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Conference Object Citation - Scopus: 1Numerical Modeling of Recycled Rubber Based Composites Reinforced With Glass Fibers at High Strain Rates(Springer, 2022) K-Cakir,G.; Aslan,O.; Bayraktar,E.Due to its high impact energy absorption properties, devulcanized recycled rubber based composites can be considered as a low cost candidate material for military applications which require lightweight protection against shock waves. This work aims at modeling of low cost devulcanized recycled rubber based composite behavior at high strain rates. In that framework, we established a continuum-based material model in order to capture the macroscopic behavior of the recycled rubber based composite material and numerically reproduce the results from the basic characterization tests. The model is implemented for Finite Element Analysis Software ABAQUS/Standard as a user subroutine UMAT for implicit nonlinear finite element calculations in order to simulate the behavior of several RVEs representing the microstructure of the composite and it is behavior at high strain rates. © 2022, The Society for Experimental Mechanics.Article Citation - WoS: 13Citation - Scopus: 16Nonisothermal Warm Deep Drawing of Ss304: Fe Modeling and Experiments Using Servo Press(Springer London Ltd, 2016) Kaya, SerhatExperimental and viscoplastic finite element analysis (FEA) of thermo-mechanical plastic deformation in nonisothermal warm deep drawing is studied using SS304. A nonisothermal deep drawing tool is used in a servo-motor-controlled press. Drawability window of SS304 under elevated temperatures (25-225 A degrees C) and low to high strain rates (drawing speeds of 2.5, 25, and 50 mm/s) were determined. A viscoplastic thermal material model is adopted for nonwork softening material behaviors, as seen in low-temperature forming of SS304, and found to be easily applicable and quite satisfactory. Tensile and equi-biaxial bulge tests were conducted for more accurate flow stress data to be used in FEA. Measured punch load-stroke and cup's curvilinear thickness (rolling/transverse) curves were successfully compared with predictions from the nonisothermal FE model of the warm deep drawing.Conference Object Analysis of Force-Indentation Measurements on Anisotropic Metals(Edizioni libreria progetto, 2005) Koray,E.; Topcu,N.; Tekkaya,A.E.Indentation tests are widely used with simultaneous measurements of indentation depth and force especially for determining material properties. In this study, findings on parameters affecting the force-displacement curves obtained from indentations on anisotropic metals using special not self-similar indenters will be presented. Parameters such as specimen dimensions, friction, surface roughness, specimen clamping and indentation spacing have been investigated by finite element analysis and by experiments. Optimum values of these parameters to achieve higher repeatability and accuracy are determined.Article Citation - WoS: 6Citation - Scopus: 8Finite Element Analysis of Fgm Dental Crowns Using Phase-Field Approach(Elsevier, 2023) Sait, Ferit; Saeidi, Nazanin; Korkmaz, TuranFunctionally graded materials (FGMs) - categorized in advanced composite materials - are specially designed to reduce the stresses and failure due to material mismatches. Advances in manufacturing techniques have brought FGMs into use in a variety of applications. However, the numerical analysis is still challenging due to the difficulties in simulations of non-homogeneous material domains of complex parts. Presenting a numerical procedure that both facilitates the implementation of material non-homogeneity in geometrically complex mediums, and increases the accuracy of the calculations using a phase-field approach, this study investigates the usage of FGMs in dental prostheses. For this purpose, a porcelain fused to metal (PFM) mandibular first molar FGM crown is simulated and analyzed under the maximum masticatory bite force, and eventually the results are compared to a PFM crown prepared conventionally.Article Citation - WoS: 55Biomechanical Comparison of Implant Retained Fixed Partial Dentures With Fiber Reinforced Composite Versus Conventional Metal Frameworks: a 3d Fea Study(Elsevier, 2011) Erkmen, Erkan; Meric, Gokce; Kurt, Ahmet; Tunc, Yahya; Eser, AtilimFiber reinforced composite (FRC) materials have been successfully used in a variety of commercial applications. These materials have also been widely used in dentistry. The use of fiber composite technology in implant prostheses has been previously presented, since they may solve many problems associated with metal alloy frameworks such as corrosion, complexity of fabrication and high cost. The hypothesis of this study was that an FRC framework with lower flexural modulus provides more even stress distribution throughout the implant retained fixed partial dentures (FPDs) than a metal framework does. A 3-dimensional finite element analysis was conducted to evaluate the stress distribution in bone, implant-abutment complex and prosthetic structures. Hence, two distinctly different models of implant retained 3-unit fixed partial dentures, composed of Cr-Co and porcelain (M-FPD model) or FRC and particulate composite (FRC-FPD model) were utilized. In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal forces were simulated. When the FRC-FPD and M-FPD models were compared, it was found that all investigated stress values in the M-FPD model were higher than the values in the FRC-FPD model except for the stress values in the implant-abutment complex. It can be concluded that the implant supported FRC-FPD could eliminate the excessive stresses in the bone-implant interface and maintain normal physiological loading of the surrounding bone, therefore minimizing the risk of peri-implant bone loss due to stress-shielding. (C) 2010 Elsevier Ltd. