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Öğe Active control of quarter-car and bridge vibrations using the sliding mode control(Gazi Univ, Fac Engineering Architecture, 2022) Eroglu, Mustafa; Koc, Mehmet Akif; Kozan, Recep; Esen, IsmailPurpose: The aim of this study is to model the active suspension system using conventional PID and sliding mode control, which is a robust control method, in order to increase the road holding and passenger comfort (Figure A). Theory and Methods: The equations of motion of the 3-degree-of-freedom quarter-car and bridge model examined in this study were obtained by the Lagrangian method. A total of 7 second-order differential equations were obtained, including 3 equations of motion of the car and 4 equations of motion of the bridge beam. These equations are reduced to 14 first-order differential equations with the help of state space forms. Then, the Runge-Kutta method was used to solve these equations. The dynamic responses of the quarter car while passing over the bridge were analyzed with the commercial analysis program MATLAB. Results: As a result of the study, it was understood that the displacement and acceleration values of the passenger seat take their maximum values at the critical speeds of the car-bridge and car-road system. In addition, it is understood that the dynamic responses acting on the car change at some speed value of the car according to the profile of the road. Conclusion: In this study, the vertical displacement and acceleration of the passenger seat were controlled using conventional PID and sliding mode control. In addition, the dynamic interaction between the any flexible foundation and the multi-degree-of-freedom car model can be examined in more detail by using the controllers and solution method used in this study.Öğe Application of magnetic field to reduce the forced response of steel bridges to high speed train(Pergamon-Elsevier Science Ltd, 2023) Eroglu, Mustafa; Koc, Mehmet Akif; Esen, IsmailThis paper uses a train-track-bridge interaction system to assess the dynamic performance of railway bridges exposed to a high-speed train and magnetic field. A 24 degrees of freedom 3D train model and thin steel bridge beam are considered. In the interaction of train and bridge, a new six-parameter track system consisting of rail, sleeper, and ballast is modeled. The governing equations of the bridge, track and train motions are derived based on the Lagrange method. The Lorentz force induced by the directed magnetic field in the axial direction is obtained by Maxwell's equation. Using state-space forms, the second-order equations of motion are transformed into first -order differential equations, which are then solved using the Runge-Kutta method. Studies using parametric data are done to show how the suggested approach may be used to investigate the dynamic interaction of the entire system. The magnetic field intensities and moving train speed on the interaction of the railway bridge system were investigated and analyzed for the first time in the literature. Depending on the speed of the vehicle, when the dimensionless magnetic field is Hmx=30, it can be seen that the train body's vertical displacement falls by around 50%. The obtained results are helpful for the design of railway bridges and the safe and comfortable ride of high-speed trains over flexible structures.Öğe Dynamic analysis of gun barrel vibrations due to effect of an unbalanced projectile considering 2-D transverse displacements of barrel tip using a 3-D element technique(Latin Amer J Solids Structures, 2018) Koc, Mehmet Akif; Esen, Ismail; Cay, YusufIn this paper, dynamic analysis of two different weapon systems (35 mm Anti-Aircraft Barrel (AAB) and 120 mm Grooved Tank Barrel (GTB)) under the effect of statically unbalanced projectile has been performed with a new 12 DOF 3-D element technique using Finite Element Method (FEM). The muzzle deviations, which negatively affect the barrel shooting accuracy at firing, are calculated in a time dependent manner using Newmark beta algorithm with high accuracy at both axes (yand z) considering the Coriolis centripedal and centrifugal forces. The effect of such fundamental physical parameters as shift from rotating center and angular velocity belonging to the unbalanced projectile on barrel dynamics are analyzed with this new and affective FEM. As a result, it was found out that 1% of a millimeter shift from projectile belonging to a weapon system leads to excessive vibration on both axes and compromises the shooting accuracy of the barrel.