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Öğe An investigation of plastic deformation behaviour of Nb-V microalloyed steel produced by powder metallurgy(National Library of Serbia, 2024-10) D. Taştemür; S. GündüzIn this study, microalloyed Nb-V steel was produced and sintered at 1150 °C for 1 h followed by cooling in furnace. While one of the sintered samples was used in the sintered state, the other was air cooled at 1150 °C for 1 hour after homogenization heat treatment. The remaining samples were deformed at 20%, 40% and 60% in the temperature range of 1150–930 °C and then cooled in air. The microstructure and the formation of precipitates in the samples were investigated using an optic microscope, scanning electron microscope and energy dispersive spectroscopy analyses. It was found that the samples under homogenized and 20%, 40% or 60% deformed conditions had a smaller grain size but higher volume fractions of ferrite. This indicates that grain refinement and ferrite formation are accelerated by the deformation which affects the nucleation rate of the ferrite. The yield strength, hardness and density also increased with increasing deformation rate.Öğe Multiplanar Semicircular New-Generation Implant System Developed for Proximal Femur Periprosthetic Fractures: A Biomechanical Study.(Multidisciplinary Digital Publishing Institute (MDPI), 2025-01-14) Satılmış, Ahmet Burak; Ülker, Ahmet; Uzunay, Zafer; Cengiz, Tolgahan; Temiz, Abdurrahim; Yaşar, Mustafa; Mutlu, Tansel; Daşar, UygarThe study aimed to evaluate a newly designed semicircular implant for the fixation of Vancouver Type B1 periprosthetic femoral fractures (PFFs) in total hip arthroplasty (THA) patients. To determine its strength and clinical applicability, the new implant was compared biomechanically with conventional fixation methods, such as lateral locking plate fixation and a plate combined with cerclage wires. : Fifteen synthetic femur models were used in this biomechanical study. A Vancouver Type B1 periprosthetic fracture was simulated by osteotomy 5 mm distal to the femoral stem. The models were divided into three groups: Group I (lateral locking plate fixation), Group II (lateral locking plate with cerclage wires), and Group III (new semicircular implant system). All fixation methods were subjected to axial loading, lateral bending, and torsional force testing using an MTS biomechanical testing device. Failure load and displacement were measured to assess stability. : The semicircular implant (Group III) demonstrated a significantly higher failure load (778.8 ± 74.089 N) compared to the lateral plate (Group I: 467 ± 68.165 N) and plate with cerclage wires (Group II: 652.4 ± 65.474 N; < 0.001). The new implant also exhibited superior stability under axial, lateral bending, and torsional forces. The failure load for Group III was more robust, with fractures occurring at the screw level rather than plate or screw detachment. : Compared to traditional fixation methods, the newly designed semicircular implant demonstrated superior biomechanical performance in stabilizing Vancouver Type B1 periprosthetic femoral fractures. It withstood higher physiological loads, offered better structural stability, and could be an alternative to existing fixation systems in clinical practice. Further studies, including cadaveric and in vivo trials, are recommended to confirm these results and assess the long-term clinical outcomes.Öğe Effect of heat treatment on interface characteristics and mechanical properties of explosive welded Cu/Ti composites(Walter de Gruyter GmbH, 2024-12-09) Yıldırım, Mehmet Serkan; Kaya, YakupCopper and titanium plates were used in the studies. Explosive welding (EW) processes were carried out using different explosive rates. The resulting composite plates were heat treated at different temperatures. Various tests were then carried out on samples with and nonheat treatment. In the SEM studies, it was observed that a flat interface shape was formed in the joints where the lowest explosive rate (R = 2.5) was used, but as the explosive rate increased, the interface shape became wavy. It was also found that a thickening diffusion layer formed as the heat treatment temperature increased. As a result of XRD and EDS analyses, it was found that Cu4Ti, CuTi2, CuTi, CuTi3, Cu3Ti2, and Cu4Ti3 intermetallic phases could be formed because of the high explosive rate and heat treatment applications. Increasing the amount of explosives increased the tensile-shear strength. However, the heat treatment applied reduced the strength values. No defects were detected in the bending tests performed on all heat-Treated and nonheat-Treated samples.