Person: UZUN, BÜŞRA
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UZUN
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BÜŞRA
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Publication Buckling analysis of nanobeams with deformable boundaries via doublet mechanics(Springer, 2021-09-07) Civalek, Ömer; Uzun, Büşra; Yaylı, Mustafa Özgür; UZUN, BÜŞRA; YAYLI, MUSTAFA ÖZGÜR; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0002-7636-7170; 0000-0003-2231-170X; AAJ-6390-2021; ABE-6914-2020Buckling analysis of nanobeams with deformable boundary conditions is researched within the framework of doublet mechanics. This theory is an alternative nanomechanics theory for continuum modeling of the granular micromaterials. Doublet mechanics theory takes into consideration the small size parameter due to dealing with also granular nanosized structures. In many studies, rigid supporting conditions are explored in the nanomechanical analysis of beams. Even though the supporting conditions are accepted as undeformable, it is not possible to provide the desired rigidity in practice. A few studies have been conducted to explore the effects of deformable boundaries. In the present work, Fourier sine series as well as Stokes' transformation are utilized to attain the eigenvalue formulation and eigenvector characteristics of the problem. The combination of these two methods is a new approach in applied mechanics; at the same time, it is planned to create a bridge between rigid and deformable boundary conditions. By solving various examples, the accuracy of the proposed method has been tested and an excellent agreement has been achieved with the literature. In addition, the effect of the springs in the boundaries on the critical buckling load has been examined and given in a series of graphs.Publication Finite element formulation for nano-scaled beam elements(Wiley, 2021-12-02) Civalek, Ömer; Uzun, Buşra; Yaylı, Mustafa Özgür; YAYLI, MUSTAFA ÖZGÜR; UZUN, BÜŞRA; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0003-1907-9479; 0000-0003-2231-170X; ABE-6914-2020; AAJ-6390-2021In the present study, size-dependent buckling and free vibration behaviors of single-walled boron nitride nanotube (SWBNNT) are performed in conjunction with various size-dependent elasticity theories. Modified couple stress theory (MCST) and Eringen's nonlocal elasticity theory are used for size-dependent models of SWBNNT. Also, the buckling loads and frequencies are obtained by using local theory to emphasize the effects and differences of these size-dependent theories. Consequently, three different elasticity theories (two non-classical and one classical) are utilized to achieve the detailed buckling and vibration analyses of SWBNNT. In this study, the buckling loads and frequencies of SWBNNTs are obtained via presented finite element formulation. In the finite element procedures based on two different size-dependent elasticity theories, matrices containing the small size parameter are derived. With these matrices containing the small size parameters, eigenvalue problems for buckling and free vibration analyses are formed. The buckling loads and frequency values of the SWBNNTs under the size effect are obtained. The influences of the dimensionless nonlocal parameter, dimensionless material length scale parameter, length-to-diameter ratio and boundary conditions on nanotube's buckling and vibration characteristics are investigated. In addition to these influences, the rotary inertia effect neglected in many other studies is also examined.Publication Winkler-pasternak foundation effect on the buckling loads of arbitrarily rigid or restrained supported nonlocal beams made of different fgm and porosity distributions(Wiley-v C H Verlag Gmbh, 2023-10-20) Uzun, Büşra; UZUN, BÜŞRA; Yaylı, Mustafa Özgür; YAYLI, MUSTAFA ÖZGÜR; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Kardiyoloji Anabilim Dalı.; 0000-0002-7636-7170; 0000-0003-2231-170X; ABE-6914-2020; AAJ-6390-2021The present research investigates lateral stability of a functionally graded nanobeam using Eringen's differential nonlocal elasticity model under rigid (clamped, pinned, free) and deformable (lateral, rotational restraints) boundary conditions. Sigmoid and power law have been employed as grading laws to study the influence of the material distribution on the snap-buckling analysis of a nanobeam with arbitrary boundary conditions. Moreover, Fourier sine series with Stokes' transformation are employed to investigate the effects of boundary conditions on the stability response of nanobeams embedded in a Pasternak foundation. A parametric study has been performed to investigate the effect of deformable boundaries, Pasternak foundation and small-scale parameters on the stability response of the nanobeam and the results have been presented in a series of tables and figures. It has been observed that consideration of the small-scale parameter, Pasternak foundation, deformable boundaries and functionally grading index (of sigmoid and power-law) are essential while analyzing the static stability response. The obtained analytical results may be used as benchmarks in future researches of functionally graded nanobeams embedded in an elastic medium.Publication Free vibration analysis of BNNT with different cross-sections via nonlocal FEM(Univ Tehran, Danishgah-i Tihran, 2018-12-01) Numanoğlu, Hayri Metin; Civalek, Omer; Uzun, Büşra; UZUN, BÜŞRA; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-7636-7170; ABE-6914-2020In the present study, free vibration behaviors of carbon nanotube (CNT) and boron nitride nanotube (BNNT) have been investigated via Eringen's nonlocal continuum theory. Size effect has been considered via nonlocal continuum theory. Nanotubes have become popular in the world of science thanks to their characteristic properties. In this study, free vibrations of Boron Nitride Nanotube (BNNT) and Carbon Nanotube (CNT) are calculated using the Nonlocal Elasticity Theory. Frequency values are found via both analytical and finite element method (FEM). Galerkin weighted residual method is used to obtain the finite element equations. BNNT and CNT are modeled as Euler - Bernoulli Beam and solutions are gained by using four different cross-section geometries with three boundary conditions. Selected geometries are circle, rectangle, triangle, and square. Frequency values are given in tables and graphs. The effect of cross-section, boundary conditions and length scale parameter on frequencies has been investigated in detail for BNNT.Publication Axial and torsional free vibrations of restrained single-walled boron nitride nanotube (swbnnt) embedded in an elastic medium via nonlocal strain gradient theory(Taylor & Francis Ltd, 2022-11-22) Civalek, Ömer; Uzun, Büşra; UZUN, BÜŞRA; Yaylı, Mustafa Özgür; YAYLI, MUSTAFA ÖZGÜR; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-7636-7170; 0000-0003-1907-9479; 0000-0003-2231-170X; ABE-6914-2020; AAJ-6390-2021The effect of the surrounding elastic matrix on the axial and torsional vibrations of embedded single-walled boron nitride nanotube (SWBNNT) is studied in this work. The SWBNNT is modeled as a nanorod and the nonlocal strain gradient theory is utilized to derive the size-dependent equation of motion. Also, the surrounding elastic matrix is simulated by employing a one-parameter foundation model. Stokes' transformation method as an accurate and efficient mathematical tool in conjunction with the Fourier trigonometric series solution is utilized to discretize the equation of motion. These two mathematical methods create two different eigenvalue problems, which can solve any boundary conditions for torsional and axial vibrations. Calculated Eigen frequencies are validated with earlier works in the literature. The effects of the surrounded elastic matrix parameter together with the other deformable boundary coefficients and also the small scale parameter on the axial and torsional vibration frequencies are researched and some conclusions are outlined.