Aktaş, Engin
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AktaÅ, E.
Aktas, Engin
Aktaş, E.
Aktaş, E
Aktas, E.
Aktas, E
Aktai, Engin
Aktas, Engin
Aktaş, E.
Aktaş, E
Aktas, E.
Aktas, E
Aktai, Engin
Job Title
Email Address
enginaktas@iyte.edu.tr
Main Affiliation
03.03. Department of Civil Engineering
Status
Current Staff
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Sustainable Development Goals
1NO POVERTY
1
Research Products
2ZERO HUNGER
0
Research Products
3GOOD HEALTH AND WELL-BEING
0
Research Products
4QUALITY EDUCATION
3
Research Products
5GENDER EQUALITY
0
Research Products
6CLEAN WATER AND SANITATION
1
Research Products
7AFFORDABLE AND CLEAN ENERGY
4
Research Products
8DECENT WORK AND ECONOMIC GROWTH
2
Research Products
9INDUSTRY, INNOVATION AND INFRASTRUCTURE
16
Research Products
10REDUCED INEQUALITIES
0
Research Products
11SUSTAINABLE CITIES AND COMMUNITIES
10
Research Products
12RESPONSIBLE CONSUMPTION AND PRODUCTION
4
Research Products
13CLIMATE ACTION
1
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14LIFE BELOW WATER
2
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15LIFE ON LAND
1
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
0
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17PARTNERSHIPS FOR THE GOALS
0
Research Products
Documents
50
Citations
715
h-index
14
Documents
43
Citations
615
Scholarly Output
65
Articles
37
Views / Downloads
177090/28850
Supervised MSc Theses
15
Supervised PhD Theses
3
WoS Citation Count
542
Scopus Citation Count
621
Patents
0
Projects
3
WoS Citations per Publication
8.34
Scopus Citations per Publication
9.55
Open Access Source
40
Supervised Theses
18
| Journal | Count |
|---|---|
| Journal of Composite Materials | 5 |
| Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi | 2 |
| Journal of Architectural Engineering | 2 |
| International Journal of Adhesion and Adhesives | 2 |
| Journal of Intelligent Material Systems and Structures | 2 |
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65 results
Scholarly Output Search Results
Now showing 1 - 10 of 65
Conference Object Improvement of the Joining Performance of Fiber-Reinforced Composite With Pa66 Nanofibers Produced by the Electrospinning Method(The Composites and Advanced Materials Expo (CAMX), 2023) Esenoğlu,G.; İriş,M.E.; Dehneliler,S.; Tanoğlu,M.; Barışık,M.; Aktaş,E.In this study, electrospun polyamide-6.6 (PA 66) nanofibers were added to bond surfaces to improve the bond strength of a structural fiber-reinforced composite. For this purpose, the nanofiber were coated on the UD carbon/epoxy prepregs. Composite laminates were fabricated using the autoclave method, employing carbon/epoxy prepregs with/without PA66 nanofiber incorporation of bond region. A single lap shear, Charpy impact energy and Mode-I fracture toughness tests were applied to the reference and PA 66 coated samples to examine the effects of PA 66 nanofibers on the mechanical properties of the joint region of the composites. The morphology and fracture modes of the nanofibers were investigated by scanning electron microscopy (SEM). The thermal properties of PA66 nanofibers were investigated by the differential scanning calorimetry (DSC) method. It was found that the PA 66 nanofibers coated on the prepreg surfaces by electrospinning are very effective in improving the strength of composite joints. The results revealed that single lap shear and Charpy impact strength values of the composite joint are increased by about 79% and 24%, respectively, by coating PA 66 nanofibers to the joint region. The results also showed that by using PA 66 nanofibers, Mode-I fracture toughness value is improved by about 107% and Tg was not affected. Copyright © 2023. Used by CAMX - The Composites and Advanced Materials Expo with permission.Article Citation - WoS: 40Citation - Scopus: 37Investigation of Interlayer Hybridization Effect on Burst Pressure Performance of Composite Overwrapped Pressure Vessels With Load-Sharing Metallic Liner(SAGE Publications, 2020) Kangal, Serkan; Kartav, Osman; Tanoğlu, Metin; Aktaş, Engin; Artem, Hatice SeçilIn this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [+/- 11 degrees/90 degrees(2)](3) to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic-plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.Article Citation - WoS: 97Citation - Scopus: 110Effect of Polyamide-6,6 (pa 66) Nonwoven Veils on the Mechanical Performance of Carbon Fiber/Epoxy Composites(Elsevier Ltd., 2018) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, EnginIn this study, carbon fiber/epoxy (CF/EP) composites were interleaved with polyamide-6,6 (PA 66) nonwoven veils at two different areal weight densities (17 and 50 gsm) to improve their delamination resistance against Mode-I loading. Mode-I fracture toughness (DCB), tensile, open hole tensile (OHT), flexural, compression, short beam shear (ILSS) and Charpy-impact tests were performed on the reference and PA 66 interleaved composite specimens. The DCB test results showed that the initiation and propagation Mode-I fracture toughness values of the composites were significantly improved by 84 and 171% using PA 66-17 gsm veils respectively, as compared to reference laminates. The use of denser PA 66-50 gsm veils in the interlaminar region led to higher improvement in fracture toughness values (349% for initiation and 718% for propagation) due to the higher amount of veil fibers involved in fiber bridging toughening mechanism. The incorporation of PA 66-50 gsm nonwoven veils also increased the ILSS and Charpy impact strength of the composites by 25 and 15%, respectively. On the other hand, the PA 66 veils reduced