Browsing by Author "Yildirim, Afsin Talha"

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Investigation of compressive performance of 3D printed carbon fiber reinforced plastics
(Soc. for the Advancement of Material and Process Engineering, 2018) Eroglu, Fatih; Yildirim, Afsin Talha; Yesilyurt, Ogulcan; Sas, Hatice S.; Ciftci, Cihan; 0000-0001-9199-6437; AGÜ, Mühendislik Fakültesi, Makine Mühendisliği Bölümü; Eroglu, Fatih; Yildirim, Afsin Talha; Yesilyurt, Ogulcan; Ciftci, Cihan
The compressive performance of Carbon Fiber Reinforced Plastics (CFRP) is an extensive research area of crashworthy structures due to high Specific Energy Absorption (SEA) rates. However, the traditional composite manufacturing techniques are limiting the implementation of CFRP in crash components of automobile industry. These limitations can be minimized with 3D printing technology, which can be replaced with the traditional composite manufacturing techniques by providing flexibility especially in terms of geometric complexities. In this study, the compressive performance of 3D printed CFRP samples with square and circular cross-sections are examined with different thickness and fiber volume fraction values. SEA rates obtained from axial compressive tests are compared and compressive performance of 3D printed samples is optimized in terms of crashworthiness.
The Numerical Solutions for Stiff Ordinary Differential Equations by Using Interpolated Variational Iteration Method with Comparison to Exact Solutions
(AMER INST PHYSICS, 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA, 2018) Ciftci, Cihan; Cayci, Hatice Sinem Sas; Atay, Mehmet Tarik; Toker, Batuhan; Guncan, Berkay; Yildirim, Afsin Talha; AGÜ, Mühendislik Fakültesi, Makine Mühendisliği Bölümü
Recently proposed Interpolated Variational Iteration Method (IVIM) is used to find numerical solutions of stiff ordinary differential equations for both linear and nonlinear problems. The examples are given to illustrate the accuracy and effectiveness of IVIM method and IVIM results are compared with exact results. In recent analytical approximate methods based studies related to stiff ordinary differential equations, problems were solved by Adomian Decomposition Method and VIM and Homotopy Perturbation Method, Homotopy Analysis Method etc. In this study comparisons with exact solutions reveal that the Interpolated Variational Iteration Method (IVIM) is easy to implement. In fact, this method is promising methods for various systems of linear and nonlinear stiff ordinary differential equations as an initial value problem. Furthermore, IVIM is giving very satisfactory solutions when compared to exact solutions for nonlinear cases depending on the stiffness ratio of the stiff system to be solved.