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ŞENDUR, Polat

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Now showing 1 - 10 of 44
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    Multi-strategy Gaussian Harris hawks optimization for fatigue life of tapered roller bearings
    (Springer, 2022-12) Abbasi, Ahmad; Firoozi, Behnam; Şendur, Polat; Heidari, A. A.; Tiwari, R.; Mechanical Engineering; ŞENDUR, Polat; Abbasi, Ahmad; Firoozi, Behnam
    Bearing is one of the most fundamental components of rotary machinery, and its fatigue life is a crucial factor in designing. The design optimization of tapered roller bearing (TRB) is a complex design problem because various arrays of designing parameters and functional requirements should be fulfilled. Since there are many design variables and nonlinear constraints, presenting an optimal design of TRBs poses some challenges for metaheuristic algorithms. The Harris hawks optimization (HHO) algorithm is a robust nature-inspired method with unique exploitation and exploration phases due to its time-varying structure. However, this metaheuristic algorithm may still converge to local optima for more challenging problems such as the design of TRBs. Therefore, this study aims to improve the accuracy and efficiency of the shortcomings of this algorithm. The performance of the proposed algorithm is first evaluated for the TRB optimization problem. The TRB optimization design has nine design variables and 26 constraints because of geometrical dimensions and strength conditions. The productivity of the proposed method is compared with diverse metaheuristic algorithms in the literature. The results demonstrate the significant development of dynamic load capacity in comparison to the standard value. Furthermore, the enhanced version of the HHO algorithm presented in this study is benchmarked with various well-known engineering problems. For supplementary materials regarding algorithms in this research, readers can refer to https://aliasgharheidari.com.
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    Computational and experimental investigation of vibration characteristics of variable unit-cell gyroid structures
    (International Center for Numerical Methods in Engineering, 2019) Şimşek, Uğur; Gayir, C.; Kavas, B.; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat; Şimşek, Uğur
    Triply periodic minimal surface (TPMS) based geometries exhibit extraordinary mechanical, thermal, electrical and acoustic properties thanks to their unique topologies. There are various types of structures in the TPMS family. One of the most well-known TPMS structures is the gyroid structure. This paper focuses on the vibrational behavior of a novel sandwiched gyroid structure in terms of their natural frequencies and mode shapes with three different feasible unit sizes at same volume ratio. Powder bed fusion technology is employed to fabricate gyroid porous specimens made of HS188 material. Modal testing is performed to deduce the vibration characteristics of aforementioned cellular structures. Besides the experimental study, the dynamic performance of the considered structures is investigated computationally by performing modal analysis using Finite Element (FE) models. A key challenge facing FE modelling of large scale gyroid structure is computation time and accuracy. For that reason, small size of gyroid lattices are utilized for compression tests in order to extract elastic properties. Then sandwiched gyroid plate is modelled as solid body with calculated elastic properties instead of complex gyroid topology and analyzed. Finally correlation level between experimental and FE results are presented.
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    Topology optimization of an anti roll bar of a heavy commercial truck for vehicle dynamics and durability
    (The American Society of Mechanical Engineers, 2019) Yenilmez, Ece; Yaşar, Ali; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat; Yenilmez, Ece; Yaşar, Ali
    Meeting the stringent requirements on fuel economy and emissions is still a challenge for automotive original equipment manufacturers (OEMs). In this study, we consider the light weighting opportunities of a heavy commercial truck by evaluating the various requirements of its anti-roll bar. First, an MSC.ADAMS model of the truck is analyzed under some standard vehicle dynamics maneuvers and a target for the anti roll bar is set. A topology optimization study is then performed using Solid Isotropic Material with Penalization (SIMP) method to determine its dimensions and material to meet this target. For this purpose, a finite element (FE) model of the anti-roll bar is developed in order to determine its torsional stiffness using MSC.Nastran commercial software. The advantages and disadvantages of various optimization results are discussed. Finally, fatigue performance of the anti-roll bar is assessed under the road load data coming from various road simulations. The results prove that the simulation tools and optimization methods offer great capabilities to meet challenging requirements of automotive industry.
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    Topology optimization of constrained and unconstrained damping layers
    (Canadian Acoustical Association, 2019) Mansouri, Deniz; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat; Mansouri, Deniz
    Damping is an effective way of suppressing mechanical vibrations. Passive constrained and unconstrained layer damping patches are often used in the industry as damping solution for vibrations and acoustics problems. In this study, topology optimization methods were applied to the finite element models (FEM) of plates and damping patches in order to determine the critical locations for the frequency range of interest. For that purpose, MSC. Nastran SOL 200 optimization is used for both topology and thickness optimization. The structures are excited at single point and the acceleration of the plate at a pre-determined location is considered as output. The objective of the optimization is chosen as the minimization of the acceleration spectrum up to 500 Hz. The optimized damping patch topology is compared to the base plate with full application of damping patch on frequency response functions. The simulation results from topology and thickness optimization show that these methods can effectively improve the frequency response functions.
