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    Design and heat analysis of basalt glass as a thermal storage material in a concentrated solar power (CSP) system
    (Springer, 2024) Gunindi, Baran; Toygar, M. Evren; Tumer, Devrim
    This study is based on a finite element analysis of a heat storage material (HSM). Before starting the analysis, heat storage model, heat storage insulation material, heat transfer fluid (HTF) and HSM have been determined. The heat storage model was designed in the CATIA V5 program in accordance with the literature data, and the material of the heat storage vessel was determined as stainless steel (AISI-304) due to its high melting point. Basalt glass, which is a type of basaltic rock, was chosen as the HSM. In this study, the average temperature of basalt glass was around 901.5 K, and heat storage was carried out with basalt glass at this average temperature. Air was chosen as an HTF because it is suitable for storage at the high temperatures. The heat insulation material was determined as ceramic fiber because it is suitable for storing heat at high temperatures. After all, the heat storage components were designed and determined in the CATIA V5 program, and the Ansys software was used for the analysis. After the analysis was performed for 6000 s in Ansys Fluent, it was observed that approximately 13.57 kWh heat was stored. In this study, we observed that basalt glass can be used as an alternative material for HSM at high temperatures for concentrated solar power technologies. The obtained results were comparatively evaluated with the previous studies, and it was concluded that the system was compatible and applicable.
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    The effects of tears in on other rotator cuff constituents
    (Elsevier, 2024) Tumer, Devrim; Arman, Yusuf; Havitcioglu, Hasan
    The rotator cuff tear effects on glenohumeral joint tissues, such as superior labrum anterior-posterior (SLAP) lesions, have been studied experimentally or numerically in various cases. In relation to these studies, and as a novel feature of our study, infraspinatus (INF) muscle tear effects on other muscle force variations and stress and strain increases on glenoid labrum (GL), glenoid cartilage (GC) tissues, and a SLAP pathology were investigated. The ITK-SNAP Software (ISS) was used to segment the humerus and glenoid bone. The surface entities were segmented and exported to SolidWorks 2019, where the finite element model (FEM) was completed. Static optimizations of the muscle forces were calculated using a generic model in OpenSim 4.1 for the 0-3.88 s time interval to perform our finite element analyses (FEAs) in ANSYS 19.3 for the intact, partial torn, and fully torn INF muscle. The FEAs were also conducted for the specified time interval. The stress and strain increases on the GL, and GC tissues were determined to be critical when compared with yield strengths. In the case of fully torn INF, the GL and cartilage interfacial principal stress was calculated to be 3.3856 MPa. In the case of the fully torn INF, the principal stress that occurred on the GC tissue was calculated to be 42.465 MPa. In the case of the intact INF, the principal stress that occurred on the labrum was obtained as 4.257 MPa. These results showed that there was no detachment or disorder on the designated tissues caused by the INF muscle tear when the shoulder functioned at 60 degrees of external rotation at 11 degrees of abduction. Nonetheless, a minor amount of external force could cause severe pathological effects on the specified tissues.
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    Investigation of effective coating of the Ti-6Al-4V alloy and 316L stainless steel with graphene or carbon nanotubes with finite element methods
    (Elsevier, 2020) Tumer, Devrim; Gungorurler, Musa; Havitcioglu, Hasan; Arman, Yusuf
    Background: The Ti-6Al-4V alloy and 316L stainless steel are widely used biocompatible implant materials for repairing bone fractures and their mechanical properties are now being considered for various other applications. Due to the mentioned reasons, we initially investigated and determined the mechanical effects of these biocompatible implant materials. in the sequel, as a novelty of this study, we adopted a unique approach to investigating these materials and sought to determine if coating the Ti-6Al-4V alloy and 316L stainless steel with graphene or carbon nanotubes (CNTs) could provide superior mechanical properties compared to when their surface is uncoated. Methods: To investigate the mechanical effects of the Ti-6Al-4V alloy and 316L stainless, finite element method was utilized. Finite element analyses (FEAs) of the Ti-6Al-4V alloy and 316L stainless steel samples were comparatively conducted with the numerical results in literature. Static structural analyses were generated for the externally fixated femur in the single-leg stance position. Comparative static load analyses were performed for six distinctive cases of the uncoated Ti-6Al-4V alloy and 316L stainless steel, and graphenecoated Ti-6Al-4V alloy, CNT-coated Ti-6Al-4V alloy, graphene-coated 316L stainless steel, and CNT-coated 316L stainless steel. Results: The results of the static load analyses of the six distinctive cases show that the uncoated Ti-6Al-4V, graphene-coated Ti-6Al-4V, and CNT-coated Ti-6Al-4V samples stress values are 48.29 MPa, 36.24 MPa, and 87.574 MPa for the femur, the first screw, and plate stresses, respectively. These stresses are the minimum stress values occurred on the femur, the first screw, and the plate, respectively. on the other hand, the graphene-coated 316L and CNT-coated 316L stainless steel samples had the minimum displacement values, which were obtained as 1.558 mm, 1.5576 mm at the femoral head, and 0.13029 mm, 0.13028 mm at the fracture line, respectively. Conclusion: The main result and conclusion of this study is that coating the Ti-6Al-4V alloy and 316L stainless steel samples with graphene or CNTs results in superior mechanical performance in comparison to when they are uncoated. Considering the FEAs of the six different materials, CNT- or graphene-coated Ti-6Al-4V and CNT- or graphene-coated 316L stainless steel are the most recommended finite element models (FEMs) in terms of stress and displacement values, respectively. By using CNT- or graphene-coated Ti-6Al-4V and CNT- or graphene-coated 316L stainless steel, more durable, stable externally fixated implants can be obtained for femoral shaft fractures in terms of stress and displacement reduction occurred on both femur and implants. (C) 2020 The Author(s). Published by Elsevier B.V.