Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 7Citation - Scopus: 7A Comprehensive Study on Burst Pressure Performance of Aluminum Liner for Hydrogen Storage Vessels(ASME, 2021) Kangal, Serkan; Sayı, Abdülmecit Harun; Ayakdaş, Ozan; Kartav, Osman; Aydın, Levent; Artem, Hatice Seçil; Aktaş, Engin; Yücetürk, Kutay; Tanoğlu, Metin; Kandemir, Sinan; Beylergil, BertanThis paper presents a comparative study on the burst pressure performance of aluminum (Al) liner for type-III composite overwrapped pressure vessels (COPVs). In the analysis, the vessels were loaded with increasing internal pressure up to the burst pressure level. In the analytical part of the study, the burst pressure of the cylindrical part was predicted based on the modified von Mises, Tresca, and average shear stress criterion (ASSC). In the numerical analysis, a finite element (FE) model was established in order to predict the behavior of the vessel as a function of increasing internal pressure and determine the final burst. The Al pressure vessels made of Al-6061-T6 alloy with a capacity of 5 L were designed. The manufacturing of the metallic vessels was purchased from a metal forming company. The experimental study was conducted by pressurizing the Al vessels until the burst failure occurred. The radial and axial strain behaviors were monitored at various locations on the vessels during loading. The results obtained through analytical, numerical, and experimental work were compared. The average experimental burst pressure of the vessels was found to be 279 bar. The experimental strain data were compared with the results of the FE analysis. The results indicated that the FE analysis and ASSC-based elastoplastic analytical approaches yielded the best predictions which are within 2.2% of the experimental burst failure values. It was also found that the elastic analysis underestimated the burst failure results; however, it was effective for determining the critical regions over the vessel structure. The strain behavior of the vessels obtained through experimental investigations was well correlated with those predicted through FE analysis.Article Citation - WoS: 3Citation - Scopus: 3Magnetically Driven Foldable Shell Type Swimmers at Stokes Flow(Springer, 2019) Özdemir, İzzetThis paper focuses on the interaction of low Reynolds number (Re) flows and thin shell type deformable structures in the context of flexible body locomotion and addresses the coupled field problem through a numerical solution framework. The thin structure is discretized by enhanced three-node finite elements and coupled with boundary element based treatment of Stokes flow in a monolithic manner. The locomotion is triggered and driven by an external magnetic field that generates displacement dependent body couples over the magnetically sensitive parts of the flexible structure. A particular novelty of the paper is the use of internal hinges through which very large rotations and structural deformations can be combined in an efficient way. Using this concept; new, on the fly locomotion direction reversal mechanisms can be generated as demonstrated by the foldable bi-directional swimmer.Article Citation - WoS: 1Citation - Scopus: 1Resistive Force Theory-Based Analysis of Magnetically Driven Slender Flexible Micro-Swimmers(Springer Verlag, 2017) Özdemir, İzzetResistive force theory is concise and reliable approach to resolve flow-induced viscous forces on submerged bodies at low Reynolds number flows. In this paper, the theory is adapted for very thin shell-type structures, and a solution procedure within a nonlinear finite element framework is presented. Flow velocity proportional drag forces are treated as configuration-dependent external forces and embedded in a commercial finite element solver (ABAQUS) through user element subroutine. Furthermore, incorporation of magnetic forces induced by external fields on magnetic subdomains of such thin-walled structures is addressed using a similar perspective without resolving the magnetic field explicitly. The treatment of viscous drag forces and the magnetic body couples is done within the same user element formalism. The formulation and the implementation are verified and demonstrated by representative examples including the bidirectional swimming of thin strips with magnetic ends.Article Citation - WoS: 9Citation - Scopus: 12Structural Analyses and Assessment of Historical Kamanlı Mosque in Izmir, Turkey(American Society of Civil Engineers (ASCE), 2010) Teomete, Egemen; Aktaş, EnginHistorical structures are one of the most precious pieces of cultural accumulation. In this study, an interdisciplinary work was conducted to assess the structural condition of a historical masonry structure, Urla Kamanl Mosque in zmir, Turkey. The structure is a member of group of structures, Yahi Bey Complex, which includes a Turkish bath, a tomb, two fountains, and a primary school. The structure dates back to early 14th century to mid-15th century. History investigation, measurement survey, long-term settlement, and moisture observations were conducted. Nondestructive and destructive material tests were performed on stone, brick, and mortar. 3D finite-element model of the structure was used to investigate the critical locations of the structure under its self-weight, seismic load, and settlement load. Linear elastic and nonlinear settlement analyses were conducted to investigate the reason for massive cracks challenging the structural integrity. © 2010 ASCE.Article Citation - WoS: 78Citation - Scopus: 88Nonlinear Finite Element Modeling of Reinforced Concrete Structures Under Impact Loads(American Concrete Institute, 2009) Saatçi, Selçuk; Vecchio, Frank J.The methods available in the literature for the analysis of reinforced concrete (RC) structures subjected to impact loads generally exhibit some deficiencies in aspects relating to applicability, practicality, and accuracy. The shear-dominant behavior of RC members under impact loads creates another significant shortcoming, because modeling the shear behavior of RC has long been a challenging issue. This study aims to present and verify a nonlinear finite element analysis procedure employing the Disturbed Stress Field Model, based on a smeared rotating crack approach, as an advanced method of modeling shear behavior under impact conditions. The proposed methodology has a wide range of applicability, and displays fast solution time while providing extensive and accurate information on structural behavior. The methodology was tested by analyzing a set of RC beams subjected to impact loads. A high level of accuracy was demonstrated in various comparisons between test and analysis results, including peak and residual displacements, crack profiles, and reinforcement strains.