Mechanics of Materials and Modeling
- Working Group
- Laboratories
- Publications
- Projects
| Prof. Dr. H. Seçil Artem | Res. Assist. Mehmet Yalçın Sırmalılar | |||
| Prof. Dr. Mustafa Güden | ||||
| Prof. Dr. Alper Taşdemirci |
Dynamic Test and Modelling Laboratory
Responsible Faculty Members
- A5 Building No:1/15
- +90 232 750 6624
Strength of Materials Laboratory
Responsible Faculty Member
- Mechanical Engineering Building (149)
- +90 232 750 6749
2011 |
Toksoy, A K; Guden, M The optimisation of the energy absorption of partially Al foam-filled commercial 1050H14 and 6061T4 Al crash boxes Journal Article INTERNATIONAL JOURNAL OF CRASHWORTHINESS, 16 (1), pp. 97-109, 2011, ISSN: 1358-8265. @article{ISI:000288960900009, title = {The optimisation of the energy absorption of partially Al foam-filled commercial 1050H14 and 6061T4 Al crash boxes}, author = {A K Toksoy and M Guden}, doi = {10.1080/13588265.2010.514774}, issn = {1358-8265}, year = {2011}, date = {2011-01-01}, journal = {INTERNATIONAL JOURNAL OF CRASHWORTHINESS}, volume = {16}, number = {1}, pages = {97-109}, abstract = {Partially Alulight and Hydro Al closed-cell foam-filled commercial 1050H14 Al and 6061T4 Al crash boxes were optimised using the response surface methodology in order to maximise specific energy absorption (SEA). The quasi-static crushing of empty and filled crash boxes was simulated using LS-DYNA, and the results were further confirmed with experimental quasi-static crushing testing of empty and Alulight foam-filled commercial 1050H14 Al crash boxes. Results showed that partial foam filling of commercial crash boxes increased both SEA and mean load because of foam filler axial and lateral deformation in between the progressing folds of the crash box. Within the studied constraint range of box mean load, box wall thickness and foam filler density, the optimised Alulight and Hydro foam-filled 1050H14 and 6061T4 crash boxes resulted in 26%-40% increase in total energy absorption as compared with empty crash boxes. Considering the same weight basis, the use of a higher yield strength box wall material and higher plateau stresses of Al foam filler resulted in higher energy absorptions in partial foam-filled boxes at relatively low displacements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Partially Alulight and Hydro Al closed-cell foam-filled commercial 1050H14 Al and 6061T4 Al crash boxes were optimised using the response surface methodology in order to maximise specific energy absorption (SEA). The quasi-static crushing of empty and filled crash boxes was simulated using LS-DYNA, and the results were further confirmed with experimental quasi-static crushing testing of empty and Alulight foam-filled commercial 1050H14 Al crash boxes. Results showed that partial foam filling of commercial crash boxes increased both SEA and mean load because of foam filler axial and lateral deformation in between the progressing folds of the crash box. Within the studied constraint range of box mean load, box wall thickness and foam filler density, the optimised Alulight and Hydro foam-filled 1050H14 and 6061T4 crash boxes resulted in 26%-40% increase in total energy absorption as compared with empty crash boxes. Considering the same weight basis, the use of a higher yield strength box wall material and higher plateau stresses of Al foam filler resulted in higher energy absorptions in partial foam-filled boxes at relatively low displacements. |
2010 |
Turkan, U; Guden, M The effect of nitric acid surface treatment on CaP deposition of Ti6Al4V open-cell foams in SBF solution Journal Article SURFACE & COATINGS TECHNOLOGY, 205 (7), pp. 1904-1916, 2010, ISSN: 0257-8972. @article{ISI:000286343100017, title = {The effect of nitric acid surface treatment on CaP deposition of Ti6Al4V open-cell foams in SBF solution}, author = {U Turkan and M Guden}, doi = {10.1016/j.surfcoat.2010.08.071}, issn = {0257-8972}, year = {2010}, date = {2010-12-01}, journal = {SURFACE & COATINGS TECHNOLOGY}, volume = {205}, number = {7}, pages = {1904-1916}, abstract = {The effect of nitric acid surface treatment on CaP deposition of an open-cell Ti6Al4V foam (60% porous and 300-500 m in pore size), prepared by means of the space holder method using 94 and 66 mu m average particle size powders, was investigated in a simulated body fluid (SBF) solution up to 14 days. Although, nitric acid surface treatment did not change the foam flat surface roughness values significantly, it increased surface area difference greatly by introducing nano scale undulations on the surface. The increased surface area difference was found to be more pronounced in smaller particle size foam samples. A continuous relatively thin CaP coating layer formed after 5 and 14 days of SBF immersion in nitric acid surface treated small and larger average particle size foam specimens, respectively. Whereas, the cells of untreated foam specimen were observed to be filled with CaP precipitates and a continuous CaP layer development was found after 14 days of SBF immersion. These results were also confirmed with the grazing incidence XRD and FTIR analysis of SBF immersed specimens. (C) 2010 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The effect of nitric acid surface treatment on CaP deposition of an open-cell Ti6Al4V foam (60% porous and 300-500 m in pore size), prepared by means of the space holder method using 94 and 66 mu m average particle size powders, was investigated in a simulated body fluid (SBF) solution up to 14 days. Although, nitric acid surface treatment did not change the foam flat surface roughness values significantly, it increased surface area difference greatly by introducing nano scale undulations on the surface. The increased surface area difference was found to be more pronounced in smaller particle size foam samples. A continuous relatively thin CaP coating layer formed after 5 and 14 days of SBF immersion in nitric acid surface treated small and larger average particle size foam specimens, respectively. Whereas, the cells of untreated foam specimen were observed to be filled with CaP precipitates and a continuous CaP layer development was found after 14 days of SBF immersion. These results were also confirmed with the grazing incidence XRD and FTIR analysis of SBF immersed specimens. (C) 2010 Elsevier B.V. All rights reserved. |
