Browsing by Author "Sözen, Betül"

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Application of the Bees Algortihm Upon Hydraulic Cylinder Design and Optimization
(2022) Sözen, Betül; Kalyoncu, Mete; Şahin, Ömer Sinan
In this study, mass minimization of a simple double-acting hydraulic cylinder has been studied using The Bees Algorithm (BA) for a specific force and known material, considering the buckling and pressure constraints. A Hydraulic cylinder is a hydraulic actuator that creates linear movement by converting hydraulic energy back to a mechanical movement. Hydraulic-driven working machines are widespread in the industry today. Hydraulic cylinders are used in mobile applications such as container lifting devices, excavators, dump trucks, loaders, graders and dozers. Weight reduction in these cylinders plays a fundamental role in the performance of the machine in terms of lifting capacity, speed, costing, etc. The Bees Algorithm is a metaheuristic algorithm that mimics the natural foraging behavior of honey bees to find the optimum solutions. The advantages over other algorithms are its ability to search both locally and globally and being applicable for several optimization problems with the chance to be integrated with other algorithms. In this study, it is also aimed to determine the optimal parameters of the bees algorithm for minimum computation cost.
Citation - WoS: 4
Citation - Scopus: 4
Dynamic Characterization and Damage Analysis for the Thermoplastic Fiber-Reinforced Epoxy Composites Exposed To Repeated Low Velocity Impact
(Sage Publications Ltd, 2023) Sözen, Betül; Coşkun, Taner; Sahin, Ömer Sinan
In the current study, contrary to conventional fiber-reinforced composites, polyamide fiber was used as reinforcement material, and the effects of thermoplastic fiber reinforcement on repeated low velocity impact (LVI) responses of composites were examined. In this regard, polyamide fiber-reinforced composites were fabricated using the vacuum-assisted hand lay-up method (VAHLM) and then exposed to repeated LVI loadings. Experimental tests were performed on the specimens for 100 impacts with a constant velocity of 3 m/s, which is equivalent to 25.2 J, and the impacts of repeated LVI loadings on the dynamic responses such as peak force, energy absorbing/rebounding, total impulse, bending stiffness and contact stiffness were examined. Moreover, the damage mechanisms resulting from the relative damage accumulation depending on the impact numbers were examined. According to the findings, the thermoplastic polyamide fibers absorbed more than 60% of the applied energy, and the absorbed energy increased with ascending impact number. Furthermore, the thermoplastic fiber-reinforced epoxy composites gained stiffness with increasing impact, which was linked to the thermoplastic chain structure. Despite quite a number of impact loadings, no serious damage mechanisms such as fiber breakage, perforation, or penetration were observed, and the specimens maintained their structural integrity. Due to the higher energy absorption of thermoplastics, the utilization of polyamide fibers in composites has been found to be well suited for applications subjected to repeated impacts.
Dynamic Responses and Damage/Element Composition Analysis of Thermoplastic Polyamide Reinforced Epoxy Composites Exposed To Hci Environment
(Wiley, 2024) Coşkun, Taner; Sözen, Betül; Şahin, Ömer Sinan
The present study aimed to examine how the corrosive environment affected the low-velocity impact (LVI) characteristics and damage mechanisms of thermoplastic polyamide fiber-reinforced polymer (PFRP) composites. In this regard, composite specimens were subjected to corrosive environment containing 10 wt.% diluted HCl for one week and one month before LVI tests. To investigate the hostile effects of the corrosive environment on the composites, scanning electron microscope (SEM) coupled with energy-dispersive X-ray system (EDX) analyses were carried out, and thus variations in the elemental composition and damage mechanisms for the composites were determined. According to the examinations, it was discovered that the degradation in LVI responses, such as contact stiffness, bending stiffness, and peak force, increased with longer aging time, as expected. Furthermore, when the aging effect was assessed based on absorbed energy, the specimens exposed to a corrosive environment for one month exhibited the highest energy absorption compared to the control and 1-week-immersed ones. The degrading effect of the HCI environment appeared as higher damage severity on the composites, which was also detected from the SEM images. According to the SEM analyses, matrix cracks, corrosion pits, and local surface imperfections caused by ion exchange are detected in 1-week-immersed specimens, while more serious damage mechanisms such as fiber breakage and fiber pull-out are noted in specimens exposed to corrosive environment for 1 month. Furthermore, approximately 6.33 wt.% CI was identified in the composites after 1 month of aging, which was associated with the hydrolysis triggered by rise in the composite's damage severity.
Citation - WoS: 4
Citation - Scopus: 3
The Optimal Design of Honeycomb Sandwich Panel Based on the Coupled-Effects of Geometric Parameters
(Taylor & Francis Inc, 2023) Sözen, Betül; Coskun, Taner; Yozgatli, Ibrahim; Sahin, Omer Sinan
In this study, numerical models were developed with three different core widths and heights, and numerical analyses were performed to investigate the coupled effects of design parameters on stress and structural weight under gravitational prestress. In addition, the design parameters were optimized using the Response Surface Methodology (RSM), and thus core width and height were determined, providing minimum weight and maximum strength. The numerical findings were validated by comparing them to the statistical-based optimization results. On the other hand, thermal pre-stressed structural analyses were performed to assess the effect of the elasticity modulus and thermal expansion coefficients of the adhesives on the structural responses. The current study demonstrated that core width was more effective than core height on stress and deformation responses, and also that ascending core width had an adverse impact on bending stiffness. Furthermore, the optimum core width and height were determined as 5.0042 and 14.844 mm, respectively, using RSM. The maximum stress and weight responses of the sandwich structure with optimal design parameters were also found as 83.455 kPa and 2.2667 g. It was revealed that impacts of core height become more noticeable with larger core widths, and they should not be considered separately.