in-plane mechanical properties of CF/EP composites due to lower carbon fiber volume fraction and increased thickness.Conference Object Roc Curves for Evaluating Sensor Performance as Low Energy Impacts Damage a Composite Wing(DEStech Publications Inc., 2009) Aktaş, Engin; Seaver, M.Eight fiber Bragg gratings and 3 ICP accelerometers attached to the upper surface of a foam core composite wing (1320 mm X 152.4 mm X 13.4 mm) were used to record the wing's response to broad band (0 - 1500 Hz) Gaussian excitation following a series of low energy (-6.5 J) impacts to the surface of the wing. For each damage level, at least 15 measurements were made over a period of three days to enable a statistical evaluation of each sensor's performance. Damage detection relied on measuring nonlinearity in the response data using a second order correlation metric called the Bicoherence. The amplitudes of any peaks seen in the Bicoherence were compared with thresholds determined from the variance in the off diagonal terms in the Bicoherence measurement. This approach allows the evaluation of both the probability of detection (POD) and the probability of false alarms (PFA) for each measurement without the need for a healthy baseline. The results show that all eight FBGs out perform the accelerometers and that one FBG in particular is more sensitive to nonlinearity than the others. The measurement sensitivity of the Bicoherence is also compared with static tip deflection measurements.Article Citation - WoS: 16Citation - Scopus: 24Developing Polymer Composite-Based Leaf Spring Systems for Automotive Industry(Walter de Gruyter GmbH, 2018) Öztoprak, Nahit; Güneş, Mehmet Deniz; Tanoğlu, Metin; Aktaş, Engin; Eğilmez, Oğuz Özgür; Şenocak, Çiler; Kulaç, GedizComposite-based mono-leaf spring systems were designed and manufactured to replace existing mono-leaf metal leaf spring in a light commercial vehicle. In this study, experimentally obtained mechanical properties of different fiber-reinforced polymer materials are presented first, followed by the description of the finite element analytical model created in Abaqus 6.12-1 (Dassault Systemes Simulia Corp., RI, US) using the obtained properties. The results from the finite element analysis are presented next and compared with actual size experimental tests conducted on manufactured prototypes. The results demonstrated that the reinforcement type and orientation dramatically influenced the spring rate. The prototypes showed significant weight reduction of about 80% with improved mechanical properties. The hybrid composite systems can be utilized for composite-based leaf springs with considerable mechanical performance.Article Citation - WoS: 1Citation - Scopus: 1Estimation of Mechanical Properties of Limestone Using Regression Analyses and Ann(Foundation Cement, Lime, Concrete, 2012) Teomete, Egemen; Tayfur, Gökmen; Aktaş, EnginEstimation of mechanical properties of rocks is important for researchers and field engineers working in cement and concrete industry. Limestone is used in cement production. In this study, Schmidt hammer, ultrasonic pulse velocity, porosity, uniaxial compression and indirect tension tests were conducted on limestone obtained from a historical structure. Regression analyses were used to develop models relating mechanical properties of limestone. Artificial Neural Network (ANN) was performed to determine the mechanical properties. The performance of regression models and ANN were compared by existing models in the literature. The results showed that the regression models and ANN yield satisfactory performance with minimum error. The regression models between tensile strength and wave velocity, tensile strength and porosity, wave velocity and porosity have been developed for the first time in literature. The ANN is used for the first time to estimate the mechanical properties of limestone. The use of separate training and testing sets in the regression analyses of mechanical properties of limestone is conducted for the first time. The models developed in this study can be used by researchers and field engineers to relate the mechanical properties of limestone.Article Citation - WoS: 39Citation - Scopus: 40Mode-I Fracture Toughness of Carbon Fiber/Epoxy Composites Interleaved by Aramid Nonwoven Veils(Techno Press, 2019) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, EnginIn this study, carbon fiber/epoxy (CF/EP) composites were interleaved with aramid nonwoven veils with an areal weight density of 8.5 g/m(2) to improve their Mode-I fracture toughness. The control and aramid interleaved CF/EP composite laminates were manufactured by VARTM in a [0]4 configuration. Tensile, three-point bending, compression, interlaminar shear, Charpy impact and Mode-I (DCB) fracture toughness values were determined to evaluate the effects of aramid nonwoven fabrics on the mechanical performance of the CF/EP composites. Thermomechanical behavior of the specimens was investigated by Dynamic Mechanical Analysis (DMA). The results showed that the propagation Mode-I fracture toughness values of CF/EP composites can be significantly improved (by about 72%) using aramid nonwoven fabrics. It was found that the main extrinsic toughening mechanism is aramid microfiber bridging acting behind the crack-tip. The incorporation of these nonwovens also increased interlaminar shear and Charpy impact strength by 10 and 16.5%, respectively. Moreover, it was revealed that the damping ability of the composites increased with the incorporation of aramid nonwoven fabrics in the interlaminar region of composites. On the other hand, they caused a reduction in in-plane