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    Chemical, bioactive properties and in vitro digestibility of spray-dried fish silages: Comparison of two discard fish (Equulites klunzingeri and Carassius gibelio) silages
    (WILEY, 2018) Ozyurt, G.; Boga, M.; Ucar, Y.; Boga, E. K.; Polat, A.
    The fermented fish silages produced with Streptococcus spp., Lactobacillus brevis, Lactobacillus plantarum, Pediococcus acidilactici and Enterococcus gallinarum, and formic acid silages were compared for production of two discard fish silages (Equulites klunzingeri and Carassius gibelio). The E/NE ratio of spray-dried fish silages was determined in range of 0.80-1.10 for E.klunzingeri and 0.80-0.90 for C. gibelio silages. Pediococcus acidilactici and En. gallinarum groups had greater antioxidant activity than other silage groups. The DPPH radical scavenging ability was found as 6.14%-14.71% and 6.99%-13.36% for E.klunzingeri and C. gibelio silages, respectively. The OMD, ME and NEL values were determined in range of 69.74%-80.08%, 6.38-8.65 MJ/kg DM and 6.45-7.49 MJ/kg DM, respectively for spray-dried E.klunzingeri silages and 81.18%-86.62%, 8.97-9.61 MJ/kg DM and 7.61-8.08 MJ/kg DM, respectively, for spray-dried C. gibelio silages. According to the nutritional and chemical evaluation, spray-dried fish silages have great potential as a feed components because of high rate of digestibility and nutritious components.
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    Formability and springback characterization of TRIP800 advanced high strength steel
    (ELSEVIER SCI LTD, 2012) Toros, S.; Polat, A.; Ozturk, F.
    Springback is one of the most common problems in the sheet metal forming operation. In the literature there have been numerous studies about springback and its compensation for many material groups. Illustrations of these phenomena for the sheet metals have still been going on by using the numerical and the experimental tools. Nowadays, the finite element method is the most powerful tool for determining of the springback characterization of the sheet metals. The selection of the material models which are used in the finite element software for the simulation of the forming operation and springback are very important in terms of accurate predictions. In the present study, formability and springback characterization of the TRIP800 steel are investigated by finite element analysis method using different material models, i.e. Hill-48, Barlat-89, and YLD2000. Additionally, the capability of the Hill-48 and Barlat-89 on predicting the variation of the yield stress and anisotropy values with respect to the angle from rolling direction is investigated for different methods like Lankford parameters and ErrMin approaches. Results reveal that the variation of the yield stress and anisotropy values that obtained from experiments at different directions like 0 degrees 45 degrees, 90 degrees can be predict better with ErrMin method. Among the studied anisotropic yield criteria, YLD2000-2d has the best fit to the yield stress and anisotropy values. According the finite element simulation of V-die bending processes YLD2000-2d has the best prediction capability of the springback. (C) 2012 Elsevier Ltd. All rights reserved.
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    Strain Hardening and Strain Rate Sensitivity Behaviors of Advanced High Strength Steels
    (JOURNAL IRON STEEL RESEARCH EDITORIAL BOARD, 2013) Ozturk, F.; Polat, A.; Toros, S.; Picu, R. C.
    The mechanical properties of commercial dual phase (DP), transformation induced plasticity (TRIP), and high strength low alloy (HSLA-340) steel sheets are investigated and compared at various strain rates ranging from 0.0017 to 0.17 s(-1) at ambient temperature. TRIP steel outperforms the other two materials, having comparable ductility and twice as large strength relative to DP steel. TRIP has larger strength and much larger ductility than HSLA-340. The exceuent ductility of TRIP800 is due to its high strain hardening capability, which promotes stable plastic deformation. It is observed that the strain hardening rate in TRIP800 does not decrease to zero at failure, as common in most materials in which failure is preceded by necking.