Turkan, Ugur; Guden, Mustafa The effect of surface treatment on CaP deposition of Ti6Al4V open cell foams in SBF solution Journal Article CERAMICS INTERNATIONAL, 36 (6), pp. 1805-1816, 2010, ISSN: 0272-8842. @article{ISI:000280027800008, title = {The effect of surface treatment on CaP deposition of Ti6Al4V open cell foams in SBF solution}, author = {Ugur Turkan and Mustafa Guden}, doi = {10.1016/j.ceramint.2010.03.030}, issn = {0272-8842}, year = {2010}, date = {2010-08-01}, journal = {CERAMICS INTERNATIONAL}, volume = {36}, number = {6}, pages = {1805-1816}, abstract = {The effects of alkali and nitric acid surface treatment and acid etching on the CaP deposition of an open cell Ti6Al4V foam (60% porous and 300-500 mu m in pore size) developed for biomedical applications were investigated in a simulated body fluid (SBF) solution for 14-day. The surface roughness of the foam specimens ground flat surfaces was measured in nano-metric scale before and after SBF immersion using an atomic force microscope (AFM). A significant increase in the surface roughness of alkali treated foam specimen after SBF immersion indicated a smaller crystal size CaP deposition, which was also confirmed by the AFM micrographs. The microscopic evaluation clearly showed that alkali treatment and nitric acid treatment induced a continuous, uniform CaP deposition on the cell wall surfaces of the foam (interior of cells). While in untreated foam specimen the cells are filled with CaP precipitates and acid etching did not produce a continuous coating layer on particles interior of the cells. The coating layer thickness was similar to 3 mu m in alkali treated foam specimens after 14-day of SBF immersion, while nitric acid treatment induced relatively thinner coating layer, 0.6 mu m. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The effects of alkali and nitric acid surface treatment and acid etching on the CaP deposition of an open cell Ti6Al4V foam (60% porous and 300-500 mu m in pore size) developed for biomedical applications were investigated in a simulated body fluid (SBF) solution for 14-day. The surface roughness of the foam specimens ground flat surfaces was measured in nano-metric scale before and after SBF immersion using an atomic force microscope (AFM). A significant increase in the surface roughness of alkali treated foam specimen after SBF immersion indicated a smaller crystal size CaP deposition, which was also confirmed by the AFM micrographs. The microscopic evaluation clearly showed that alkali treatment and nitric acid treatment induced a continuous, uniform CaP deposition on the cell wall surfaces of the foam (interior of cells). While in untreated foam specimen the cells are filled with CaP precipitates and acid etching did not produce a continuous coating layer on particles interior of the cells. The coating layer thickness was similar to 3 mu m in alkali treated foam specimens after 14-day of SBF immersion, while nitric acid treatment induced relatively thinner coating layer, 0.6 mu m. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved. |
Ozyildiz, E; Guden, M; Uzel, A; Karaboz, I; Akil, O; Bulut, H Antimicrobial Activity of TiO2-coated Orthodontic Ceramic Brackets against Streptococcus mutans and Candida albicans Journal Article BIOTECHNOLOGY AND BIOPROCESS ENGINEERING, 15 (4), pp. 680-685, 2010, ISSN: 1226-8372. @article{ISI:000281514400022, title = {Antimicrobial Activity of TiO2-coated Orthodontic Ceramic Brackets against Streptococcus mutans and Candida albicans}, author = {E Ozyildiz and M Guden and A Uzel and I Karaboz and O Akil and H Bulut}, doi = {10.1007/s12257-009-3005-4}, issn = {1226-8372}, year = {2010}, date = {2010-07-01}, journal = {BIOTECHNOLOGY AND BIOPROCESS ENGINEERING}, volume = {15}, number = {4}, pages = {680-685}, abstract = {Polycrystalline alumina ceramic orthodontic brackets were coated with anatase TiO2 film via a sol-gel dip-coating method. The surface structure morphology and composition of the films were evaluated via scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The antimicrobial activity of the ceramic brackets was assessed against two oral pathogens, S. mutans and C. albicans. The results demonstrated that TiO2-coated brackets exposed to low energy UV-A illumination efficiently reduced the populations of test microorganisms relative to the uncoated brackets. The reduction efficiencies were 98% for S. mutans ATCC 10449 and 93% for C. albicans ATCC 60193.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Polycrystalline alumina ceramic orthodontic brackets were coated with anatase TiO2 film via a sol-gel dip-coating method. The surface structure morphology and composition of the films were evaluated via scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The antimicrobial activity of the ceramic brackets was assessed against two oral pathogens, S. mutans and C. albicans. The results demonstrated that TiO2-coated brackets exposed to low energy UV-A illumination efficiently reduced the populations of test microorganisms relative to the uncoated brackets. The reduction efficiencies were 98% for S. mutans ATCC 10449 and 93% for C. albicans ATCC 60193. |
Toksoy, A K; Guden, M Partial Al foam filling of commercial 1050H14 Al crash boxes: The effect of box column thickness and foam relative density on energy absorption Journal Article THIN-WALLED STRUCTURES, 48 (7), pp. 482-494, 2010, ISSN: 0263-8231. @article{ISI:000278670400002, title = {Partial Al foam filling of commercial 1050H14 Al crash boxes: The effect of box column thickness and foam relative density on energy absorption}, author = {A K Toksoy and M Guden}, doi = {10.1016/j.tws.2010.02.002}, issn = {0263-8231}, year = {2010}, date = {2010-07-01}, journal = {THIN-WALLED STRUCTURES}, volume = {48}, number = {7}, pages = {482-494}, abstract = {The crushing behavior of partially Al closed-cell foam filled commercial 1050H14 Al crash boxes was determined at quasi-static and dynamic deformation velocities. The quasi-static and dynamic crushing of the boxes were simulated using the LS-DYNA. The results showed that partial foam filling tended to change the deformation mode of empty boxes from a non-sequential to a sequential folding mode. In general, the experimental and simulation results showed similar mean load values and deformation modes. The SEA values of empty, partially and fully foam filled boxes were predicted as function of box wall thickness between 1 and 3 mm and foam filler relative density between 0 and 0.2, using the analytical equations developed for the mean crushing loads. The analysis indicated that both fully and partially foam filled boxes were energetically more efficient than empty boxes above a critical foam filler relative density. Partial foam filling, however, decreases the critical