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 2Performance of a Prestressed Concrete Pedestrian Bridge System Under Equivalent Static Lateral Impact Loads(Asce-amer Soc Civil Engineers, 2013) Baran, Eray; Schultz, Arturo E.; French, Catherine E.The resistance of prestressed concrete through-girder (PCTG) pedestrian bridges to lateral loads was studied in response to the increasing number of vehicular impacts in the United States. This research was motivated by the lack of reported studies analyzing the behavior of such bridges to lateral impact loads, as well as their potential vulnerability in comparison with bridges that are better able to redistribute and transfer locally applied impact loads through alternate load paths. Pedestrian bridges are of lighter construction than highway bridges and they do not have the high degree of redundancy, making them more vulnerable to collapse in the event of vehicular impact. Results from static lateral load analyses using three-dimensional, geometrically nonlinear, full-scale finite element (FE) models of a typical bridge system and bridge subassemblages were used to evaluate the characteristics of the system. The FE models were calibrated with experimental test data on typical subassemblages and connection details for PCTG bridges. Results of the experimental part of the program have already been published elsewhere. This paper summarizes the observations obtained from nonlinear static FE analyses of a PCTG pedestrian bridge system subjected to lateral impact loads. The analyses indicated that the location of impact, the type of connector, and the flexibility of the end support details affected bridge performance. Improved connection details are suggested for enhanced PCTG pedestrian bridge performance.Article Citation - WoS: 38Citation - Scopus: 43Experimental and Numerical Analysis of a Bolted Connection in Steel Transmission Towers(Elsevier Sci Ltd, 2016) Baran, Eray; Akis, Toga; Sen, Gokmen; Draisawi, AmmarThis paper presents an integrated numerical and experimental study on a bolted splice connection used in main legs of steel lattice transmission towers. At specific locations, where the number of angle sections in built-up cross section of main leg members changes, the complex geometry around the connection region results in eccentricities in the load path and indirect load transfer. Such complex configurations and uncertainties in the load path have led to overdesigned connections with increased number of bolts and redundant connection reinforcing members. The current study was conducted in an attempt to gain a better understanding of the load-flow mechanism at this specific location where the cross section of main leg members changes. The experimental part included tensile load testing of six specimens with different connection details. The main parameters used in the testing program were the number of bolts used in the connection as well as the presence of connection reinforcement angles and tie plate. For all connection configurations studied, the failure occurred due to net section fracture of upper main member angle near leading bolt holes. The calculated load capacity based on the measured material strength closely predicted the measured load capacity of specimens. The experimentally determined response of each connection configuration was better predicted by the FE model that incorporates bolt slip as compared to the model that assumes no slip. The experimental and numerical results also indicate that major differences among the investigated connection details do not cause any appreciable difference in behavior under tensile loading. (C) 2016 Elsevier Ltd. All rights reserved.Article Citation - WoS: 14Citation - Scopus: 15A New Axial Flux Permanent Magnet Synchronous Alternator Autonomously Adapted To Wind Speeds(Elsevier Sci Ltd, 2015) Kalender, Osman; Ege, Yavuz; Eskidere, Omer; Karen, Idris; Gurdal, Osman; Unal, Cevat; Kabadayi, MuratIn this study, a new axial flux permanent magnet synchronous generator (PMSA) design and prototyping procedures are presented. It is composed of a stack of rotor-stator blocks on the same shaft. In other words, it is made up of four alternators based on axial flux permanent magnets that can generate electrical energy within the limits of rotor rotational speed with varying wind speeds. A control system is also introduced to the generator. The control system connects or disconnects the stator blocks to the load according to the changing speeds of the wind. It produces electrical energy with stable voltage, frequency and variable power at the output. The efficiency of the generator is tested with different load and speed conditions. It is observed that the efficiency is high when the speed is low in case the load is connected only one stator. The efficiency is high when the speed is above 200 rpm for the case where several stators are connected to the load. It can be seen that the incremental structure of the generator is suitable for changing speeds of the wind. It can have high efficiency for both low and high speeds with changing the number of stator blocks connected to the load. (C) 2015 Elsevier Ltd. All rights reserved.
