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: 1Sol-Derived Hydroxyapatite Ddip-Coating of a Porous Ti6al4v Powder Compact(Al-Farabi Kazakh State National University, 2009) Altındiş, Mustafa; Güden, Mustafa; Ni, ChaoyingA sintered porous Ti6Al4V powder compact with a mean pore size of 63 µm and an average porosity of 37±1% was dip-coated at soaking times varying between 1- and 5-minute using a sol-derived calcium Hydrooxyapatite (HA) powder. The coated compacts were heat-treated at 840 °C. The coating thickness was found to increase with increasing soaking time, from 1.87 µm at 1-minute soaking to 9 µm at 5-minute soaking on the average. It was shown that at increasing soaking times, the originally open pores started to close, while at low soaking times the Ti6Al4V particles were partially coated. The coating layer was shown to be nano porous and the depth of coating was observed to be relatively shallow: only few particles near the compact surface were HA-coated.Conference Object Citation - WoS: 8Citation - Scopus: 12Mechanical Properties of Hydroxyapatite Composites Reinforced With Hydroxyapatite Whiskers(Trans Tech Publications, 2004) Şimşek, Deniz; Çiftçioğlu, Rukiye; Güden, Mustafa; Çiftçioğlu, Muhsin; Harsa, Hayriye ŞebnemSintering and mechanical behavior of pure and hydroxyapatite (HA) whisker reinforced HA composites were investigated in this work. Pure and composite samples were prepared by using a commercial powder and whiskers prepared by molten salt synthesis. The dry-pressed samples were sintered in the 800 and 1300°C range. The effect of whisker-addition on the mechanical properties of HA was investigated through compression and hardness testing. Compressive strength and fracture strain were observed to increase by the addition of whiskers.Article Citation - WoS: 71Citation - Scopus: 78The Strengthening Effect of Polystyrene Foam Filling in Aluminum Thin-Walled Cylindrical Tubes(Elsevier Ltd., 2005) Toksoy, Ahmet Kaan; Güden, MustafaThe strengthening effect of foam filling in thin-walled circular tubes, deforming in diamond and concertina modes, was investigated in polystyrene foam filled aluminum tubes. Empty tubes of two different diameters (16 and 25 mm) deformed in diamond mode, while foam filling changed the deformation mode into concertina in 25 mm tube due to thickening effect of foam filling. The strengthening coefficient in concertina mode was found around unity, while in diamond mode it was greater than unity. In concertina mode, foam and tube were observed to deform independently. However, in diamond mode, foam was compressed in between the folds, leading to a higher strengthening coefficient. The effects of deformation rate and the use adhesive on the average crushing loads of the filled tubes were also determined.Article Citation - WoS: 12Citation - Scopus: 12The Effect of Strain Rate on the Compressive Deformation Behavior of a Sintered Ti6al4v Powder Compact(Elsevier Ltd., 2008) Taşdemirci, Alper; Hızal, Alpay; Altındiş, Mustafa; Hall, Ian W.; Güden, MustafaThe high strain rate (220–550 s−1) and quasi-static (0.0016 s−1) compression deformation behavior of a sintered Ti6Al4V powder compact was investigated. The compact was prepared using atomized spherical particles (100–200 μm) and contained 38 ± 1% porosity. The deformation sequences of the tested samples were further recorded by high speed camera and analyzed as a function of strain. The failure of the compact, which was found to be similar in the studied high strain rate and quasi-static strain rate testing regimes, occurs through particle decohesion along the surface of the two cones in a ductile (dimpled) mode consisting of void initiation and growth and by void coalescence in the interparticle bond region. The effect of strain rate was to increase the flow stress and compressive strength of the compact while the critical strain corresponding to the maximum stress was shown to be strain rate independent.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.Article Citation - WoS: 41Citation - Scopus: 38Simulation of the Strain Rate Sensitive Flow Behavior of Sic-Particulate Reinforced Aluminum Metal Matrix Composites(Elsevier Ltd., 2008) Tirtom, İsmail; Güden, Mustafa; Yıldız, HasanStrain rate dependent compression mechanical behavior of an SiC-particulate reinforced Al (2024-O) metal matrix composite (MMC) with different particle volume fractions was numerically investigated at various strain rates. Calculations were performed using axisymmetric finite element unit cell model, in which an elastic SiC particle was embedded inside a strain rate sensitive viscoplastic Al matrix. Stress–strain curves of Al matrix material were derived from Split Hopkinson Pressure Bar experiments at various strain rates and used as inputs in the FEM model. Numerically computed stress–strain curves and strain rate sensitivity were compared with those of experiments for a 15% SiC-particulate reinforced MMC. Computed strain rate sensitivity of the MMC was found to be higher than that of the matrix alloy and increased with increasing strain contrary to the strain independent matrix strain rate sensitivity. The strain rate sensitivity of the MMC was also found to increase