Person: YAZICI, MURAT
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YAZICI
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MURAT
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Publication Experimental investigation of 3d-printed auxetic core sandwich structures under quasi-static and dynamic compression and bending loads(Sage Publications Ltd, 2022-03-27) Türkoğlu, I. Kurşad; Kasım, Hasan; Yazıcı, Murat; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Ana Bilim Dalı; 0000-0002-3024-5207; 0000-0002-8720-7594; M-4741-2017Auxiliary metamaterials designed according to the Negative Poisson's Ratio (NPR) property are exciting structures due to their high impact strength, impact energy absorption abilities, and different damage mechanisms. These good mechanical features are suitable for aviation, automotive, and protective construction applications. These structures, whose most significant disadvantages are production difficulties, have become easier to produce with the development of 3D production technology and have been the subject of many studies in recent years. In this presented study, two conventional core geometries and three different auxetic geometries, commonly used in sandwich structures, were designed and produced with 3D printer technology. The strength and energy absorption capabilities of prototype sandwich structures investigated experimentally under bending loads with static and dynamic compression. Except for the re-entrant (RE) type core, the auxetic core foam sandwich structures demonstrate higher rigidity and load-carrying capacity than classical sinusoidal corrugated (SC) core and honeycomb (HC) core sandwich structures under both quasistatic and impact-loaded compression and three-point bending experiments. Double arrowhead (DAH) and tetrachiral (TC) auxetic cores outperformed honeycomb core in terms of specific quasistatic and impact load-bearing performance under compression by 1.5 +/- 0.25 times. In three-point bending experiments under both quasi-static and impact loading conditions, the load-carrying capacity of the double arrowhead and tetrachiral auxetic cores was found to be more than 1,86 +/- 0.38 times that of the honeycomb core sandwich panels.Publication Investigation of the crack propagation in the graphene/ synthetic rubber nanocomposite materials with DIC technique(Budapest Univ Technology Economics, 2022-01-27) Kasım, Hasan; Aldeen, Ahmad Naser; Onat, Adem; Saraç, İsmail; Engin, Barış; Yazıcı, Murat; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-8720-7594 ; M-4741-2017This study investigated the crack propagation behavior of the graphene-reinforced synthetic rubber matrix nanocomposite materials. Graphene-filled rubber conductive nanocomposites developed within the scope of this study were obtained in two stages using mechanical mixers. The relationship between crack propagation and electrical resistance change was investigated using single-edge notched specimens in a tensile tester. Digital image correlation (DIC) technique was used to observe the crack resistance function depending on the local strain distribution. The results from the tests were evaluated to define the relationship between the crack length, the amount of conductive filler, and the change in electrical resistance. The sharp edges of the graphene nanoplatelets negatively affected the fracture resistance of the samples. In addition, it was observed that even at low strain values, gaps were formed in the areas close to the crack tip. The three-dimensional transmission network formed by graphene nanoplatelets dispersed in the matrix improved the electrical conductivity properties of the nanocomposites, so the relationship between crack propagation and electrical resistance change was determined.Publication Sound insulation performance of honeycomb core aluminum sandwich panels with flexible epoxy-based foam infill(Elsevier Sci Ltd, 2023-05-11) Boztoprak, Yalçın; Ünal, Merve; Özada, Çağatay; Kuzu, Eslem; Özer, Hakkı; Ergin, Furkan; Yazıcı, Murat; Ünal, Merve; Özada, Çağatay; Kuzu, Eslem; ÖZER, HAKKI; Ergin, Furkan; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0003-1714-7394; 0000-0003-1503-1232; 0000-0002-8720-7594; M-4741-2017; AAG-9987-2021; AAC-5342-2021; FFS-9528-2022; FOL-7608-2022; IVA-3471-2023The most distinctive features of sound insulation structures are their flexibility and porosity. Therefore, the flexible epoxy matrix material was made cellular using a suitable foaming agent. In