Öğe Dynamic analysis of high-speed train moving on perforated Timoshenko and Euler-Bernoulli beams(Springer Heidelberg, 2022) Koc, Mehmet Akif; Eroglu, Mustafa; Esen, IsmailThis study investigates the numerical simulation of the interaction between a high-speed train and perforated beams. The perforated bridge beam is modeled according to Timoshenko and Euler-Bernoulli beam theories with a uniform cross-section area. The high-speed dynamic model has been considered a 10-DOF multibody system. The equation of motion perforated bridge beam and high-speed train is obtained by Hamilton's principle. Then, some parameters of the perforated beam, such as different aspect ratios, the filling ratio, and the number of holes along the cross-section area, have been investigated. The frequency variation of the Timoshenko perforated beam has been evaluated according to the nondimensional parameter presented in the study, considering different filling and aspect ratios properties. Then, the mass comparison of the perforated beam with a fully solid beam has been conducted as a dynamical and statical comparison. With this method, the dynamic responses of perforated beams will be examined for the first time compared to the fully solid bridges used in previous studies in the literature. Per length mass of the perforated beam is less than the fully solid beam by the ratios of %41.51 and %30.07 in terms of dynamic and static behavior. Consequently, it has been observed that the perforated beam affects both bridge dynamic and high-speed train's dynamic.Öğe Dynamic response of a 120 mm smoothbore tank barrel during horizontal and inclined firing positions(Latin Amer J Solids Structures, 2015) Esen, Ismail; Koc, Mehmet AkifIn this study, the dynamic interaction between a 120 mm smoothbore tank barrel modeled as an Euler-Bernoulli cantilever beam and an accelerating projectile during firing is presented. The interaction was modelled using a new FEM approach that took into account the projectile's inertia, Coriolis, and centripetal forces and the horizontal and inclined positions of the barrel. The mass, exit velocity and acceleration effects of the projectile on the dynamics of the barrel were investigated. The effects of the projectile's inertia, and Coriolis and centripetal forces were evaluated as well. Furthermore, the tip displacements at different firing angles were determined by transferring the mass, stiffness and damping matrices of the barrel with the addition of the instantaneous property matrices of the projectile from a local coordinate to the global Cartesian coordinate with the aid of transformation matrices. Finally, the barrel vibrations caused by the successive firings were evaluated under different firing scenarios. To demonstrate the validity of the current study, comparisons were made with the results of previous studies and a good agreement was achieved. By using the method recommended in this study, it is possible to determine the accurate dynamic behavior of any barrel with sufficient sensitivity, without any costly or time-consuming tests being necessary.Öğe Effect of Functionally Graded Carbon Nanotube Reinforcement on the Dynamic Response of Composite Beams Subjected to a Moving Charge(Springer Heidelberg, 2024) Esen, Ismail; Koc, Mehmet Akif; Eroglu, MustafaPurposeThis article examines the forced vibrations of composite beams that have been reinforced with single-walled carbon nanotubes (SWCNTs) and subjected to a moving charge without considering the effect of mass inertia.MethodsThis study investigates three different beams, namely uniform distribution carbon nanotubes (UD-CNT), functionally graded Lambda distribution carbon nanotubes (FG Lambda-CNT), and functionally graded X distribution carbon nanotubes (FGX-CNT). The SWCNTs exhibit length alignment along the axial direction, while their volume distributions are observed in the thickness direction. The motion equations of beams are derived using Hamilton's principle and mass interaction forces based on a sinusoidal third-order shear deformation theory (TSDT). These equations are then converted into a single equation set and solved using Navier's method.ResultsThis study presents comprehensive findings on the effects of total volume fraction and distribution types of carbon nanotubes (CNTs) on the forced vibration of a composite beam caused by a moving charge at different mass velocities. The FGX-CNT distribution of the beam has demonstrated increased resistance to the dynamic impact of live load.ConclusionThe study's findings will aid in the development of micro-sensors that carry moving charges.