Öğe Estimating the crashworthiness performances of crushboxes using artificial neural network(Wiley, 2024-12-20) Koçar, O.; Adanur, Ö.; Varol, F.; Guldibi, A. S.Studies on the development of energy absorbing systems that minimize vehicle chassis damage in traffic accidents are increasing day by day. Many designs have been made in the studies on crushboxes used to absorb the energy released in the event of an accident. These design works are quite costly and take a long time. In this study, to design crushboxes faster and more economically was estimated using artificial neural network. The input layer of the artificial neural network model consists of three different materials, thicknesses (between 0.8 and 2.2 mm) and three different initial speeds. In the artificial neural network model, 42 different models were created by changing the different training functions (training, trainlm and trainrp), transfer functions (tansig and logsig) and the number of neurons in the hidden layer (between 9 and 33). R2 and root mean square error (RMSE) methods were used to evaluate the efficiency of artificial neural network models. The training function was found to be highly accurate (R2: 0.99999 and root mean square error: 0.314727E-05) when the training function was “trainlm” and the number of neurons in the hidden layer was 33. The training and testing results of the artificial neural network model show that artificial neural networks can be used to estimate the specific energy absorption/energy/peak crush force value of crushboxes.Öğe A multi-scale analysis to predict elastic response in different weight fractions of carbon fiber powder(Springer Nature, 2024-11-29) Öztürk, Fatih HuzeyfeIn this study, the effect of varying weight percentages of carbon fiber powder (CFP) (10 wt.%, 20 wt.% and 30 wt.%) on the mechanical properties of polycarbonate (PC) components produced by plastic injection molding was investigated using analytical, numerical and experimental methods. This research is a novel study in terms of comparing experimental data with microscopic features and full-scale analysis. The micro-scale study was carried out using the Halpin-Tsai (HT) and Generalized Modified Halpin Tsai (G-HT) models as well as the representative volume element (RVE). Findings from RVE were then transferred to the finite element analysis (FEA) module for full-scale comprehensive analysis. A comparison of the experimental tensile test results demonstrated an increase of 56.90% and 191.47% in the tensile strength and Young’s modulus of the composite containing 30 wt. % CFP compared to pure PC, respectively. The minimum and maximum differences between Young’s modulus and the experimental Young’s modulus were determined to be 0.39% and 7.92% using RVE and G-HT, respectively. The maximum and minimum value of the difference between experimental and FEA strengths were determined as 3.44% and 1.91%, respectively. Young’s modulus of the composite with increasing fiber weight ratio was successfully predicted by RVE, G-HT and FEA.Öğe Predictive fault detection and resolution using YOLOv8 segmentation model: A comprehensive study on hotspot faults and generalization challenges in computer vision(Ain Shams University, 2024-12-01) Shamta, Ibrahim; Demir, Funda; Demir, Batıkan ErdemPhotovoltaic systems are considered the cornerstone of renewable energy, with rapidly increasing use and large-scale fields, there are significant limitations that affect their efficiency. This study presents the imperative necessity of promptly predicting failures to mitigate their adverse effects on performance with photovoltaic systems. Through an exploration of the most prevalent faults, their impacts, and cutting-edge solutions, this research contributes to the understanding and management of system failures. Furthermore, the study implements the YOLOv8 segmentation model to detect a specific type of fault known as a hotspot fault. The findings include a comprehensive examination of the results, incorporating data augmentation techniques, and assessing their influence on the overarching challenge of generalization in computer vision. This investigation not only enriches the discourse surrounding fault prediction but also offers insights into enhancing the robustness and reliability of fault detection methodologies.Öğe Fabrication and characterization of a new high-strength alloy via WAAM using GMAW+cold wire feeding(Elsevier, 2024-12-01) Ayan, YusufThe demand for high-strength steels has continued to increase in various fields of industry due to the advancement in technology. The wire arc additive manufacturing (WAAM) enables the fabrication of high-strength structures from different materials by controlling the raw wire in layers. This study focuses on the fabrication of high-strength steel by WAAM using the gas metal arc welding + cold wire feeding (GMAW + CWF) technique. A new alloy was formed by simultaneously adding 316LSi stainless steel from the CWF to the low alloyed ER70S-6 steel from the GMAW torch. In this way, three different new alloyed structures were produced with varied 316LSi ratios ranging from 10 %, 20 % and 25 % respectively. Besides, their metallurgical and mechanical properties were compared with each other and with single material WAAMed structures. In the macrostructure examinations, no defects due to the mixture of both materials were found and both materials melted properly to create the new alloy. Due to the alloying elements transferred from 316LSi, the microstructure of the new material parts were completely changed compared to the single material WAAMed components and bainite and martensite phases were found in the new alloys. The hardness increased significantly compared to the single-material WAAMed structures and increased up to 139 % and 84 % compared to the single-material WAAMed ER70S-6 and 316LSi, respectively. The tensile strength showed a great improvement and reached almost 1200 MPa, increased by 142 % compared to the single-material WAAMed structure. The fabricated new alloys have the potential to be a candidate material for industries that use high-strength steel.