addition, hollow glass mi-crospheres (HGMs) were added to the epoxy matrix. Thus, the sound wave refraction was increased by obtaining cavities in the cell walls. Structures with different densities and voids were created by changing the ratios of the filling material and foaming agents used in the sandwich. An aluminum (Al) honeycomb was used to protect the insulation materials' structural integrity and ensure the homogeneous distribution of sound waves. The effect of density differences on sound insulation values was investigated. The mechanical properties of sandwich struc-tures were determined using compression and three-point bending tests. The distribution of the filler in the matrix was visualized using SEM. TGA, DSC, thermal conductivity, dielectric, and flammability tests were also performed to determine their thermal, electrical, and flammability properties. During the formation of cells in the flexible epoxy, the HGMs were positioned in the cell wall by internal gas pressure. Low-density structures performed better at low frequencies, while high-density structures at high frequencies.Publication A sandwich panel that autonomously repairs sudden large holes and defects for tankers and pipelines carrying hazardous matter(Sage Publications Ltd, 2022-04-12) Özer, Hakkı; Kuzu, Eslem; Özada, Çağatay; Ünal, Merve; Kasım, Hasan; Yazıcı, Murat; ÖZER, HAKKI; Kuzu, Eslem; Özada, Çağatay; Ünal, Merve; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0003-1503-1232; 0000-0002-8720-7594; AAC-5342-2021; M-4741-2017; AAG-9987-2021; FOL-7608-2022; FFS-9528-2022; AAG-9987-2021The self-healing of micro and macro cracks is vital for eliminating defects such as damage progression and loss of strength in structures. In this study, a polyurethane (PU) based geometrically self-healing sandwich structure was developed. The geometric healing agent, PU resin and activator, were filled into macrocapsules, and these capsules were filled into the Aluminum (Al) honeycomb cells. Self-healing of structural strength, large holes and cracks in developed sandwich structures were investigated by performing quasi-static compression and impact penetration tests. The sandwich structure with a self-healing capsules-filled core was damaged by subjecting it to quasi-static and penetration impact loads, and the healing agents in the broken capsules were mixed. The damage in the specimen was removed by geometric self-healing. Liquid and air permeability tests were applied to the PU foam used as a healing agent. No liquid permeability was observed in the structure. In addition, significant reductions in air permeability were obtained. Scanning electron microscope images were used to explore the characterization of the PU foam structure cells.Publication Investigation of the optimum vibration energy harvesting performance of electrospun PVDF/BaTiO₃ nanogenerator(Sage Publications Ltd, 2022-12-15) Güçlü, Harun; Kasım, Hasan; Yazıcı, Murat; GÜÇLÜ, HARUN; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-5679-313X; 0000-0002-8720-7594; Q-8738-2018; M-4741-2017The piezoelectric vibration energy harvesting performance of an electrospun poly(vinylidene fluoride) (PVDF)/Barium Titanate (BaTiO3) nanocomposite piezo polymer nanogenerator was investigated in this study. To obtain the highest piezoelectric output value, electrospinning was performed using four distinct solvent volume ratios of Acetone/Dimethylformamide (DMF) of 0:10, 2:8, 4:6, and 6:4 and three different PVDF weight percent polymer concentrations of 10, 15, and 20. Additionally, three distinct BaTiO3 addition weight percents of 5, 10, and 15 were investigated. The optimal concentration of PVDF (15 wt.%) was combined with a 6:4 volume ratio of Acetone/DMF to form a nanocomposite piezo polymer nanogenerator. The morphology and crystalline structure of PVDF and PVDF/BaTiO3 were analyzed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques. Nanocomposite piezo polymer nanogenerator was manufactured to harvest energy from vibration. A cantilever beam was developed without a tip mass type system for piezoelectric energy harvesting tests. The highest piezoelectric power output was obtained as 0.243 mu W (15 wt.% PVDF and 5 wt.