Öğe Effect of the magnetic field on the thermomechanical flexural wave propagation of embedded sandwich nanobeams(Taylor & Francis Inc, 2024) Eroglu, Mustafa; Esen, Ismail; Koc, Mehmet AkifThis work examines thermo-mechanical bending wave propagation in a sandwich nanobeam using advanced sandwich nanobeam and nanolocal strain gradient elasticity theories. The sandwich nanobeam is a unique structure with biocompatible ceramic ZrO2 and metal Ti6Al4V on the top and bottom sides. Sandwich nanobeam cores have functionally graded materials. This combination gives the nanobeam distinctive qualities and opens up many uses in diverse industries. The wave propagation equation is computed by applying the Navier method to the medium's thermal, Lorentz, and viscoelastic equations of motion. The sandwich nanobeam is analyzed using four distinct models, taking into account its composition of ceramic and metal materials. The various factors that affect sandwich nanobeam bending wave propagation have been extensively studied. In the scenario where the magnetic field intensity is Hm = 0, an increase in temperature difference causes the wave frequency of all models (except Model 2) to decrease to zero, resulting in buckling. In Model 2, the sandwich nanobeam exhibits a phase velocity of 0.43 Km/s at Delta T = 0, which subsequently decreases by similar to 9% to 0.39 km/s at Delta T = 500. These factors include the strength of the magnetic field, the impact of thermal loads, the nonlocal effect, the dimensions of the sandwich nanobeam, and the foundation's influence. The findings of this research will help build nanosensor systems that can work in aerospace applications under extreme temperatures. These findings will contribute to the optimization of the design process, ensuring the reliability and functionality of the nanosensors under severe thermal conditions.Öğe The effect of the viscoelastic support and GRPL-reinforced foam material on the thermomechanical vibration response of piezomagnetic sandwich nanosensor plates(Springer Wien, 2024) Eroglu, Mustafa; Esen, Ismail; Koc, Mehmet AkifThis paper investigates the vibration characteristics of a sandwich nanosensor plate composed of piezoelectric materials, specifically barium and cobalt, in the upper and lower layers, and a core material consisting of either ceramic (silicon nitride) or metal (stainless steel) foams reinforced with graphene (GPRL). The study utilized the novel sinosoidal higher-order deformation theory and nonlocal strain gradient elasticity theory. The equations of motion for nanosensor sandwich graphene were derived using Hamilton's principle, considering the thermal, electroelastic, and magnetostrictive characteristics of the piezomagnetic surface plates. These equations were then solved using the Navier method. The core element of the sandwich nanosensor plate can be represented using three distinct foam variants: a uniform foam model, as well as two symmetric foam models. The investigation focused on analyzing the dimensionless fundamental natural frequencies of the sandwich nanosensor plate. This analysis considered the influence of three distinct foam types, the volumetric graphene ratio, temperature variation, nonlocal parameters, porosity ratio, electric and magnetic potential, as well as spring and shear viscoelastic support. Furthermore, an analysis was conducted on the impact of the metal and ceramic composition of the central section of the sandwich nanosensor plate on its dimensionless fundamental natural frequencies. In this context, the use of ceramic as the central material results in a mean enhancement of 33% in the fundamental natural frequencies. In contrast, the incorporation of graphene into the core material results in an average enhancement of 27%. The thermomechanical vibration behavior of the nanosensor plate reveals that the presence of graphene-supported foam and a viscoelastic support structure in the core layer leads to an increase in thermal resistance. This increase is dependent on factors such as the ratio of graphene, porosity ratio of the foam, and parameters of the viscoelastic support. Metal foam or ceramic foam has been found to enhance thermal resistance when compared to solid metal or ceramic core materials. The analysis results showed that it is important to take into account the temperature-dependent thermal properties of barium and cobalt, which are piezo-electromagnetic materials, and the core layer materials ceramics and metal, as well as the graphene used to strengthen the core. The research is anticipated to generate valuable findings regarding the advancement and utilization of nanosensors, transducers, and nano-electromechanical systems engineered for operation in high-temperature environments.Öğe The effects of Casimir, van der Waals and electrostatic forces on the response of nanosensor beams(Elsevier Science Inc, 2024) Koc, Mehmet Akif; Esen, Ismail; Eroglu, MustafaThe governing equations of the nanosensor beams have been modified to account for the nonlocal strain gradient effect, which considers the impact of material microstructure to capture the size-dependent behavior of the beams accurately. Additionally, surface and Casimir forces, which result from the interaction between the nanosensor beam and its environment, are deemed to be a precise representation of the system's performance on the nanoscale. The mechanical response of nanoscale structures is significantly influenced by intermolecular forces, which encompass van der Waals interactions and are therefore considered in the analysis. The present study employs analytical and numerical techniques to examine the interdependent influence of multiple factors on the thermal vibration and buckling behavior of magneto-electro-elastic functionally graded higher-order nanosensor beams. The investigation provides essential insights into the behavior of these very complex nanosensors in a variety of operational settings, and it also adds to the improvement of their configuration and effectiveness. The findings of this work contribute to a better knowledge of the intricate behavior of nanostructures and have relevant implications for the development of high-capacity nanosensor devices in a wide variety of sectors, such as biological sensing, environmental monitoring, and structural health monitoring devices.