Browsing by Author "Pekol, Sena"

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1956 yılında Ankara Ayaş'ta kurulan ve uzun yıllar varlığını sürdüren tamirhane
(Bilkent University, 2018) Yıldız, Önder; Yeldan, Alper; Pekol, Sena; Çetin, Ceren
Bu araştırmada Cumhuriyet dönemi sonrasındaki sanayi gelişiminin Ankara’daki etkileri ve bir yansıması olarak gelişen sanayi bölgelerinden uzakta, Ankara’nın Ayaş ilçesinde kurulan bir tamirhane incelenmiştir. özellikle otomotiv sanayinin Cumhuriyet döneminden günümüze ilerleyişi, sektörün getirdiği ikincil ihtiyaçlar, bu ihtiyaçların eğitim üzerine yansıması araştırılmıştır. Ayaş’ta kurulan tamirhane, dönemin sanayi yapısı çerçevesinde değerlendirilmiş; orada kurulmasının sebebi kurucularının aile yapısı, eğitimleri ve Ayaş’ın sosyo-kültürel yapısıyla birlikte değerlendirilmiştir.
Open Access
A computational design framework for lubrication interfaces with active micro-textures
(The American Society of Mechanical Engineers, 2024-08-27) Pekol, Sena; Kılınç, Özge; Temizer, İlker
The major goal of the present study is to develop a computational design framework for the active control of hydrodynamically lubricated interfaces. The framework ultimately delivers an electrode distribution on an elastomeric substrate such that a voltage-controlled texture may be induced on its surface. This enables the setup to attain a desired time-dependent macroscopic lubrication response. The computational framework is based on a numerically efficient two-stage design approach. In the first stage, a topology optimization framework is introduced for determining a microscopic texture and the uniform modulation of its amplitude. The objective is to attain the targeted fluid flux or frictional traction signals based on the homogenization-based macroscopic response of the texture. As a minor goal, a novel unit cell geometry optimization feature will be developed which will enable working in a design space that is as unrestricted as possible. The obtained designs are then transferred to the second stage where the electrode distribution on a soft substrate is determined along with the voltage variation that delivers the desired amplitude variation. The first stage operates in a two-dimensional setting based on the Reynolds equation whereas the second stage operates in a three-dimensional setting based on an electroelasticity formulation. The two stages are heuristically coupled by transferring the texture topology to the electrode distribution through a projection step. The viability of such an active lubrication interface design approach is demonstrated through numerous examples that methodically investigate the central features of the overall computational framework.
Open Access
Active lubrication interfaces with tunable micro-textures
(2023-07) Pekol, Sena
This thesis investigates a homogenization-based space-time optimization framework in the context of hydrodynamic lubrication in order to design micro-textures which can be actively controlled through external stimuli. The response at the interface is established via the Reynolds equation to describe the physics of the lubrication for a small film thickness. Subsequently, the interface is subjected to multiscale analysis and effective macroscopic parameters are derived via homogenization method. In order to calculate the macroscopic parameters, Finite Element (FE) formulation is employed and the implementation of the parameters in the in-house FE code is demonstrated. For the suboptimality problem due to typically employed fixed unit cell in FE analysis, a geometry optimization scheme is developed. Thereafter, a sensitivity based topology optimization framework is introduced with the aim of identifying the spatial distribution and temporal variation of the micro-texture, and the shape of the unit cell which together help achieve the targeted lubrication response. The performance of the employed framework is assessed through objectives which ultimately determine the macroscopic flux at the interface as well as the frictional traction that is associated with the macroscopic dissipation at the interface. Finally, three-dimensional realizations are constructed for active micro-textures by adopting a readily deployable experimental architecture.