foam filler density at increasing box wall thicknesses. (C) 2010 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The crushing behavior of partially Al closed-cell foam filled commercial 1050H14 Al crash boxes was determined at quasi-static and dynamic deformation velocities. The quasi-static and dynamic crushing of the boxes were simulated using the LS-DYNA. The results showed that partial foam filling tended to change the deformation mode of empty boxes from a non-sequential to a sequential folding mode. In general, the experimental and simulation results showed similar mean load values and deformation modes. The SEA values of empty, partially and fully foam filled boxes were predicted as function of box wall thickness between 1 and 3 mm and foam filler relative density between 0 and 0.2, using the analytical equations developed for the mean crushing loads. The analysis indicated that both fully and partially foam filled boxes were energetically more efficient than empty boxes above a critical foam filler relative density. Partial foam filling, however, decreases the critical foam filler density at increasing box wall thicknesses. (C) 2010 Elsevier Ltd. All rights reserved. |
Tasdemirci, A; Ergonenc, C; Guden, M Split Hopkinson pressure bar multiple reloading and modeling of a 316 L stainless steel metallic hollow sphere structure Journal Article INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, 37 (3), pp. 250-259, 2010, ISSN: 0734-743X. @article{ISI:000273106000003, title = {Split Hopkinson pressure bar multiple reloading and modeling of a 316 L stainless steel metallic hollow sphere structure}, author = {A Tasdemirci and C Ergonenc and M Guden}, doi = {10.1016/j.ijimpeng.2009.06.010}, issn = {0734-743X}, year = {2010}, date = {2010-03-01}, journal = {INTERNATIONAL JOURNAL OF IMPACT ENGINEERING}, volume = {37}, number = {3}, pages = {250-259}, abstract = {The high strain rate (600 s(-1)) compression deformation of a 316 L metallic hollow sphere (MHS) structure (density: 500 kg m(-3): average outer hollow sphere diameter: 2 mm and wall thickness: 45 mu m) was determined both numerically and experimentally. The experimental compressive stress-strain behavior at high strain rates until about large strains was obtained with multiple reloading tests using a large-diameter compression type aluminum Split Hopkinson Pressure Bar (SHPB) test apparatus. The multiple reloading of MHS samples in SHPB was analyzed with a 3D finite element model using the commercial explicit finite element code LS-DYNA. The tested MHS samples showed increased crushing stress values, when the strain rate increased from quasi-static (0.8 x 10(-4) s(-1)) to high strain rate (600 s(-1)). Experimentally and numerically deformed sections of MHS samples tested showed very similar crushing characteristics; plastic hinge formation, the indentation of the spheres at the contact regions and sphere wall buckling at intermediate strains. The extent of micro-inertial effects was further predicted with the strain rate insensitive cell wall material model and with the strain rate sensitive behavior of MHS structure similar to that of the cell wall material. Based on the predictions, the strain rate sensitivity of the studied 316 L MHS sample was attributed to the strain rate sensitivity of the cell wall material and the micro-inertia. (C) 2009 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The high strain rate (600 s(-1)) compression deformation of a 316 L metallic hollow sphere (MHS) structure (density: 500 kg m(-3): average outer hollow sphere diameter: 2 mm and wall thickness: 45 mu m) was determined both numerically and experimentally. The experimental compressive stress-strain behavior at high strain rates until about large strains was obtained with multiple reloading tests using a large-diameter compression type aluminum Split Hopkinson Pressure Bar (SHPB) test apparatus. The multiple reloading of MHS samples in SHPB was analyzed with a 3D finite element model using the commercial explicit finite element code LS-DYNA. The tested MHS samples showed increased crushing stress values, when the strain rate increased from quasi-static (0.8 x 10(-4) s(-1)) to high strain rate (600 s(-1)). Experimentally and numerically deformed sections of MHS samples tested showed very similar crushing characteristics; plastic hinge formation, the indentation of the spheres at the contact regions and sphere wall buckling at intermediate strains. The extent of micro-inertial effects was further predicted with the strain rate insensitive cell wall material model and with the strain rate sensitive behavior of MHS structure similar to that of the cell wall material. Based on the predictions, the strain rate sensitivity of the studied 316 L MHS sample was attributed to the strain rate sensitivity of the cell wall material and the micro-inertia. (C) 2009 Elsevier Ltd. All rights reserved. |
2008 |
Tasdemirci, Alper The effect of tube end constraining on the axial crushing behavior of an aluminum tube Journal Article MATERIALS & DESIGN, 29 (10), pp. 1992-2001, 2008, ISSN: 0261-3069. @article{ISI:000258564800014, title = {The effect of tube end constraining on the axial crushing behavior of an aluminum tube}, author = {Alper Tasdemirci}, doi = {10.1016/j.matdes.2008.04.011}, issn = {0261-3069}, year = {2008}, date = {2008-12-01}, journal = {MATERIALS & DESIGN}, volume = {29}, number = {10}, pages = {1992-2001}, abstract = {The effect of various types of end constraining on the deformation and load-displacement behavior of a 3003-H 14 Al tube were experimentally and numerically studied. No effect of single-end constraining of tubes was found. Few conditions of double-end constraining tended to revert the deformation mode to mixed and/or diamond mode of deformation. Double-end constraining of tube ends further resulted in an increase in initial drop-load values, widening the initial overshot region in average load-displacement curves. The agreement between numerical and experimental results showed the capabilities of the used numerical model in order to predict end-condition effects in tubular structures. (C) 2008 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The effect of various types of end constraining on the deformation and load-displacement behavior of a 3003-H 14 Al tube were experimentally and numerically studied. No effect of single-end constraining of tubes was found. Few conditions of double-end constraining tended to revert the deformation mode to mixed and/or diamond mode of deformation. Double-end constraining of tube ends further resulted in an increase in initial drop-load values, widening the initial overshot region in average load-displacement curves. The agreement between numerical and experimental results showed the capabilities of the used numerical model in order to predict end-condition effects in tubular structures. (C) 2008 Elsevier Ltd. All rights reserved. |
