Browsing by Author "Bozyigit,B."

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Citation Count: 11
Differential transform method and Adomian decomposition method for free vibration analysis of fluid conveying Timoshenko pipeline
(Techno-Press, 2017) Bozyigit,B.; Yesilce,Y.; Catal,S.
The free vibration analysis of fluid conveying Timoshenko pipeline with different boundary conditions using Differential Transform Method (DTM) and Adomian Decomposition Method (ADM) has not been investigated by any of the studies in open literature so far. Natural frequencies, modes and critical fluid velocity of the pipelines on different supports are analyzed based on Timoshenko model by using DTM and ADM in this study. At first, the governing differential equations of motion of fluid conveying Timoshenko pipeline in free vibration are derived. Parameter for the nondimensionalized multiplication factor for the fluid velocity is incorporated into the equations of motion in order to investigate its effects on the natural frequencies. For solution, the terms are found directly from the analytical solution of the differential equation that describes the deformations of the cross-section according to Timoshenko beam theory. After the analytical solution, the efficient and easy mathematical techniques called DTM and ADM are used to solve the governing differential equations of the motion, respectively. The calculated natural frequencies of fluid conveying Timoshenko pipelines with various combinations of boundary conditions using DTM and ADM are tabulated in several tables and figures and are compared with the results of Analytical Method (ANM) where a very good agreement is observed. Finally, the critical fluid velocities are calculated for different boundary conditions and the first five mode shapes are presented in graphs. © 2017 Techno-Press, Ltd.
Citation Count: 0
Dynamic response of single and multi-span beams under a moving load using dynamic stiffness formulations and Galerkin's method
(European Association for Structural Dynamics, 2020) Bozyigit,B.; Acikgoz,S.; Yesilce,Y.
This paper is concerned with the dynamic response analysis of single and multi-span beams under moving point loads. The Dynamic Stiffness Method (DSM) is used to calculate the mode frequencies and shapes of single, two and four-span Bernoulli-Euler beams. The exact mode shapes obtained from dynamic stiffness formulations are used to derive generalized mass, stiffness and force terms for normal modes using Galerkin 's method. This enables efficient and accurate calculation of the time-history response of the investigated structures. This is demonstrated by comparing the results from this study with advanced finite element simulations of the same problem from the literature. The results validate the accuracy of this approach and demonstrate how this technique can be used to model dynamic amplification of bridges under the influence of moving loads. © 2020 European Association for Structural Dynamics. All rights reserved.
Citation Count: 1
Dynamic stiffness formulations for harmonic response of infilled frames
(Techno-Press, 2018) Bozyigit,B.; Yesilcea,Y.
In this paper, harmonic responses of infilled multi-storey frames are obtained by using a single variable shear deformation theory (SVSDT) and dynamic stiffness formulations. Two different planar frame models are used which are fully infilled and soft storey. The infill walls are modeled by using equivalent diagonal strut approach. Firstly, free vibration analyses of bare frame and infilled frames are performed. The calculated natural frequencies are tabulated with finite element solution results. Then, harmonic response curves (HRCs) of frame models are plotted for different infill wall thickness values. All of the results are presented comparatively with Timoshenko beam theory results to reveal the effectiveness of SVSDT which considers the parabolic shear stress distribution along the frame member cross-sections. Copyright © 2018 Techno-Press, Ltd.
Citation Count: 3
Free vibration analysis of arch-frames using the dynamic stiffness approach
(EXTRICA, 2020) Bozyigit,B.; Yesilce,Y.; Acikgoz,S.
The aim of this study is to investigate free vibration characteristics of arch-frames which consist of two columns and an arch. Firstly, an exact formulation of the problem is presented using the Dynamic Stiffness Method (DSM). The end forces and displacements of column elements are obtained analytically using Timoshenko beam theory (TBT). These are then combined with the end forces and displacements of the semi-circular arch, which is modeled with exact curved beam elements that consider axial and shear deformations and rotational inertia. By employing standard assembly and bisection based root finding procedures, exact free vibration analysis of the whole vibrating system is carried out. Then, in an effort to simplify the formulations, an approach based on approximating the arch as assembly of linear straight beam segments is presented. The calculated natural frequencies using DSM for both exact and approximate results are then tabulated for comparison purposes. The mode shapes are also compared. The results show that the proposed model simplification is effective and produces accurate mode frequency and shape estimations. © 2020 Baran Bozyigit, et al.