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    The effect of interlaminar graphene nano-sheets reinforced e-glass fiber/ epoxy on low velocity impact response of a composite plate
    (IOP Publishing, 2018-05) Al-Maharma, Ahmad Yousef Mohammad; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat; Al-Maharma, Ahmad Yousef Mohammad
    In this study, we compare the inter-laminar effect of graphene nano-sheets (GNSs) and CNTs on the single and multiple dynamic impact response of E-glass fiber reinforced epoxy composite (GFEP). In the comparisons, raw GFEP composite is used as baseline for quantifying the improvement on the dynamic impact response. For that purpose, finite element based models are developed for GNSs on GFEP, graphene coating on glass fibers, inter-laminar composite of CNTs reinforced polyester at 7.5 vol%, and combinations of all these reinforcements. Comparisons are made on three metrics: (i) total deformation, (ii) the contact force, and (iii) internal energy of the composite plate. The improvement on axial modulus (E1) of GFEP reinforced with one layer of GNS (0.5 wt%) without polyester at lamination sequence of [0]8 is 29.4%, which is very close to the improvement of 31% on storage modulus for multi-layer graphene with 0.5 wt% reinforced E-glass/epoxy composite at room temperature. Using three GNSs (1.5 wt%) reinforced polyester composite as interlaminar layer results in an improvement of 57.1% on E1 of GFEP composite. The simulation results reveal that the interlaminar three GNSs/polyester composite at mid-plane of GFEP laminated composite can significantly improve the dynamic impact resistance of GFEP structure compared to the other aforementioned structural reinforcements. Reinforcing GFEP composite with three layers of GNSs/polyester composite at mid-plane results in an average of 35% improvement on the dynamic impact resistance for healthy and damaged composite plate under low velocity impacts of single and multiple steel projectiles. This model can find application in various areas including structural health monitoring, fire retardant composite, and manufacturing of high strength and lightweight mechanical parts such as gas tank, aircraft wings and wind turbine blades.
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    Simplified transfer function approach for modeling frequency dependency of damping characteristics of rubber bushings
    (Sage, 2019-09) Aydemir, E.; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat
    Physical systems that consist of parts and vibration isolators such as rubber bushings are usually modeled in multibody simulations, where parts are represented as rigid bodies with their mass and inertia properties and rubber bushings are modeled with Voigt models to represent their stiffness and damping characteristics. Employment of Voigt models in multi-degree-of-freedom systems, however, may result in lower accuracy due to limitations in representing frequency-dependent dynamic characteristics of vibration isolators. To overcome this challenge, in this study, we develop and present a simplified frequency-dependent transfer function model by generating their frequency-dependent complex stiffness and damping from vehicle-level measurements. The damping characteristics of rubber bushings as a function of frequency is represented by a second-order transfer function. Three parameters of the transfer function are determined by solving an optimization problem to minimize the integral of absolute error between the measurement and simplified model's predictions. Sequential Quadratic Programming, a gradient descent-based algorithm, is selected as the optimization algorithm for this purpose. The proposed methodology is demonstrated on a heavy commercial truck. Truck cabin is represented as a rigid body connected to four rubber bushings, which are modeled to show the frequency dependency of the damping as a simple transfer function. Simulation results are well correlated with the measurements obtained from prototype vehicle tests on various road profiles showing capability improvement over Voigt modeling approach due to a more representative damping characteristic of rubber bushings as a function of frequency. Integration of the proposed method into multibody simulation software is also demonstrated with cosimulation between MSC.ADAMS and MATLAB software.
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    ArticlePublicationOpen Access
    Design sensitivity and optimization of powertrain mount system design parameters for rigid body modes and kinetic energy distributions
    (Springer Nature, 2020-08-24) Şendur, Polat; Tunç, B.; Mechanical Engineering; ŞENDUR, Polat
    This study evaluates the influences of the powertrain mount design parameters on the frequencies of powertrain rigid body modes and their kinetic energy distributions (KEDs), which play an important role in the low-frequency vibration of vehicles. A total of 12 design parameters (x, y, z position of mount locations and translational stiffness of the front and rear powertrain mounts) were evaluated in terms of their contributions to the aforementioned metrics. A multi-body dynamics simulation model was used in a 512-run modal analysis by varying the design variables across their common range, and the results were used in design sensitivity analysis. Response surface models for the frequencies of each powertrain rigid body mode and their KEDs were derived and subsequently used in optimization studies. It was shown that front and rear powertrain mount stiffness in y-direction has a strong influence on the frequency of powertrain lateral mode (21.5% and 24.5%, respectively). Front mount location in the x-direction demonstrates a strong influence on the pitch mode (25.7%), while the rear mount stiffness in the z-direction is the most influential on frequency of powertrain vertical mode with 29.1%. The location of the rear powertrain mount in the z-direction has a significant effect on the KED of fore-aft mode with 37.8% sensitivity. NSGA-II genetic algorithm with 100 generations was used for optimization to meet a set of design targets compiled from the literature. For the placement of the frequencies of powertrain rigid body modes with desired KED, design sensitivities, which are derived from a system-level approach, give important design direction to address the complex interactions between powertrain mount locations and stiffness and key metrics of the powertrain mount systems. Knowledge of design sensitivity of design parameters is important in the vehicle design cycle for OEMs to prioritize their design decisions. Finally, the optimization methodology is key to tune the design parameters to meet the conflicting design targets more efficiently.