Tirtom, Ismail; Guden, Mustafa; Yilidz, Hasan Simulation of the strain rate sensitive flow behavior of SiC-particulate reinforced aluminum metal matrix composites Journal Article COMPUTATIONAL MATERIALS SCIENCE, 42 (4), pp. 570-578, 2008, ISSN: 0927-0256. @article{ISI:000256777300005, title = {Simulation of the strain rate sensitive flow behavior of SiC-particulate reinforced aluminum metal matrix composites}, author = {Ismail Tirtom and Mustafa Guden and Hasan Yilidz}, doi = {10.1016/j.commatsci.2007.09.005}, issn = {0927-0256}, year = {2008}, date = {2008-06-01}, journal = {COMPUTATIONAL MATERIALS SCIENCE}, volume = {42}, number = {4}, pages = {570-578}, abstract = {Strain 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. (C) 2007 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Strain 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. (C) 2007 Elsevier B.V. All rights reserved. |
Tasdemirci, A; Yuksel, S; Karsu, D; Gulturk, E; Hall, I W; Guden, M Diatom frustule-filled epoxy: Experimental and numerical study of the quasi-static and high strain rate compression behavior Journal Article MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 480 (1-2), pp. 373-382, 2008, ISSN: 0921-5093. @article{ISI:000255881300049, title = {Diatom frustule-filled epoxy: Experimental and numerical study of the quasi-static and high strain rate compression behavior}, author = {A Tasdemirci and S Yuksel and D Karsu and E Gulturk and I W Hall and M Guden}, doi = {10.1016/j.msea.2007.07.037}, issn = {0921-5093}, year = {2008}, date = {2008-05-01}, journal = {MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, volume = {480}, number = {1-2}, pages = {373-382}, abstract = {In this study, centric type diatom frustules obtained from a diatomaceous earth filter material were used as filler in an epoxy resin with a weight percentage of 15% in order to assess the possible effects on the compressive behavior at quasi-static and high strain rates. The high strain rate testing of frustule-filled and neat epoxy samples was performed in a split-Hopkinson pressure bar (SHPB) set-up and modeled using the commercial explicit finite element code LS-DYNA 970. Result has shown that 15% frustule filling of epoxy increased both modulus and yield strength values at quasi-static and high strain rates without significantly reducing the failure strain. Microscopic observations revealed two main deformation modes: the debonding of the frustules from the epoxy and crushing/fracture of the frustules. The modeling results have further confirmed the attainment of stress equilibrium in the samples in SHPB testing following the initial elastic region and showed good agreement with the experimental stress-time response and deformation sequence of the samples in high strain rate testing. (C) 2007 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this study, centric type diatom frustules obtained from a diatomaceous earth filter material were used as filler in an epoxy resin with a weight percentage of 15% in order to assess the possible effects on the compressive behavior at quasi-static and high strain rates. The high strain rate testing of frustule-filled and neat epoxy samples was performed in a split-Hopkinson pressure bar (SHPB) set-up and modeled using the commercial explicit finite element code LS-DYNA 970. Result has shown that 15% frustule filling of epoxy increased both modulus and yield strength values at quasi-static and high strain rates without significantly reducing the failure strain. Microscopic observations revealed two main deformation modes: the debonding of the frustules from the epoxy and crushing/fracture of the frustules. The modeling results have further confirmed the attainment of stress equilibrium in the samples in SHPB testing following the initial elastic region and showed good agreement with the experimental stress-time response and deformation sequence of the samples in high strain rate testing. (C) 2007 Elsevier B.V. All rights reserved. |
Guden, Mustafa; Celik, Emrah; Hizal, Alpay; Altindis, Mustafa; Cetiner, Sinan JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS, 85B (2), pp. 547-555, 2008, ISSN: 1552-4973. @article{ISI:000255180900029, title = {Effects of compaction pressure and particle shape on the porosity and compression mechanical properties of sintered Ti6Al4V powder compacts for hard tissue implantation}, author = {Mustafa Guden and Emrah Celik and Alpay Hizal and Mustafa Altindis and Sinan Cetiner}, doi = {10.1002/jbm.b.30978}, issn = {1552-4973}, year = {2008}, date = {2008-05-01}, journal = {JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, volume = {85B}, number = {2}, pages = {547-555}, abstract = {Sintered Ti6Al4V powder compacts potentially to be used in implant applications were prepared using commercially available spherical and angular powders (100-200 mu m) within the porosity range of 34-54%. Cylindrical green powder compacts were cold compacted at various pressures and then sintered at 1200 degrees C for 2 h. The final percent porosity and mean pore sizes were determined as functions of the applied compaction pressure and powder type. The mechanical properties were investigated through compression testing. Results have shown that yield strength of the powder compacts of 40-42% porosity was comparable with that of human cortical bone. As compared with previously investigated Ti powder compacts, Ti6Al4V powder compacts showed higher strength at similar porosity range. Microscopic observations on the failed compact samples revealed that failure occurred primarily by the separation of interparticle bond regions in the planes 45 degrees to the loading axis. (C) 2007 Wiley Periodicals, Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sintered Ti6Al4V powder compacts potentially to be used in implant applications were prepared using commercially available spherical and angular powders (100-200 mu m) within the porosity range of 34-54%. Cylindrical green powder compacts were cold compacted at various pressures and then sintered at 1200 degrees C for 2 h. The final percent porosity and mean pore sizes were determined as functions of the applied compaction pressure and powder type. The mechanical properties were investigated through compression testing. Results have shown that yield strength of the powder compacts of 40-42% porosity was comparable with that of human cortical bone. As compared with previously investigated Ti powder compacts, Ti6Al4V powder compacts showed higher strength at similar porosity range. Microscopic observations on the failed compact samples revealed that failure occurred primarily by the separation of interparticle bond regions in the planes 45 degrees to the loading axis. (C) 2007 Wiley Periodicals, Inc. |
