WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 2The Effect of the Temperature of Heat Treatment Process and the Concentration and Duration of Acid Leaching on the Size and Crystallinity of Nano-Silica Powders Formed by the Dissociation of Natural Diatom Frustule(American Scientific Publishers, 2022) Ülker, Sevkan; Güden, MustafaThe present study focused on the processing of nano-silica powders in varying sizes and crystallinities through IP: 846247.10 On: Wed, 14 Dec 2022 07:29:25 heat treatment (900-1200 degrees C), hydrofluoric acid leaching (1-7 N), and ball milling (1 h, 500 rpm) of natural Copyright American Scentfic P blishers diatom frustules. The starting natural frustules were determined to be composed of amorphous silica (88%) Delivered by Ingenta and quartz. The partially ordered crystalline low-quartz and or precursor to low-cristobalite started to form at-900 degrees C. As the heat treatment temperature increased, the crystallinity of the frustules increased from 9.3% at 25 degrees C to 46% at 1200 degrees C. Applying a ball milling reduced the mean particle sizes of the as-received and heat-treated frustules from 15.6-13.7 mu m to 7.2-6.7 mu m, respectively. Acid leaching of the as-received and heat-treated frustules resulted in a further increase in the crystallinity. Furthermore, a ball milling applied after an acid leaching was very effective in reducing the particle size of the as-received and heat-treated frustules. The mean particle size of the acid-leached frustules decreased to 774-547 nm with a crystallinity varying between 12 and 48% after ball milling. A partially dissolved amorphous phase was observed in between crystalline silica grains after acid leaching, which resulted in a rapid fracture/separation of the frustules in ball milling.Conference Object Citation - WoS: 1Citation - Scopus: 1Numerical and Experimental Studies of High Strain Rate Mechanical Behavior of E-glass/Polyester Composite Laminates(The American Society of Mechanical Engineers(ASME), 2010) Tunusoğlu, Gözde; Taşdemirci, Alper; Güden, Mustafa; Hall, Ian W.Quasi-static ∼10-3 s-1) and high strain rate (∼850 s-1) compression behavior of an E-glass/polyester composite was determined in the through-thickness and in-plane directions. In both directions, modulus and failure strength increased with increasing strain rate. Higher strain rate sensitivity for both elastic modulus and failure strength was observed in the in-plane direction. A numerical model was developed to investigate the compressive deformation and fracture of an E-glass/polyester composite. Excellent agreement was demonstrated for the case of high strain rate loading. Also, the fracture geometries were successfully predicted with the numerical model.Conference Object Citation - WoS: 3Citation - Scopus: 3Numerical Approach To Design Process of Armored Vehicles(The American Society of Mechanical Engineers(ASME), 2010) Erdik, Atıl; Kılıç, Namık; Güden, Mustafa; Taşdemirci, AlperToday, it is imperative that armored vehicles need advanced protection kits against anti-symmetric threats more than before. The primary goal of this study was to assess benefits of explicit hydrocodes for mine protection resistance of armored vehicles. An analysis of an armored vehicle under blast loading caused by high explosive (HE) detonation is presented with comparison to a full-scale test. The problem was examined using LS-DYNA which is an explicit non-linear finite element code. Multi Material Arbitrary Lagrangian Eulerian (MM-ALE) Fluid Structure Interaction Method was selected to model the explosion domain so as to observe advancing of the shock wave in the compressed air and to investigate the effects of blast on the vehicle structure after explosion. Johnson-Cook constitutive material model, Jones-Wilkins-Lee (JWL) and Linear Polynomial equation of states were used for the problem. Results show that numerical analysis was in good agreement with the experimental result.Article Citation - WoS: 24Citation - Scopus: 26Split Hopkinson Pressure Bar Compression Testing of an Aluminum Alloy: Effect of Lubricant Type(Chapman & Hall, 2003) Hall, Ian W.; Güden, MustafaThe Split Hopkinson Pressure Bar (SHPB), or Kolsky Bar, is widely used for studying the dynamic mechanical properties of metals and other materials. A cylindrical specimen is sandwiched between the incident and transmitter bars, Fig. 1, and a constant amplitude elastic wave is generated by the striker bar. Strain gages mounted on the incident and transmitter bars allow the compressive stress-strain response of the specimen to be established using uniaxial elastic wave theory [1]. A more detailed overview of SHPB testing is found in [2]. Lubricant is usually applied to the interfaces because the presence of any frictional effect on the specimen surfaces forms a multiaxial stress-state and invalidates one of the most important assumptions of the SHPB analysis, namely, a uniaxial stress state. This paper quantifies the effect for an aluminum alloy.Book Part Citation - WoS: 21Citation - Scopus: 24Metals Foams for Biomedical Applications: Processing and Mechanical Properties(Springer, 2004) Güden, Mustafa; Çelik, Emrah; Çetiner, Sinan; Aydın, AlptekinOptimized structures found in nature can be sometimes imitated in engineering structures. The recent interest in functionally graded metallic materials makes bone structures interesting because bones are naturally functionally graded1. The cellular structure of foam metals (Fig.1) is very similar to that of the cancellous bone; therefore, these metals can be considered as potential candidates for future implant applications if porosity level, size and shape, strength and biocompatibility aspects satisfy the design specifications of implants. Foam metals based on biocompatible metallic materials (e.g. Ti