Browsing by Author "Argeso, Hakan"
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Article Citation Count: 16ANALYTICAL SOLUTIONS TO VARIABLE THICKNESS AND VARIABLE MATERIAL PROPERTY ROTATING DISKS FOR A NEW THREE-PARAMETER VARIATION FUNCTION(Taylor & Francis inc, 2012) Argeşo, Ahmet Hakan; Manufacturing EngineeringAnalytical solutions of two different annular rotating disk problems are obtained under the assumptions of plane stress, isotropy, and small deformations. The first problem involves a homogeneous variable profile disk, whereas the second one is a functionally graded disk having a variation in elasticity modulus. For the variations of disk thickness and elasticity modulus in these problems, a new form of nonlinear function controlled by three parameters is introduced. The derivations of the closed form solutions for both type of rotating disk problems are carried out in a unified form. The closed form solutions are verified numerically by the nonlinear shooting method.Article Citation Count: 29Dynamic analysis of linear viscoelastic cylindrical and conical helicoidal rods using the mixed FEM(Academic Press Ltd- Elsevier Science Ltd, 2014) Argeşo, Ahmet Hakan; Argeso, Hakan; Calim, Faruk F.; Temel, Beytullah; Omurtag, Mehmet H.; Manufacturing EngineeringThe objective of this study is to investigate the influence of the rotary inertia on dynamic behavior of linear viscoelastic cylindrical and conical helixes by means of the Laplace transform-mixed finite element formulation and solution. The element matrix is based on the Timoshenko beam theory. The influence of rotary inertias is considered in the dynamic analysis, which is original in the literature. Rectangular, sine and step type of impulsive loads are applied on helices having rectangular cross-sections with various aspect ratios. The Kelvin and standard models are used for defining the linear viscoelastic material behavior; and by means of the correspondence principle (the elastic-viscoelastic analogy), the material parameters are replaced with their complex counterparts in the Laplace domain. The analysis is carried out in the Laplace domain and the results are transformed back to time space numerically by modified Durbin's algorithm. First, the solution algorithm is verified using the existing open sources in the literature and afterwards some benchmark examples such as conical viscoelastic rods are handled. (C) 2014 Elsevier Ltd. All rights reserved.Article Citation Count: 15Elastic analysis of variable profile and polar orthotropic FGM rotating disks for a variation function with three parameters(Springer Wien, 2017) Argeşo, Ahmet Hakan; Argeso, Hakan; Manufacturing EngineeringAnalytical solutions are developed for the analysis of elastic polar orthotropic functionally graded annular disks rotating with constant angular velocity. The formulations are carried out by presuming a state of plane stress and small deformations. The elasticity moduli and thickness are varied radially by a nonlinear function controlled by three parameters, while the radial variation of density may be defined by any form of continuous function. Poisson's ratios are taken to be constant. Annular disks having traction-free inner and outer surfaces, and annular disks mounted on a circular rigid shaft having traction-free outer surface are studied separately. The analytical solutions are verified numerically by the use of a computational model based on the nonlinear shooting method. An analysis that inspects the effects of the degree of orthotropy is presented. Elastic limit angular velocities are determined according to Hosford's yield criteria. Stress, displacement and strain profiles are compared within the elastic range.Article Citation Count: 0Elastostatics of star-polygon tile-based architectured planar lattices(Elsevier Sci Ltd, 2023) Argeşo, Ahmet Hakan; Gleadall, Andrew; Soyarslan, Celal; Argeso, Hakan; Sozumert, Emrah; Manufacturing Engineering; Department of Mechatronics EngineeringA panoptic view of architectured planar lattices based on star-polygon tilings was developed. Four starpolygon-based lattice sub-families, formed of systematically arranged triangles, squares, or hexagons, were investigated numerically and experimentally. Finite-element-based homogenization allowed computation of Poisson's ratio, elastic modulus, shear modulus, and planar bulk modulus. A comprehensive understanding of the range of properties and micromechanical deformation mechanisms was developed. Adjusting the star-polygon angle achieved an over 250-fold range in elastic modulus, over a 10-fold range in density, and a range of -0.919 to +0.988 for Poisson's ratio. Additively manufactured lattices, achieved by novel printing strategies, showed good agreement in properties. Parametric additive manufacturing procedures for all lattices are available on www.fullcontrol.xyz/#/models/1d3528. Three of the four sub-families exhibited in-plane elastic isotropy. One showed high stiffness with auxeticity at low density and a primarily axial deformation mode as opposed to bending deformation for the other three lattices. The range of achievable properties, demonstrated with property maps, proves the extension of the conventional material-property space. Lattice metamaterials with Triangle-Triangle, Kagome, Hexagonal, Square, Truncated Archimedean, Triangular, and Truncated Hexagonal topologies have been studied in the literature individually. Here, it is shown that these structures belong to the presented overarching lattice family. (c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Article Citation Count: 4A frequency domain boundary element formulation for dynamic interaction problems in poroviscoelastic media(Springer, 2014) Argeşo, Ahmet Hakan; Mengi, Yalcin; Manufacturing EngineeringA unified formulation is presented, based on the boundary element method, to perform the interaction analysis for the problems involving poroviscoelastic media. The proposed formulation permits the evaluation of all the elements of impedance and input motion matrices at a single step in terms of system matrices of boundary element method without solving any special problem, such as, unit displacement or load problem, as required by conventional methods. It further eliminates the complicated procedure and the need for using scattering analysis in the evaluation of input motion functions. The formulation is explained by considering a simple interaction problem involving an inclusion embedded in an infinite poroviscoelastic medium, which is under the influence of a dynamic excitation induced by seismic waves. In the formulation, an impedance relation is established for this interaction problem, suitable for performing the interaction analysis by substructure method, which permits carrying out the analysis for inclusion and its surrounding medium separately. The inclusion is first treated as poroviscoelastic, then viscoelastic and finally rigid, where the formulation in each of these cases is obtained consecutively as a special case of the previous one. It is remarkable to note that, a cavity problem where there is a hole in place of inclusion can be also considered within the framework of the present formulation. The formulation is assessed by applying it to some sample problems. The extension of the formulation to other types of interaction problems, such as, multi-inclusion problems, the analyses of foundations supported by a poroviscoelastic medium, etc., will be the subject of a separate study.Article Citation Count: 13Skeletonization-based beam finite element models for stochastic bicontinuous materials: Application to simulations of nanoporous gold(Cambridge Univ Press, 2018) Argeşo, Ahmet Hakan; Argeso, Hakan; Soyarslan, Celal; Manufacturing Engineering; Department of Mechatronics EngineeringAn efficient representative volume element generation strategy is developed in modeling nanoporous materials. It uses periodic 3D beam finite element (FE) models derived from skeletonization of spinodal-like stochastic microstructures produced by a leveled random field. To mimic stiffening with agglomeration of the mass at junctions, an increased Young's modulus is assigned to the elements within the junction zone. The effective Young's modulus, Poisson's ratio, and universal anisotropy index are computed. A good agreement of the Young's modulus predictions with those obtained from experimental results for phase volume fractions 0.20 < phi(B) < 0.50 is observed. Moreover, the elastic anisotropy index of the generated beam networks shows sufficient proximity to isotropy. Finally, it is demonstrated that, as compared to the simulation statistics of voxel-FE models, for the beam-FE models over 500-fold computational acceleration with 250-fold less memory requirement is provided.