Ince, Umut; Toksoy, Macit; Guden, Mustafa Testing corrosion rates on steel piping in geothermal district heating Journal Article MATERIALS PERFORMANCE, 47 (5), pp. 56-59, 2008, ISSN: 0094-1492. @article{ISI:000255758800018, title = {Testing corrosion rates on steel piping in geothermal district heating}, author = {Umut Ince and Macit Toksoy and Mustafa Guden}, issn = {0094-1492}, year = {2008}, date = {2008-05-01}, journal = {MATERIALS PERFORMANCE}, volume = {47}, number = {5}, pages = {56-59}, abstract = {The St-37 carbon steel piping in a geothermal heating system experienced increasing corrosion leaks. Tests with pipe steel coupons showed that while uniform corrosion rates were low, pitting rates were high. Sulfate-reducing bacteria were the main cause. Changes in fluid velocities and the addition of a bacteriacide were recommended.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The St-37 carbon steel piping in a geothermal heating system experienced increasing corrosion leaks. Tests with pipe steel coupons showed that while uniform corrosion rates were low, pitting rates were high. Sulfate-reducing bacteria were the main cause. Changes in fluid velocities and the addition of a bacteriacide were recommended. |
Aydin, Levent; Artem, Secil Altundag H Axisymmetric crack problem of thick-walled cylinder with loadings on crack surfaces Journal Article ENGINEERING FRACTURE MECHANICS, 75 (6), pp. 1294-1309, 2008, ISSN: 0013-7944. @article{ISI:000253751900002, title = {Axisymmetric crack problem of thick-walled cylinder with loadings on crack surfaces}, author = {Levent Aydin and Secil Altundag H Artem}, doi = {10.1016/j.engfracmech.2007.07.016}, issn = {0013-7944}, year = {2008}, date = {2008-04-01}, journal = {ENGINEERING FRACTURE MECHANICS}, volume = {75}, number = {6}, pages = {1294-1309}, abstract = {This study is concerned with the fracture of an infinite thick-walled cylinder. The inner surface of the cylinder is stress free and the outer is rigidly fixed. The cylinder having a ring-shaped crack located at the symmetry plane is subjected to distributed compressive load on its surfaces. The Hankel and Fourier transform techniques are used for the solution of the field equations. By applying the boundary conditions, the singular integral equation in terms of crack surface displacement derivative is derived. By using an appropriate quadrature formula, the integral equation is reduced to a system of linear algebraic equations. Numerical results are obtained for the stress intensity factors at the edges of the crack, surfaces of which are subjected to uniform, linear and parabolic load distributions. (C) 2007 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study is concerned with the fracture of an infinite thick-walled cylinder. The inner surface of the cylinder is stress free and the outer is rigidly fixed. The cylinder having a ring-shaped crack located at the symmetry plane is subjected to distributed compressive load on its surfaces. The Hankel and Fourier transform techniques are used for the solution of the field equations. By applying the boundary conditions, the singular integral equation in terms of crack surface displacement derivative is derived. By using an appropriate quadrature formula, the integral equation is reduced to a system of linear algebraic equations. Numerical results are obtained for the stress intensity factors at the edges of the crack, surfaces of which are subjected to uniform, linear and parabolic load distributions. (C) 2007 Elsevier Ltd. All rights reserved. |
Tasdemirci, A; Hizal, A; Altindis, M; Hall, I W; Gueden, M The effect of strain rate on the compressive deformation behavior of a sintered Ti6Al4V powder compact Journal Article MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 474 (1-2), pp. 335-341, 2008, ISSN: 0921-5093. @article{ISI:000253030500044, title = {The effect of strain rate on the compressive deformation behavior of a sintered Ti6Al4V powder compact}, author = {A Tasdemirci and A Hizal and M Altindis and I W Hall and M Gueden}, doi = {10.1016/j.msea.2007.05.023}, issn = {0921-5093}, year = {2008}, date = {2008-02-01}, journal = {MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, volume = {474}, number = {1-2}, pages = {335-341}, abstract = {The 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 mu m) 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. (C) 2007 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The 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 mu m) 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. (C) 2007 Elsevier B.V. All rights reserved. |
Aktay, L; Kroeplin, B -H; Toksoy, A K; Guden, M MATERIALS & DESIGN, 29 (5), pp. 952-962, 2008, ISSN: 0261-3069. @article{ISI:000255088000006, title = {Finite element and coupled finite element/smooth particle hydrodynamics modeling of the quasi-static crushing of empty and foam-filled single, bitubular and constraint hexagonal- and square-packed aluminum tubes}, author = {L Aktay and B -H Kroeplin and A K Toksoy and M Guden}, doi = {10.1016/j.matdes.2007.03.019}, issn = {0261-3069}, year = {2008}, date = {2008-01-01}, journal = {MATERIALS & DESIGN}, volume = {29}, number = {5}, pages = {952-962}, abstract = {The quasi-static axial crushing behavior of empty and Al and polystyrene foam-filled Al single, bitubular and multi-tube-packed (hexagonal and square packing) configurations were investigated experimentally and numerically. Tubes were modeled using finite element and coupled finite element/smooth particle hydrodynamics. The numerical specific absorbed energy (SAE) values, deformation patterns, load values and number of folds formed were found to show agreements with those of experiments. Among the tested tube configurations only hexagonal- and square-packed empty tube designs showed increased SAE values over that of single empty tube. Furthermore, foam-filled multi-tube designs both hexagonal- and square-packed designs were found energetically more efficient than Al foam-filled single tubes at