and Ti-6A1-4V) are expected to provide better interaction with bone. This is mainly due to higher degree of bone growth into porous surfaces and higher degree of body fluid transport through three-dimensional interconnected array of pores2 (open cell foam), leading to better interlocking between implant and bone and hence reducing or avoiding the well-known implant losening. Furthermore, the elastic modulus of foam metals can be easily tailored with porosity level to match that of natural bone, leading to a better performance by avoiding the high degree of elastic mismatch which currently exists between conventional solid metallic implants and bone.Article Citation - WoS: 5Citation - Scopus: 7High Strain Rate Testing of a Unidirectionally Reinforced Graphite Epoxy Composite(Chapman & Hall, 2001) Hall, Ian W.; Güden, MustafaSince accurate, reproducible methods of testing polymer composites are not very well developed or standardized, this research forms part of a program to gain a better understanding of the mechanical properties and failure mechanisms of polymer composites at high strain rates. Since failure modes differ markedly depending on fiber architecture, orientation, fiber/matrix combination and so forth, these initial tests were carried out using a simple unidirectionally reinforced composite. Beginning with testing in the longitudinal and transverse directions, reported here, future experiments are being carried out to determine how the high strain rate properties vary with angle of testing, and then move on to other simple fiber lay-ups, ±90◦, ±45◦, etc.Article Citation - WoS: 25Citation - Scopus: 28High Strain Rate Deformation Behavior of a Continuous Fiber Reinforced Aluminum Metal Matrix Composite(Elsevier Ltd., 2000) Güden, Mustafa; Hall, Ian W.An aluminum metal matrix composite reinforced with continuous unidirectional α-Al2O3 fibers has been compression tested at quasi-static and dynamic strain rates. In the transverse direction, the composite showed increased flow stress and maximum stress within the studied strain rate regime, 10−3 to 3500 s−1. The strain rate sensitivity of the flow stress in this direction was found to be similar to that of a similar, but unreinforced, alloy determined from previous work. In the longitudinal direction, the maximum stress of the composite increased with increasing strain rate within the range 10−5 to 700 s−1. The strain rate dependent maximum stress in this direction was described by the strain rate dependent fiber buckling stress.Article Citation - WoS: 4Citation - Scopus: 5Improving the Energy Absorption of Closed Cell Aluminum Foams(Chapman & Hall, 2002) Greene, S. A.; Hall, Ian W.; Güden, MustafaClosed cell aluminum foams have received much recent attention as energy absorbing materials on account of their ability to undergo extensive deformation at a relatively low stress called the plateau stress. Several studies describe the improvements in energy absorption to be obtained, relative to their empty counterparts, when foam filled tubes are crushed either quasi-statically or dynamically [1–4]. Al foams are also of possible interest for ballistic applications because they present a very large acoustic impedance mismatch with common armor materials, offering the possibility of being able to modify theway in which elasticwaves travel through multi-component armor.Conference Object Citation - WoS: 11Citation - Scopus: 18Experimental and Numerical Investigation of High Strain Rate Mechanical Behavior of a [0/45 - 45] Quadriaxial E-glass/Polyester Composite(Elsevier Ltd., 2011) Taşdemirci, Alper; Kara, Ali; Turan, Ali Kıvanç; Tunusoğlu, Gözde; Güden, Mustafa; Hall, Ian W.Quasi-static (10−3–10−1 s−1) and high strain rate (∼900 s−1) compression behavior of an E-Glass fiber woven fabric reinforced Polyester matrix composites was investigated by using a Shimadzu AG-I testing machine and a Split Hopkinson Pressure Bar apparatus in the Dynamic Testing and Modeling Laboratory of Izmir Institute of Technology. During the experiments, a high speed camera was used to determine deformation behavior. In both directions, modulus and failure strength increased with increasing strain rate. Higher strain rate sensitivity for both elastic modulus and failure strength was observed in the in-plane direction. Based upon these experimental data, a numerical model was developed using the commercial explicit finite element code LS-DYNA to investigate compressive deformation and damage behavior of composites. Excellent agreement was demonstrated for the case of high strain rate loading. Also, the fracture geometries were successfully predicted with the numerical model.Article Testing Corrosion Rates on Steel Piping in Geothermal District Heating(National Association of Corrosion Engineers, 2008) İnce, Umut; Toksoy, Macit; Güden, MustafaThe corrosion behavior of St-37 pipeline carbon steel (CS) in a geothermal district heating system was tested at two different fluid velocities. An experimental set-up, directly connected the the end of the transmission line of a geothermal well, was used to assess the corrosion of St-37 steel tensile test coupons prepared in accordance with ASTM E8 in geothermal fluid. The geothermal fluid entered the set-up with a relatively low velocity, 0.02 m/s, and then injected into the well with a relatively high fluid velocity, 9.6 m/s. It was observed that while the uniform corrosion rates were relatively low, pitting corrosion rate, mainly driven by the sulfate-reducing bacteria (SRB) activity, was relatively high and more pronounced at low fluid velocities. St-37 steel material is prone to the pitting type corrosion, thus a biocide chemical addition and the fluid velocity of 2 to 3 m/s in transmission line were recommended to reduce SRB activity to reduce the pitting corrosion rate.