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    An efficient design methodology for graded surface-based lattice structures using free-size optimization and enhanced mapping method
    (Elsevier, 2021-11-15) Şimşek, Uğur; Özdemir, Mirhan; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat
    In this paper, a novel Free-size Optimization based Graded Lattice Generation (FOGLG) method, that generates the functionally graded lattice (FGL) structures using free-size optimization, is proposed. In addition, the reconstruction method suitable for the construction of 3D FGL structures using Additive Manufacturing (AM) is presented. The proposed method employs the thickness information of each shell element obtained from a free-size optimization algorithm to determine the relative element densities, which collectively represent the set of design parameters. An additive manufacturing compatible mapping method of generating FGLs from 2D free-size optimization results is also proposed. The efficiency of the FOGLG was compared to the existing homogenization-based optimization (HMTO) and size optimization algorithms. The objective function of the three optimization strategies targets to minimize the total acceleration spectrum in the frequency range of interest. The effectiveness and validity of this new design method was also demonstrated from laser vibrometer measurements. The results show that the FOGLG reduces the overall acceleration spectrum by 3.6% and 19.4% compared to the HMTO and size optimization algorithms, respectively. High correlation between the numerical and experimental results validates the effectiveness of the proposed algorithm.
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    Enhancing the performance of Piezoelectric Energy Harvester under electrostatic actuation using a robust metaheuristic algorithm
    (Elsevier, 2023-02) Firouzi, Behnam; Abbasi, Ahmad; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat; Firouzi, Behnam; Abbasi, Ahmad
    This study proposes a novel shape optimization methodology based on evolutionary algorithms to maximize the harvesting energy from piezoelectric energy harvester stimulated by the β-emitted radioisotope. The parametric width function is used to model the piezoelectric layer non-prismatically. All the geometrical dimensions as well as parameters related to the parametric width function are optimized using the metaheuristic algorithms The piezoelectric layer partially covers the beam to obtain the optimal location of the piezoelectric layer. The pull-in instability causes the discharge in the system, and the piezoelectric layer converts the vibration of the released microcantilever into electricity. The nonlinear effects of electrostatic force and geometry are taken into account, and the differential equations governing the system are discretized utilizing the exact mode shapes of the system considering the geometrical effects of non-uniform microcantilever and the piezoelectric layer. The robust chaotic Harris Hawk optimization (RCHHO) algorithm is proposed for finding the optimal shape of the system. The performance of the proposed algorithm is compared with various metaheuristic algorithms in the literature. After optimizing the shape of the piezoelectric layer, the maximum voltage produced with the optimal model using the presented method was 8.105 times that of the classic model with rectangular piezoelectric layer used in previous works. Moreover, the maximum energy and average energy harvested in the optimal model were 61 and 7.22 times, respectively, of the non-optimal model.
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    On the application of Harris hawks optimization (HHO) algorithm to the design of microchannel heat sinks
    (Springer Nature, 2021-04) Abbasi, Ahmad; Firouzi, Behnam; Şendur, Polat; Mechanical Engineering; ŞENDUR, Polat; Abbasi, Ahmad; Firouzi, Behnam
    A novel Harris hawks optimization algorithm is applied to microchannel heat sinks for the minimization of entropy generation. In the formulation of the heat transfer model of the microchannel, the slip flow velocity and temperature jump boundary conditions have been taken into account. A variety of materials and fluids have also been evaluated to determine the optimal design of the microchannel. Since the main objective of this paper is to assess the search and exploration ability of the novel Harris Hawks algorithm, results are also benchmarked with those of commonly used particle swarm optimization, bees optimization algorithm, grasshopper optimization algorithm, whale optimization algorithm and dragonfly algorithm. Finally, results are compared to the analytical results and results obtained by the application of genetic algorithms. Results show that the Harris hawks algorithm has a superior performance in minimizing the entropy generation of the microchannel. The algorithm is also more computationally efficient compared to the aforementioned algorithms. Moreover, optimization results indicate that the use of copper for the microchannel and ammonia as the coolant leads to minimal entropy generation and, therefore, is considered as the best design. Considering the poor corrosive characteristics of copper, aluminum as the microchannel material is proposed as an alternative.