similar foam filler densities. The increased SAE values of multi-tubes were attributed to the frictional forces of the multi-tube designs and constraining effect of the die walls accommodating the tubes. (c) 2007 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The quasi-static axial crushing behavior of empty and Al and polystyrene foam-filled Al single, bitubular and multi-tube-packed (hexagonal and square packing) configurations were investigated experimentally and numerically. Tubes were modeled using finite element and coupled finite element/smooth particle hydrodynamics. The numerical specific absorbed energy (SAE) values, deformation patterns, load values and number of folds formed were found to show agreements with those of experiments. Among the tested tube configurations only hexagonal- and square-packed empty tube designs showed increased SAE values over that of single empty tube. Furthermore, foam-filled multi-tube designs both hexagonal- and square-packed designs were found energetically more efficient than Al foam-filled single tubes at similar foam filler densities. The increased SAE values of multi-tubes were attributed to the frictional forces of the multi-tube designs and constraining effect of the die walls accommodating the tubes. (c) 2007 Elsevier Ltd. All rights reserved. |
Aktay, L; Johnson, A F; Toksoy, A K; Kroeplin, B -H; Guden, M MATERIALS & DESIGN, 29 (3), pp. 569-575, 2008, ISSN: 0261-3069. @article{ISI:000253189800001, title = {Modeling the progressive axial crushing of foam-filled aluminum tubes using smooth particle hydrodynamics and coupled finite element model/smooth particle hydrodynamics}, author = {L Aktay and A F Johnson and A K Toksoy and B -H Kroeplin and M Guden}, doi = {10.1016/j.matdes.2007.03.010}, issn = {0261-3069}, year = {2008}, date = {2008-01-01}, journal = {MATERIALS & DESIGN}, volume = {29}, number = {3}, pages = {569-575}, abstract = {As alternatives to the classical finite element model (FEM), a meshless smooth particle hydrodynamics (SPH) method, in which the discrete particles represent a solid domain, and a coupled FEM/SPH modeling technique were investigated for the numerical simulation of the quasi-static axial crushing of polystyrene foam-filled aluminum thin-walled aluminum tubes. The results of numerical simulations, load-deformation histories, fold lengths and specific absorbed energies, were found to show satisfactory correlations with those of experiments and FEM. The results further proved the capabilities of the SPH Method and coupled FEM/SPH modeling technique in predicting the crushing behavior of foam-filled thin-walled tubes. (C) 2007 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } As alternatives to the classical finite element model (FEM), a meshless smooth particle hydrodynamics (SPH) method, in which the discrete particles represent a solid domain, and a coupled FEM/SPH modeling technique were investigated for the numerical simulation of the quasi-static axial crushing of polystyrene foam-filled aluminum thin-walled aluminum tubes. The results of numerical simulations, load-deformation histories, fold lengths and specific absorbed energies, were found to show satisfactory correlations with those of experiments and FEM. The results further proved the capabilities of the SPH Method and coupled FEM/SPH modeling technique in predicting the crushing behavior of foam-filled thin-walled tubes. (C) 2007 Elsevier Ltd. All rights reserved. |
2007 |
Guden, M; Yueksel, S; Tasdemirci, A; Tanoglu, M COMPOSITE STRUCTURES, 81 (4), pp. 480-490, 2007, ISSN: 0263-8223. @article{ISI:000249256200002, title = {Effect of aluminum closed-cell foam filling on the quasi-static axial crush performance of glass fiber reinforced polyester composite and aluminum/composite hybrid tubes}, author = {M Guden and S Yueksel and A Tasdemirci and M Tanoglu}, doi = {10.1016/j.compstruct.2006.09.005}, issn = {0263-8223}, year = {2007}, date = {2007-12-01}, journal = {COMPOSITE STRUCTURES}, volume = {81}, number = {4}, pages = {480-490}, abstract = {The effect of Al closed-cell foam filling on the quasi-static crushing behavior of an E-glass woven fabric polyester composite tube and thin-walled Al/polyester composite hybrid tube was experimentally investigated. For comparison, empty Al, empty composite and empty hybrid tubes were also tested. Empty composite and empty hybrid tubes crushed predominantly in progressive crushing mode, without applying any triggering mechanism. Foam filling was found to be ineffective in increasing the crushing loads of the composite tubes over the sum of the crushing loads of empty composite tube and foam. However, foam filling stabilized the composite progressive crushing mode. In empty hybrid tubes, the deformation mode of the inner Al tube was found to be a more complex form of the diamond mode of deformation of empty Al tube, leading to higher crushing load values than the sum of the crushing load values of empty composite tube and empty metal tube. The foam filling of hybrid tubes however resulted in axial splitting of the outer composite tube due to the resistance imposed by the foam filler to Al tube inward folding and hence it was ineffective in increasing crushing load and SAE values over those of empty hybrid tubes. (C) 2006 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The effect of Al closed-cell foam filling on the quasi-static crushing behavior of an E-glass woven fabric polyester composite tube and thin-walled Al/polyester composite hybrid tube was experimentally investigated. For comparison, empty Al, empty composite and empty hybrid tubes were also tested. Empty composite and empty hybrid tubes crushed predominantly in progressive crushing mode, without applying any triggering mechanism. Foam filling was found to be ineffective in increasing the crushing loads of the composite tubes over the sum of the crushing loads of empty composite tube and foam. However, foam filling stabilized the composite progressive crushing mode. In empty hybrid tubes, the deformation mode of the inner Al tube was found to be a more complex form of the diamond mode of deformation of empty Al tube, leading to higher crushing load values than the sum of the crushing load values of empty composite tube and empty metal tube. The foam filling of hybrid tubes however resulted in axial splitting of the outer composite tube due to the resistance imposed by the foam filler to Al tube inward folding and hence it was ineffective in increasing crushing load and SAE values over those of empty hybrid tubes. (C) 2006 Elsevier Ltd. All rights reserved. |
