk. Meteorological factors are known to be effective in decreasing air pollution, but the meteorological properties of Karabuk do not allow for the diminishment of air pollution. In this study, the relationship between SO2 and particulate matter; and wind speed, relative humidity and air temperature has been investigated from 1998 to 2001 on the bases of 24-hour continuous measurements. The relationship between air pollution and the meteorological factors was statistically analyzed. According to the results of the analysis, for some years, there is a moderate and weak level relation between meteorological factors and particulate matter concentrations in Karabuk city.