mechanical properties due to the reduced carbon fiber volume fraction, increased thickness and void formation in the composites.Article Citation - WoS: 3Citation - Scopus: 3Structural Vulnerability of Ancient Dry Masonry Towers Under Lateral Loading(Elsevier, 2020) Gençer, Funda; Hamamcıoğlu Turan, Mine; Turan, Mine; Aktaş, Engin; Aktaş, EnginUnderstanding how the original characteristics contribute to the structural behaviour of antique structures should be the initial stage of planning for conservation work. This study aims to identify the structural behaviour of dry masonry towers under lateral loadings, so that the decision-making process when determining their restoration can be adequately supported. Dry masonry towers in ancient Caria, Pamphylia, and Cilicia Regions are examined. Each of these three areas have very different seismic characteristics. A hypothetical testing process was designed by combining different characteristics from each of the towers. As a result, the characteristics affecting the structural resistance were determined as; the staggering ratio, the stone depth, the ratio between block length and height, the proportional relationship between height and length, the area, number and position of openings, and the distribution of header stones. These characteristics all interact together to determine the failure mechanism; so, understanding this interaction is critical when considering conservation. © 2020 Elsevier LtdArticle Citation - WoS: 2Citation - Scopus: 2Reliability of Corroded Steel Members Subjected To Elastic Lateral Torsional Buckling(Korean Society of Steel Construction, 2021) Uzun, Ertuğrul Türker; Aktaş, EnginStructural steel members are subjected to corrosion due to environmental condition. As a result, there is decreasing in the cross-section properties of the member. This causes different stability problems and reduction in the load carrying capacity of members. Then, the probability of failure, P-f increases due to corrosion. The need arises to determine expected level of safety for such members and systems. Besides, reliability of the steel structure is also effected by the structural stability problems that result decreasing in the resistance. Lateral torsional buckling is one of the most encountered problems in steel members and affected by the critical moment which is a function of lateral and torsional stiffness. Critical moment depends on the material properties, boundary conditions, unbraced length, load pattern, and the member's cross section. Under the corrosion, it is inevitable to observe changing in some of properties. In this study, a damage model to determine the reliability of a corroded I-shape steel member under linear moment gradient is developed considering corrosion exposure time. Uniform and varying thickness loss models are considered to show the corrosion effect. Influence of environmental condition on the load carrying capacity of the members is considered and their effects on member design is evaluated. As a result, it is concluded that load carrying capacity of steel members degrades and safety of them adversely effected. With presented formulas, it is ensured that the load carrying capacity and reliability indices of the steel members can be calculated practically under the examined situationsMaster Thesis Structural Model Besed Root Cause Investigation of Damage in Urla Helvacılar Mosque and a Proposal for Strengthening(Izmir Institute of Technology, 2019) Narin Güzel, Ceren; Kul Özdemir, Fatma Nurşen; Aktaş, EnginThe period when small independent beyliks (principalities) were founded in Anatolia in the 13th century is called the principalities period. The process of creating a new architectural style in Western Anatolia, as well as the works-built marks an important milestone in this period, which is defined as a transition period between the Seljuk architecture and the Ottoman architecture. The Aydın Dynasty, one of the important principalities of western Anatolia, had its capital at Birgi from 1308 to 1426. The dynasty is known for with its economic and political power and the important works it left behind. Helvacılar Mosque is one of the important works of the Aydın Dynasty, which was built in the 15th century and survives today. It is also an outstanding example to understand the single-domed mosque typology in western Anatolia. Helvacılar Mosque, located in the Kuşcular Neighborhood of the Urla District, is today derelict and abandoned. Heavy structural damage in the structure poses a grave risk for the structure to survive. This study compared and discovered the similarities and differences between Helvacılar Mosque and the similar-period structures situated in Urla and identified the architectural and structural characteristics of the structure with the aid of measured drawing projects. This study used a combination of architectural restoration and structural engineering. For Helvacılar Mosque, the study carried out the self-weight analysis, modal analysis, settlement analysis, response spectrum analysis, time history analysis using three real earthquake records in a finite element model. The aim of engineering research is to identify the present causes of damages in the structure. With the help of finite element analysis, the study put forward the essential repair and strengthening methods for Helvacılar Mosque to repair the damages observed in the structure, strengthen the structure, and obviate the causes of the damages based on the intervention methods offered in the guideline titled Earthquake Risk Management of Historical Structures issued by the General Directorate of Foundations.