% BaTiO3), Acetone/DMF (6:4 vol./vol.)) under 10 M Omega at the 15.7 Hz resonance frequency. The morphology of electrospun nanofibers has a significant impact on the piezoelectric performance of a nanocomposite piezo polymer nanogenerator at high-amplitude vibration.Publication A modular training project for vocational education and improvement in Turkey(Sage Publications Ltd, 2009-04-01) ARSLAN, RİDVAN; TEKİN, YÜCEL; Yazıcı, Murat; YAZICI, MURAT; Kuş, Abdil; KUŞ, ABDİL; Kaynak, Z. Gökay; Ziraat Fakültesi; 0000-0002-0111-6879; 0000-0002-8720-7594; J-3560-2012; M-4741-2017; V-1754-2018; AAG-9412-2021Various vocational training methods, most of which overlap with lifelong learning programmes, are being used to address the problem of unemployment - an issue of vital importance, especially for developing countries. This article examines the introduction of a modular certification project in Turkey supported by EU training funds. The objective of the project is to enable people who are unemployed to find work and people in employment to improve their professional skills and competences, and therefore their opportunities. The researchers observed the employment status and development of the 245 people who received a certificate. They found that 89% either had found work in a sector consistent with their training, thanks to their participation in the project, or had to taken up a different position in their current field of employment.Publication Development and characterization of self-healing microcapsules, and optimization of production parameters for microcapsule diameter and core content(Emerald Group Publishing Ltd, 2022-10-21) Özada, Çağatay; Ünal, Merve; Şahin, Eslem Kuzu; Özer, Hakkı; Motorcu, Ali Rıza; Yazıcı, Murat; Özada, Çağatay; Ünal, Merve; Şahin, Eslem Kuzu; ÖZER, HAKKI; YAZICI, MURAT; Fen Bilimleri Enstitüsü; Polimer Malzemeler Bölümü; 0000-0003-1503-1232; 0000-0002-8720-7594; M-4741-2017; AAG-9987-2021; AAC-5342-2021; GYE-4810-2022; FOL-7608-2022Purpose This study produced epoxy-filled urea-formaldehyde (UF) microcapsules (MCs) and T-403 amine MCs using the in situ technique. The Taguchi method was used to determine the effects of the control factors (temperature, stirring speed, core-shell ratio and surfactant concentration) affecting MCs' core diameter and core content and optimizing their optimum levels with a single criterion. Optimum control factor levels, which simultaneously provide maximum core diameter and core content of MCs, were determined by the PROMETHEE-GAIA multi-criteria optimization method. In addition, the optimized MC yield was analyzed by thermal camera images and compression test. Design/methodology/approach Microcracks in materials used for aerospace vehicles and automotive parts cause serious problems, so research on self-healing in materials science becomes critical. The damages caused by micro-cracks need to heal themselves quickly. The study has three aims: (1) production of self-healing MCs, mechanical and chemical characterization of produced MCs, (2) single-criteria and multi-criteria optimization of parameters providing maximum MC core diameter and core content, (3) investigation of self-healing property of produced MCs and evaluation. Firstly, MCs were produced to achieve these goals. Findings The optimized micro cures are buried in the epoxy matrix at different concentrations. Thermal camera images after damage indicate the presence of healing. An epoxy-amine MC consisting of a 10% by weight filled aluminum sandwich panel was prepared and subjected to a quasi-static compression test. It was determined that there is a strong bond between the UF shell and the epoxy resin. Originality/value The optimization of production factors has been realized to produce the most efficient MCs that heal using less expensive and more accessible methods.Publication Impact behavior of natural rubber based syntactic foam core sandwich structures(Walter, 2021-11-01) Güçlü, Harun; Kasım, Hasan; Türkoğlu, I. Kürşad; Can, Yucel; Yazıcı, Murat; GÜÇLÜ, HARUN; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-5679-313X; 0000-0002-8720-7594; M-4741-2017; Q-8738-2018In this study, the impact behavior of sandwich panels of natural rubberbased syntactic foam cores with aluminum face sheets was investigated experimentally and with the help of finite element analysis (FEA). Syntactic foam cores were produced byadding glass bubbles (GB) to the natural rubber (NR). Natural rubber was dissolved at room temperature with chemical solvents mixed with glass bubbles at 10, 20, and 30 weight percentages. Very low density (similar to 0.8 g x cm(-3)) and high compressible foams were obtained depending on the GB weight percentages. Aluminum face sheets and the NR/GB syntactic foam core developed were joined by adhesive bonding to produce sandwich beam specimens. The sandwich beams manufactured in this way were subjected to impact loading under three-point bending boundary conditions experimentally. The experimental results were compared with finite element simulation results under the same loading and boundary conditions. The damage mechanism of the sandwich panels devised were analyzed. According to the results, natural rubber containing an additive of 20 wt.