Tasdemirci, A; Hall, I W The effects of plastic deformation on stress wave propagation in multi-layer materials Journal Article INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, 34 (11), pp. 1797-1813, 2007, ISSN: 0734-743X. @article{ISI:000248761400006, title = {The effects of plastic deformation on stress wave propagation in multi-layer materials}, author = {A Tasdemirci and I W Hall}, doi = {10.1016/j.ijimpeng.2006.10.005}, issn = {0734-743X}, year = {2007}, date = {2007-11-01}, journal = {INTERNATIONAL JOURNAL OF IMPACT ENGINEERING}, volume = {34}, number = {11}, pages = {1797-1813}, abstract = {The behavior of a multi-layer material at high strain rate and the effect of plastic deformation on stress wave propagation were investigated by a combination of experimental and numerical techniques. Plastic deformation effects were studied in multi-layer materials consisting of ceramic, copper and aluminum subjected to large strains under high strain rate loading. First, stress wave propagation behavior for the monolithic metals was studied, and then extended to multilayer combinations of these metals with each other and with a ceramic layer. The axial stress distributions were found to be non-uniform in the elastic deformation range of the specimen. The degree of non-uniformity was much more pronounced in the multi-layer samples consisting of different materials. The presence of a ceramic layer increased the magnitudes of stress gradients at the interfaces. It was also found that a major effect of plastic deformation is a tendency to produce a more homogeneous stress distribution within the components. The implications of these observations for practical systems are discussed. (c) 2006 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The behavior of a multi-layer material at high strain rate and the effect of plastic deformation on stress wave propagation were investigated by a combination of experimental and numerical techniques. Plastic deformation effects were studied in multi-layer materials consisting of ceramic, copper and aluminum subjected to large strains under high strain rate loading. First, stress wave propagation behavior for the monolithic metals was studied, and then extended to multilayer combinations of these metals with each other and with a ceramic layer. The axial stress distributions were found to be non-uniform in the elastic deformation range of the specimen. The degree of non-uniformity was much more pronounced in the multi-layer samples consisting of different materials. The presence of a ceramic layer increased the magnitudes of stress gradients at the interfaces. It was also found that a major effect of plastic deformation is a tendency to produce a more homogeneous stress distribution within the components. The implications of these observations for practical systems are discussed. (c) 2006 Elsevier Ltd. All rights reserved. |
2006 |
Guden, M; Toksoy, A K; Kavi, H Experimental investigation of interaction effects in foam-filled thin-walled aluminum tubes Journal Article JOURNAL OF MATERIALS SCIENCE, 41 (19), pp. 6417-6424, 2006, ISSN: 0022-2461. @article{ISI:000241379600030, title = {Experimental investigation of interaction effects in foam-filled thin-walled aluminum tubes}, author = {M Guden and A K Toksoy and H Kavi}, doi = {10.1007/s10853-006-0722-3}, issn = {0022-2461}, year = {2006}, date = {2006-10-01}, journal = {JOURNAL OF MATERIALS SCIENCE}, volume = {41}, number = {19}, pages = {6417-6424}, abstract = {The interaction coefficients of polystyrene foam filling of thin-walled aluminum cylindrical tubes were investigated experimentally through compression testing of partially foam-filled tubes with and without adhesive. The experimental load-displacement curves and observation of the crushed sections of filled tubes have shown that partial foam filling reduced the fold length and hence increased the average crushing loads of tubes, proving the interaction effect between tube wall and filler. The interaction coefficients for the partial foam filling were further calculated to be in the level and/or higher than that of the foam plateau load of transverse direction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The interaction coefficients of polystyrene foam filling of thin-walled aluminum cylindrical tubes were investigated experimentally through compression testing of partially foam-filled tubes with and without adhesive. The experimental load-displacement curves and observation of the crushed sections of filled tubes have shown that partial foam filling reduced the fold length and hence increased the average crushing loads of tubes, proving the interaction effect between tube wall and filler. The interaction coefficients for the partial foam filling were further calculated to be in the level and/or higher than that of the foam plateau load of transverse direction. |
Aidarova, S B; Musabekov, K B; Ospanova, Z B; Guden, M Foaming binary solution mixtures of low molecular surfactant and polyelectrolyte Journal Article JOURNAL OF MATERIALS SCIENCE, 41 (13), pp. 3979-3986, 2006, ISSN: 0022-2461, (Conference on Syntactic and Composite Foams, Banff, CANADA, AUG 01-05, 2004). @article{ISI:000239282300004, title = {Foaming binary solution mixtures of low molecular surfactant and polyelectrolyte}, author = {S B Aidarova and K B Musabekov and Z B Ospanova and M Guden}, doi = {10.1007/s10853-006-7573-9}, issn = {0022-2461}, year = {2006}, date = {2006-07-01}, journal = {JOURNAL OF MATERIALS SCIENCE}, volume = {41}, number = {13}, pages = {3979-3986}, organization = {ECI}, abstract = {The lifetime of water solution foams of sodium dodecylsulfate (DDS, low molecular weight surfactant) and sodium carboxymethylcellulose (SCMC, polyelectrolyte) and their binary mixtures was experimentally investigated. The effects of ionic strength and acidity on the foam life were also determined. In binary solutions, a synergic effect of DDS and SCMC on the surface tension reduction, most likely resulting from the interaction of the surfactant with polymer, was found. The addition of NaCl into solution or increasing the ionic strength was found to decrease the surface tension and reduce interfacial mobility, hence increased foam lifetime. The relatively low lifetime of binary solution foams in acidic medium was attributed to the reaction between SCMC and acid, which resulted in relatively small reductions in the viscosity and consequently lowered the solution viscosity. (c) 2006 Springer Science + Business Media, Inc.