Citation Count: 17
Free vibration and harmonic response of cracked frames using a single variable shear deformation theory
(Techno-Press, 2020) Bozyigit,B.; Yesilce,Y.; Wahab,M.A.
The aim of this study is to calculate natural frequencies and harmonic responses of cracked frames with general boundary conditions by using transfer matrix method (TMM). The TMM is a straightforward technique to obtain harmonic responses and natural frequencies of frame structures as the method is based on constructing a relationship between state vectors of two ends of structure by a chain multiplication procedure. A single variable shear deformation theory (SVSDT) is applied, as well as, Timoshenko beam theory (TBT) and Euler-Bernoulli beam theory (EBT) for comparison purposes. Firstly, free vibration analysis of intact and cracked frames are performed for different crack ratios using TMM. The crack is modelled by means of a linear rotational spring that divides frame members into segments. The results are verified by experimental data and finite element method (FEM) solutions. The harmonic response curves that represent resonant and anti-resonant frequencies directly are plotted for various crack lengths. It is seen that the TMM can be used effectively for harmonic response analysis of cracked frames as well as natural frequencies calculation. The results imply that the SVSDT is an efficient alternative for investigation of cracked frame vibrations especially with thick frame members. Moreover, EBT results can easily be obtained by ignoring shear deformation related terms from governing equation of motion of SVSDT. Copyright © 2020 Techno-Press, Ltd.
Citation Count: 12
Free vibrations of axial-loaded beams resting on viscoelastic foundation using Adomian decomposition method and differential transformation
(Elsevier B.V., 2018) Bozyigit,B.; Yesilce,Y.; Catal,S.
The aim of this paper is to reveal the effectiveness of Adomian decomposition method (ADM) and differential transform method (DTM) on free vibrations of axial-loaded Timoshenko beams resting on viscoelastic foundation. The effects of axial compressive load, modulus of subgrade reaction and foundation damping on natural frequencies of beam model are studied using various boundary conditions. The results of DTM and ADM are tabulated with exact results that obtained from analytical formulations where an excellent agreement is observed. Moreover, the dynamic stiffness method (DSM) which uses the exact mode shapes is applied to verify the analytical results. The accuracy of mathematical tools DTM and ADM is demonstrated by several numerical examples. The first four mode shapes are depicted. It is highlighted that application of DTM, ADM and DSM can be extended without any difficulties for free vibrations of beam assembly structures that resting on viscoelastic foundation. © 2018 Karabuk University
Citation Count: 4
Investigation of natural frequencies of multi-bay and multi-storey frames using a single variable shear deformation theory
(Techno-Press, 2018) Bozyigit,B.; Yesilce,Y.
This study concerns about calculating exact natural frequencies of frames using a single variable shear deformation theory (SVSDT) which considers the parabolic shear stress distribution across the cross section. Free vibration analyses are performed for multi-bay, multi-storey and multi-bay multi-storey type frame structures. Dynamic stiffness formulations are derived and used to obtain first five natural frequencies of frames. Different beam and column cross sections are considered to reveal their effects on free vibration analysis. The calculated natural frequencies are tabulated with the results obtained using Euler-Bernoulli Beam Theory (EBT) and Timoshenko Beam Theory (TBT). Moreover, the effects of inner and outer columns on natural frequencies are compared for multi-bay frames. Several mode shapes are plotted. Copyright © 2018 Techno-Press, Ltd.
Citation Count: 18
Transfer matrix formulations and single variable shear deformation theory for crack detection in beam-like structures
(Techno-Press, 2020) Bozyigit,B.; Yesilce,Y.; Wahab,M.A.
This study aims to estimate crack location and crack length in damaged beam structures using transfer matrix formulations, which are based on analytical solutions of governing equations of motion. A single variable shear deformation theory (SVSDT) that considers parabolic shear stress distribution along beam cross-section is used, as well as, Timoshenko beam theory (TBT). The cracks are modelled using massless rotational springs that divide beams into segments. In the forward problem, natural frequencies of intact and cracked beam models are calculated for different crack length and location combinations. In the inverse approach, which is the main concern of this paper, the natural frequency values obtained from experimental studies, finite element simulations and analytical solutions are used for crack identification via plots of rotational spring flexibilities against crack location. The estimated crack length and crack location values are tabulated with actual data. Three different beam models that have free-free, fixed-free and simple-simple boundary conditions are considered in the numerical analyses. Copyright © 2020 Techno-Press, Ltd.