Öğe Finite element formulation and analysis of a functionally graded Timoshenko beam subjected to an accelerating mass including inertial effects of the mass(Latin Amer J Solids Structures, 2018) Esen, Ismail; Koc, Mehmet Akif; Cay, YusufThis study describes a new finite element method that can be used to analyse transverse and axial vibrations of a Functionally Graded Material (FGM) beam under an accelerating / decelerating mass. The differential equations of the FGM beam are obtained using First-order Shear Deformation Theory (FSDT). In these equations, the interaction terms of mass inertia are derived from the second-order exact differentiation of displacement functions with respect to mass contact point. The FGM beam is made of two different materials (Steel and Alumina Al2O3), which vary in thickness with a power law. Including the effects of neutral axis shift and mass inertia, the proposed method can be used when the dynamic behaviour of the FGM Timoshenko beams is to be analysed in transverse and axial directions, depending on the interaction with the acceleration of the moving loads. After validating this work with literature studies, new investigations and fmdings are presented for both moving load and mass assumptions. In addition, the obtained results of Timoshenko Beam (TBT) and Euler Bernoulli beam theory (EBT) are compared for FGM beams with various speeds and accelerations of moving mass.Öğe Modelling and analysis of vehicle-structure-road coupled interaction considering structural flexibility, vehicle parameters and road roughness(Korean Soc Mechanical Engineers, 2017) Koc, Mehmet Akif; Esen, IsmailTo determine the dynamic forces acting on vehicle components a vehicle-structure-road interaction is considered. Coupled interaction was modelled using a flexible bridge-like thin beam structure with four and six Degree of freedom (DOF) half car models. In addition to the flexible structure, the road conditions were added to the model as random and non-random surface irregularities. A coupled equation of motion of the whole system was derived using Lagrange equations, and converted to a first-order state-space equation and then solved using the fourth-order Runge-Kutta method. Besides the dynamic forces, the effects of the vehicle speed, bridge flexibility, tire stiffness, random or non-random road irregularities on the passenger comfort are widely investigated. The results obtained were compared by several early VBI (Vehicle-bridge-interaction) studies in the literature and proved accurate with a 5 % difference.Öğe A new numerical method for analysing the interaction of a bridge structure and travelling cars due to multiple high-speed trains(Inderscience Enterprises Ltd, 2021) Koc, Mehmet Akif; Esen, Ismail; Eroglu, Mustafa; Cay, YusufDynamic interaction between a 10-DOF high-speed train model and a simply supported bridge beam is studied. The second-order coupled equations of the bridge beam and train are derived using Lagrange method. The proposed method in the study provides considerable advantage by taking 0.5% of the time needed in analysing the train-bridge interaction (TBI) previously given in the literature using the finite element method (FEM). The presented modelling that includes the dynamic forces on the train components from the interaction, is created in a manner that it may assist both train and bridge engineers. It is showed that, while moving on the bridge, the dynamic forces on the train body, front and rear bogies, wheels as well as bridge are significantly affected by the speed and mass of the train, along with the flexibility of the bridge. Effects of multiple cars are included in the modelling.