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Subject: applications

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    Conference Object
    Predicting the Topology of the Bending Corner in Bending of Ultra High Strength Steels Through Finite Element Analysis
    (Tanger Ltd, 2019) Cetin, Baris; Billur, Eren; Baranoglu, Besim; Toptas, Ugur; Alic, Ozgur; Manufacturing Engineering; Automotive Engineering
    In bending of plates, unlike the case of sheet metal forming, a 3-D stress state is valid. Moreover, apart from the some very specific cases, the plane strain assumption is not appropriate either. Therefore; bending of thick ultra-high strength steel (UHSS) plates is a deformation process where 3-D stress and strain states exist in general. This study basically focuses on the prediction of the bending corner topology with non-linear finite element analysis method, since the laser-cut edges of the UHSS are particularly prone to edge cracking during bending operation. Within the scope of this study, an experimental set-up is designed which consists of bending tools and a servo mechanical press. The samples were bent by means of this set-up in an air-bending operation up to 90 degrees. This experimental work was followed by optical scanning measurements. And finally, the FEA results and the scanning data were compared in 3-D space. The results showed good correlation. As a future study, the 3-D strain field of the bending corner will be tried to be measured by a professional digital image correlation (DIC) system which could probably give more precise data when combined with the data from FEA.
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    Article
    Citation - WoS: 4
    Citation - Scopus: 3
    Crosslinked Polyethyleneimine-Based Structures in Different Morphologies as Promising Co2 Adsorption Systems: a Comprehensive Study
    (Wiley, 2024) Demirci, Sahin; Inger, Erk; Bhethanabotla, Venkat; Sahiner, Nurettin
    Although there are many studies on CO2 adsorption via PEI-modified carbon particles, metal-organic frameworks, zeolitic imidazolate frameworks, and silica-based porous structures, only a limited number of studies on solely cross-linked PEI-based structures. Here, the CO2 adsorption capacities of PEI-based microgels and cryogels were investigated. The effects of various parameters influencing the CO2 adsorption capacity of PEI-based structures, for example, crosslinker types, PEI types (branched [bPEI] or linear [lPEI]), adsorbent types (microgel or cryogel), chemical-modification including their complexes were examined. NaOH-treated glycerol diglycidyl ether (GDE) crosslinked lPEI microgels exhibited higher CO2 adsorption capacity among other microgels with 0.094 +/- 0.006 mmol CO2/g at 900 mm Hg, 25 degrees C with 2- and 7.5-fold increase upon pentaethylenehexamine (PEHA) modification and Ba(II) metal ion complexing, respectively. The CO2 adsorption capacity of bPEI and lPEI-based cryogels were compared and found that lPEI-GDE cryogels had higher adsorption capacity than bPEI-GDE cryogels with 0.188 +/- 0.01 mmol CO2/g at 900 mm Hg and 25 degrees C. The reuse studies revealed that NaOH-treated GDE crosslinked bPEI and lPEI microgels and cryogels showed promising potential, for example, after 10-times repeated use >50% CO2 adsorption capacity was retained. The results affirmed that PEI-based microgels and cryogels are encouraging materials for CO2 capture and reuse applications.
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    Article
    Citation - WoS: 50
    Citation - Scopus: 51
    Elemental Sulfur-Based Polymeric Materials: Synthesis and Characterization
    (Wiley-blackwell, 2016) Salman, Mohamed Khalifa; Karabay, Baris; Karabay, Lutfiye Canan; Cihaner, Atilla
    New elemental sulfur-based polymeric materials called poly(sulfur-random-divinylbenzene) [poly(S-r-DVB)] were synthesized by ring opening polymerization via inverse vulcanization technique in the presence of a mixture of o-, m-, and p-diviniylbenzene (DVB) as a cross-linker. A clear yellow/orange colored liquid was obtained from the elemental sulfur melted at 160 degrees C and then by adding various amounts of DVB to this liquid directly via a syringe at 200 degrees C viscous reddish brown polymeric materials were obtained. The copolymers are soluble in common solvents like tetrahydrofuran, dichloromethane, and chloroform, and they can be coated on any surface as a thin film by a spray coating technique. The characterization of the materials was performed by using nuclear magnetic resonance, fourier transform infrared, and Raman spectroscopies. The morphological properties were monitored via scanning electron microscope technique. Thermal analysis showed that an increase in the amount of DVB in the copolymers resulted in an increase in the thermal decomposition temperature. On the other hand, poly(S-r-DVB) copolymers exhibited good percent transmittance as 50% T between 1500 and 13,000 nm in electromagnetic radiation spectrum, which makes them good candidates to be amenable use in military and surveillance cameras. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43655.