WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object Investigation of Nanoscale Droplet Evaporation by Molecular Dynamics Simulations(Begell House, inc, 2022) Satiroglu, Ezgi; Barisik, MuratHeat transfer by boiling is promising for future thermal management problems. The phase change during boiling condition is interrupted by a vapor layer forming between the liquid and solid, which is called as the Leidenfrost phenomena. Leidenfrost develops strongly depending on the solid/liquid coupling at the interface. For such a case, we studied evaporation behavior of water droplets at nanoscale under varying wetting conditions in order to characterize the Leidenfrost effects. While the experimental analysis is challenging, we employed Molecular Dynamics simulations of water droplets over silica surfaces to investigate Leidenfrost at nanoscale. As a continuation of our earlier work on size dependent influence of contact line pinning on wetting of nano-textured/patterned silica surfaces. Evaporation of the different size droplets were simulated over silica surfaces with different nanopatterns. We observed that the thermal transport at the solid-liquid interface showed strong dependence on surface wetting and Leidenfrost temperature. Specifically, a sudden increase in the interface thermal resistance was observed when the droplet temperature reached to the Leidenfrost point, and the heat transfer decreased significantly. Increasing the size of the surface structures pushed the Leidenfrost point to higher surface temperatures.Article Citation - WoS: 7Citation - Scopus: 7Improving Mechanical Behavior of Adhesively Bonded Composite Joints by Incorporating Reduced Graphene Oxide Added Polyamide 6,6 Electrospun Nanofibers(Elsevier Sci Ltd, 2024) Yeke, Melisa; Barisik, Murat; Tanoglu, Metin; Ulas, M. Erdal; Nuhogu, Kaan; Esenoglu, Gozde; Iris, M. ErdemAdhesive joining of fiber-reinforced polymer (FRP) composites requires adequate interface tailoring and careful surface preparation to obtain a strong bond between components. This study aimed to improve the mechanical performance of adhesively bonded unidirectional carbon fiber-based (CFRP) composite parts by modifying joint surfaces with graphene-added electrospun Polyamide 6,6 (PA66) nanofibers. Reduced graphene oxide (rGO) was dispersed at 10 % wt/v PA66 solution at three different concentrations below rGO saturation limits. Bead-free nanofibers with homogenous graphene distribution were obtained on a prepreg by electrospinning. Addition of up to 2 % rGO yielded complete dispersion through the nanofiber network while the higher values created local agglomerations. Surface wetting experiments showed conversion of slightly hydrophobic surfaces to complete hydrophilic with electrospun nanofiber coating and the lowest contact angle was obtained at 2 % wt/v rGO addition (26.18 degrees +/- 2.03 degrees). Composite plates were produced in a hot press keeping the modified prepregs on top. Plates with different surface treatments joined by secondary bonding using 3 plies of FM 300 K film adhesive. Mechanical properties of adhesively bonded composites were tested by Single lap joint and Charpy impact tests. We achieved an 18 % increase in shear strength and 31 % increase in impact strength by adding 2 % wt/v ratio rGO into PA66 electrospun nanofiber.