Öğe Optimization of a passive vibration absorber for a barrel using the genetic algorithm(Pergamon-Elsevier Science Ltd, 2015) Esen, Ismail; Koc, Mehmet AkifThe non-linear vibrations of a barrel, induced by the interaction with a high-speed moving projectile, negatively affect the shooting accuracy of a weapon. This study presents a new method that determines the non-linear behavior of the barrel with a passive vibration absorber and optimizes the absorber using the genetic algorithm (GA). Since both the barrel geometry and its coupling with the absorber are non-linear, a new finite element method (FEM) approximation has been developed for the interaction of barrel and projectile and combined with the classical finite element method. The final coupled equation of motion of entire system has been solved by a step by step integration, and for minimum tip deflection of the barrel, a GA has been then used in order to optimize the some parameters of the absorber. The results of analyses of the proposed FEM model were compared, and a good agreement was seen with the existing literature. In another example, the FEM-GA integrated optimization procedure was also used for the optimization of a passive vibration absorber, and a more accurate result (0.5% better) was obtained when compared to the experimental study given in literature. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Realistic Modelling for Analysis of Train-Structure and Ballasted-Track Interaction for High-Speed Trains(Springer Heidelberg, 2024) Eroglu, Mustafa; Koc, Mehmet Akif; Esen, Ismail; Kozan, RecepPurposeIn this study, a new train-track-bridge interaction system (TTBIS) is modelled, and the interaction of the system is analysed to calculate the dynamic responses of the (TTBIS). Considering the lateral and vertical dynamic movements, the entire train is realistically modelled with 31 degrees of freedom.MethodsThe track system is realistically modelled as flexible rail, and the infrastructure system supporting the rail with eight parameters. So, the track system consists of flexible rail, two parameter rail pad, sleeper, ballast parameters. The bridge was modelled using thin beam theory and integrated motion equation was obtained using the Lagrange method.The analytical solution of motion equation was conducted by setting up an algorithm using the Runge-Kutta method with a specially written code.ResultsAs a result of the analyses made, the length of the bridge is 50 m or less, which does not affect the vertical movements of the train. In addition, Thanks to the track system, the dynamic responses affecting the train have been reduced. It is also understood that the vertical dynamic behavior of the train is a minimum in every four wagons.ConclusionAs the significance of this research, it was seen that bridge flexibility, natural vibration frequency, track parameters, travel speed, and the number of wagons have essential effects in terms of safe travel of high-speed-train.Öğe Thermal and Mechanical Vibration Response of Auxetic Core Sandwich Smart Nanoplate(Wiley-V C H Verlag Gmbh, 2024) Koc, Mehmet Akif; Esen, Ismail; Eroglu, MustafaThis study explores a new nanoplate design's thermal and mechanical properties, including an auxetic core with a negative Poisson ratio. The core is between face plates made of barium-cobalt, which possess magnetoelectroelastic properties. The analysis centers on the parameters theta, beta 1, and beta 2 to clarify their influence on the nanoplate's performance. The evaluations of the nanoplate's thermal, electrical, and magnetic properties showcase its remarkable versatility and sensitivity. Incorporating magnetoelectroelastic face plates improves the multifunctionality of the nanoplate, making it a highly promising option for use in smart technologies. The findings offer valuable insights into the distinctive features of auxetic core structures, significantly enhancing the comprehension of these materials. This research emphasizes the potential for creating groundbreaking applications in fields like aerospace engineering and advanced electronics, where versatile and adaptable materials play a vital role. This study contributes to the broader knowledge of auxetic materials and their practical implementation in cutting-edge technological solutions by exploring the interplay between thermal, mechanical, and magnetoelectroelastic properties. The thermal and mechanical features of a new nanoplate design with an auxetic core are examined in this work. The core is between magnetoelectroelastic barium-cobalt face plates. The investigation focuses on theta, beta 1, and beta 2 to understand their impact on nanoplate performance. The nanoplate's thermal, electrical, and magnetic capabilities demonstrate its versatility and sensitivity.image (c) 2024 WILEY-VCH GmbHÖğe Thermal vibration and buckling analysis of magneto-electro-elastic functionally graded porous higher-order nanobeams using nonlocal strain gradient theory(Springer Wien, 2024) Eroglu, Mustafa; Esen, Ismail; Koc, Mehmet AkifIn this paper, free vibration analysis and temperature-dependent buckling behavior of porous functionally graded magneto-electro-thermo-elastic material consisting of cobalt ferrite and barium titanate were modeled and analyzed. A high-order sinusoidal shear deformation theory was used to accurately model the anisotropic material behavior. The study examined the porosity role variation across thickness in the buckling and free vibration behavior of nanobeams, as well as the effects of magneto-electro-elastic coupling, thermal stresses, nonlocal properties, externally applied electric and magnetic field potential, and porosity volume fraction.