with increasing particle volume fraction at the same particle size. Finally, several possible reasons including assumptions used in the model, adiabatic heating, microstructural variations between the composite matrix and matrix alloy, particle shape and distribution and damage accumulation for the small discrepancy found between computed and experimental stress–strain curves and strain rate sensitivity of the composite were discussed.Article Citation - WoS: 54Citation - Scopus: 62Sic-Particulate Aluminum Composite Foams Produced by Powder Compacts: Foaming and Compression Behavior(Springer Verlag, 2003) Elbir, Semih; Yılmaz, Selahattin; Toksoy, Ahmet Kaan; Güden, Mustafa; Hall, Ian W.The foaming behavior of SiC-particulate (8.6% by volume) aluminum composite powder compacts contained Titanium Hydride blowing agent was investigated by heating above the melting temperature (750°C) in a pre-heated furnace. Aluminum powder compacts were also prepared and foamed using similar compaction and foaming parameters in order to determine the effect of SiC-particulate addition on foaming and compression behavior. The linear expansions of the compacts at various furnace holding times were ex situ determined. Optical and scanning electron microscopy techniques were used to characterize prepared and deformed foams microstructures. The SiC-particulate addition was found to increase the linear expansion and reduce the extent of the liquid metal drainage and cell coarsening of the aluminum compacts. The composite foam samples also showed higher compressive stresses, but a more brittle behavior as compared with aluminum foams.Article Citation - WoS: 55Citation - Scopus: 61Sic-Particulate Aluminum Composite Foams Produced From Powder Compacts: Foaming and Compression Behavior(Springer Verlag, 2006) Güden, Mustafa; Yüksel, SinanThe foaming behavior of SiC-particulate (SiCp) aluminum composite powder compacts containing titanium hydride blowing agent was investigated by heating to 750°C in a pre-heated furnace. Aluminum powder compacts were also prepared and foamed using similar compaction and foaming parameters in order to determine the effect of SiCp-addition on the foaming and compression behavior. The SiCp-addition (10 wt%) was found to increase the linear expansion of the Al powder compacts presumably by increasing the surface as well as the bulk viscosities. The compression tests conducted on Al and 10 and 20% SiCp foams further showed a more brittle compression behavior of SiCp/Al foams as compared with Al foams. The collapse stresses of Al and 10% SiCp/Al foams were also predicted using the equations developed for the open and closed cell foams. Predictions have shown that Al foam samples behaved similar to open cell foams, while 10% SiCp/Al foam collapse stress values were found between those of open and closed cell foams, biasing towards those of the open cell foams.Article Citation - WoS: 123Citation - Scopus: 139Quasi-Static Axial Crushing of Extruded Polystyrene Foam-Filled Thin-Walled Aluminum Tubes: Experimental and Numerical Analysis(Elsevier Ltd., 2006) Aktay, Levent; Toksoy, Ahmet Kaan; Güden, MustafaThe experimental and numerical quasi-static crushing responses of extruded closed cell polystyrene foam-filled thin-walled aluminum tubes were investigated. The numerical crash analysis of empty and foam-filled tubes was performed using the explicit finite element code PAM-CRASH™. Satisfactory agreements were generally achieved between the finite element model and experimental deformed shapes, load–displacements, fold lengths and specific energy absorptions. The model and experiments have also highlighted the several effects of foam filling on the crushing of thin-walled tubes. The energy absorptions in foam-filled tubes were further shown to be higher than the sum of the energy absorptions of empty tube (alone) and filler (alone).Article Citation - WoS: 59Citation - Scopus: 68Quasi-Static Axial Compression Behavior of Constraint Hexagonal and Square-Packed Empty and Aluminum Foam-Filled Aluminum Multi-Tubes(Elsevier Ltd., 2006) Güden, Mustafa; Kavi, HalitThe axial crushing behavior of empty and Al close-cell foam-filled single Al tubes and Al multi-tube designs (hexagonal and square) were investigated through quasi-static compression testing. The effects of foam filling on the deformation mode and the crushing and average crushing loads of single tubes and multi-tube designs were determined. The foam filling was found to shift the deformation mode of empty single tube and empty multi-tube designs from diamond into concertina. In multi-tube designs the constraint effects and the frictional forces were found to increase the average crushing loads over those of single tubes. It was also found that foam filling induced a higher strengthening coefficient in multi-tube than single tubes. Although foam filling increased the energy absorption in single tubes and multi-tube designs, it was not effective in increasing the specific absorbed energy over that of the empty tubes. However, multi-tube designs were found to be energetically more effective than single tubes at similar foam-filler densities, proving a higher interaction effect in multi-tube designs.