-% GBs showed better impact resistance than the others.Publication A review of potassium sodium niobate and bismuth sodium titanate based lead free piezoceramics(Elsevier, 2022-03-16) Tokay, Onat; Yazıcı, Murat; Tokay, Onat; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendislik; 0000-0002-8720-7594; M-4741-2017; GMO-9026-2022The use of piezoelectric materials is on the rise with their applications as generators, sensors, actuators, and transducers for different purposes such as energy harvesting, strain sensor, active vibration reduction, ultrasonic sonar, distance meter, and distance meter other applications. After its discovery, PZT and lead-based piezoceramics are the main options for choosing a piezoelectric material since they have a high piezoelectric coefficient and high Curie temperature, d33 = 470-610 pC/N and TC= 300-400 degrees C respectively. However, the current trend of leaving toxic materials, which is backed up by legislative actions of countries, is leading to the replacement of lead-based piezo materials with lead-free piezo materials. Lead-free piezoceramics can be categorized into four groups which are bismuth sodium titanate (BNT) based, potassium sodium niobate (KNN) based, bismuth ferrite (BF) based, and barium titanate (BT) based; however. This study will focus on KNN and BNT based piezoceramics to narrow the scope in order to improve comprehensibility. BF and BT based piezoceramics will be left for the scope of another review study. Improving piezoelectric properties is possible for lead-free piezoceramics by using dopants, improving preparation technique, and achieving coexistence of multiple phases. BNT and KNN based piezoceramics can be prepared to achieve a piezoelectric coefficient as high as d33 = 300-450 pC/N with TC= 250-320 degrees C. In contrast, BNT based piezoceramics can be prepared to achieve a piezoelectric coefficient as high as d33 = 200-240 pC/N with TC= 300-320 degrees C. Lead-free piezoceramics with piezoelectric coefficient d33 > 400 pC/N and TC> 300 degrees C are contenders to replace lead-based piezoceramics, and there exist such KNN based piezoceramics.Publication Investigation of crack detection properties of elastomer-based nanocomposites under cyclic strain loading with graphene and carbon black interaction filler(Sage Publications Ltd, 2022-01-25) Kasım, Hasan; Boztoprak, Yalçın; Yazıcı, Murat; YAZICI, MURAT; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-8720-7594; M-4741-2017In this study, the synergistic effect created by adding Graphene (GE) nanoplatelets and carbon black (CB) fillers to the rubber matrix was used to determine the high stretchable sensor properties. GE and CB-filled rubber nanocomposite (HcN) strain sensors have been shown to detect and trace crack initiation and crack propagation of different sizes under cyclic loading. Tests were performed with four different crack sizes (0, 2.5, 5, and 10 mm) at five different strain levels (0%, 5%, 10%, 15%, and 20%) to determine the strain sensing performance of the specimens. The electrical response of HcNs under loading was measured with the four-point probe technique and recorded with a high-performance data acquisition system. The progression of external cracks created by scalpel on HcNs was examined by measuring electrical resistance changes caused by cyclic strain loading between 0% and 20%. The electrical response of 4 phr and 8 phr filled HcNs behaved qualitatively similar to each other, while 1 phr filled HcNs showed a significantly different response in terms of quality and quantity. In 4 phr GE-filled specimens, the resistance increase was changed steadily depending on the crack length, and unstable conditions occurred at 5 and 10 mm crack lengths at 1 and 8 phr GE filler ratios. The flexible and stretchable elastomer-based conductive strain sensing sensors, developed with the synergistic interaction of well-dispersed carbon-based fillers in the matrix, can detect and record damaged conditions caused by cyclic loading in many application areas.