Öğe Thermomechanical vibration response of nanoplates with magneto-electro-elastic face layers and functionally graded porous core using nonlocal strain gradient elasticity(Taylor & Francis Inc, 2024) Koc, Mehmet Akif; Esen, Ismail; Eroglu, MustafaThe thermal vibration and buckling behavior of a functionally graded nanoplate are examined in this study. The nanoplate is made up of a silicon nitride/stainless steel core plate and two cobalt-ferrite/barium-titanate face plates. Four alternative porosity models were used to simulate the porosity of the nanoplate, and numerous variables that can affect the nanoplate's behavior were taken into account. The study found that the thermomechanical behavior of nanoplates with magneto-electro-elastic face layers and a functionally graded porous core plate is affected by material gradation indices, porosity ratios, nonlocal variables, and different core plate material porosity models.Öğe Tip Deflection Determination of a Barrel for the Effect of an Accelerating Projectile Before Firing Using Finite Element and Artificial Neural Network Combined Algorithm(Latin Amer J Solids Structures, 2016) Koc, Mehmet Akif; Esen, Ismail; Cay, YusufFor realistic applications, design and control engineers have limited modelling options in dealing with some vibration problems that hold many nonlinearity such as non-uniform geometry, variable velocity loadings, indefinite damping cases, etc. For these reasons numerous time consuming experimental studies at high costs must be done for determining the actual behaviour such nonlinear systems. However, using advantages of multiple computational methods like Finite Element Method (FEM) together with an Artificial Intelligence (ANN), many complicated engineering problems can be handled and solved to some extent. This study, proposes a new collective method to deal with the nonlinear vibrations of the barrels in order to fulfil accurate shooting expectancy. Using known analytical methods, in practical, to determine dynamic behaviour of the barrel beam is not possible for all conditions of firing that include numerous varieties of ammunition for different purposes, and each projectile of different ammunition has different mass and exit velocity. In order to cover all cases this study proposes a new method that combines a precise FEM with ANN, and can be used for determining the exact dynamic behaviour of a barrel for some cases and then for precisely predicting the behaviour for all other possible cases of firing. In this study, the whole nonlinear behaviour of an antiaircraft barrel were obtained with 3.5% accuracy errors by ANN trained by FEM using calculated analysis results of ammunitions for a particular range. The proposed FEM-ANN combined method can be very useful for design and control engineers in design and control of barrels in order to compensate the effect of nonlinear vibrations of a barrel for achieving a higher shooting accuracy; and can reduce high-cost experimental works.Öğe Train-structure interaction for high-speed trains using a full 3D train model(Springer Heidelberg, 2022) Eroglu, Mustafa; Koc, Mehmet Akif; Esen, Ismail; Kozan, RecepIn high-speed trains, the driving safety and passenger comfort of the railway vehicle are negatively affected due to the problem of interaction between the train and the bridge. Among these problems are rail irregularities, flexible foundation effect, and external effects such as wind load and seismic loads. In this study, the dynamic interaction between the full train model modeled as 31-degrees of freedom and the bridge that can be modeled according to the Euler-Bernoulli beam theory was studied. The motion equations of the train and bridge beams have been derived with the Lagrange method, and the motion equations obtained have been solved with the fourth-degree Runge-Kutta method. The results obtained in this method were confirmed by two case studies previously conducted. The first four natural frequencies of the beam calculated using bridge parameters were determined, and the resonance velocities, which are the critical velocities of the beam-train system corresponding to this determined frequency, were calculated. Moving at resonance velocities, the train causes maximum acceleration amplitudes, especially in low damped beams. In this study, maximum dynamic responses were determined at variable velocities of the train, and it was understood that critical velocities were an essential concept in train-bridge interaction. It has also been found that well-damped beams reduce maximum dynamic responses. As a result, it was found that car body mass, bridge length, and train velocity significantly affect the combined train-bridge dynamic interaction.