}, note = {Conference on Syntactic and Composite Foams, Banff, CANADA, AUG 01-05, 2004}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lifetime of water solution foams of sodium dodecylsulfate (DDS, low molecular weight surfactant) and sodium carboxymethylcellulose (SCMC, polyelectrolyte) and their binary mixtures was experimentally investigated. The effects of ionic strength and acidity on the foam life were also determined. In binary solutions, a synergic effect of DDS and SCMC on the surface tension reduction, most likely resulting from the interaction of the surfactant with polymer, was found. The addition of NaCl into solution or increasing the ionic strength was found to decrease the surface tension and reduce interfacial mobility, hence increased foam lifetime. The relatively low lifetime of binary solution foams in acidic medium was attributed to the reaction between SCMC and acid, which resulted in relatively small reductions in the viscosity and consequently lowered the solution viscosity. (c) 2006 Springer Science + Business Media, Inc. |
Guden, M; Yuksel, S SiC-particulate aluminum composite foams produced from powder compacts: foaming and compression behavior Journal Article JOURNAL OF MATERIALS SCIENCE, 41 (13), pp. 4075-4084, 2006, ISSN: 0022-2461, (Conference on Syntactic and Composite Foams, Banff, CANADA, AUG 01-05, 2004). @article{ISI:000239282300014, title = {SiC-particulate aluminum composite foams produced from powder compacts: foaming and compression behavior}, author = {M Guden and S Yuksel}, doi = {10.1007/s10853-006-7645-x}, issn = {0022-2461}, year = {2006}, date = {2006-07-01}, journal = {JOURNAL OF MATERIALS SCIENCE}, volume = {41}, number = {13}, pages = {4075-4084}, organization = {ECI}, abstract = {The foaming behavior of SiC-particulate (SiCp) aluminum composite powder compacts containing titanium hydricle blowing agent was investigated by heating to 750 degrees 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. (c) 2006 Springer Science + Business Media, Inc.}, note = {Conference on Syntactic and Composite Foams, Banff, CANADA, AUG 01-05, 2004}, keywords = {}, pubstate = {published}, tppubtype = {article} } The foaming behavior of SiC-particulate (SiCp) aluminum composite powder compacts containing titanium hydricle blowing agent was investigated by heating to 750 degrees 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. (c) 2006 Springer Science + Business Media, Inc. |
Guden, M; Akil, O; Tasdemirci, A; Ciftcioglu, M; Hall, I W Effect of strain rate on the compressive mechanical behavior of a continuous alumina fiber reinforced ZE41A magnesium alloy based composite Journal Article MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 425 (1-2), pp. 145-155, 2006, ISSN: 0921-5093. @article{ISI:000241151500019, title = {Effect of strain rate on the compressive mechanical behavior of a continuous alumina fiber reinforced ZE41A magnesium alloy based composite}, author = {M Guden and O Akil and A Tasdemirci and M Ciftcioglu and I W Hall}, doi = {10.1016/j.msea.2006.03.028}, issn = {0921-5093}, year = {2006}, date = {2006-06-01}, journal = {MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, volume = {425}, number = {1-2}, pages = {145-155}, abstract = {The compressive mechanical response of an FP (TM) continuous fiber (35 vol.%) Mg composite has been determined in the transverse and longitudinal directions at quasi-static and high strain rates. It was found that the composite in the transverse direction exhibited strain rate sensitivity of the flow stress and maximum stress within the studied strain-rate range of 1.3 x 10(-4) to 1550 s(-1). The failure strain in this direction, however, decreased with increasing strain rate. Microscopic observations on the failed samples have shown that the composite failed by shear banding along the diagonal axis, 45 degrees to the loading axis. Twinning was observed in the deformed cross-sections of the samples particularly in and near the shear band region. The strain rate sensitivity of the fracture stress of the composite in transverse direction is attributed to the matrix strain rate sensitivity. In the longitudinal direction, the composite failed by kink formation at quasi-static strain rates, while kinking and splitting were observed at the high strain rates. The maximum stress in the longitudinal direction was, however, found to be strain rate insensitive within the strain rate regime of 1.3 x 10(-4) to 500 s(-1). In this direction, similar to transverse direction, twinning was observed in the highly deformed kink region. Several different reasons are proposed for the strain rate insensitive compressive strength in this direction. (c) 2006 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The compressive mechanical response of an FP (TM) continuous fiber (35 vol.%) Mg composite has been determined in the transverse and longitudinal directions at quasi-static and high strain rates. It was found that the composite in the transverse direction exhibited strain rate sensitivity of the flow stress and maximum stress within the studied strain-rate range of 1.3 x 10(-4) to 1550 s(-1). The failure strain in this direction, however, decreased with increasing strain rate. Microscopic observations on the failed samples have shown that the composite failed by shear banding along the diagonal axis, 45 degrees to the loading axis. Twinning was observed in the deformed cross-sections of the samples particularly in and near the shear band region. The strain rate sensitivity of the fracture stress of the composite in transverse direction is attributed to the matrix strain rate sensitivity. In the longitudinal direction, the composite failed by kink formation at quasi-static strain rates, while kinking and splitting were observed at the high strain rates. The maximum stress in the longitudinal direction was, however, found to be strain rate insensitive within the strain rate regime of 1.3 x 10(-4) to 500 s(-1). In this direction, similar to transverse direction, twinning was observed in the highly deformed kink region. Several different reasons are proposed for the strain rate insensitive compressive strength in this direction. (c) 2006 Elsevier B.V. All rights reserved. |
Sakar-Deliormanli, A; Guden, M Microhardness and fracture toughness of dental materials by indentation method Journal Article JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS, 76B (2), pp. 257-264, 2006, ISSN: 1552-4973. @article{ISI:000234834700003, title = {Microhardness and fracture toughness of dental materials by indentation method}, author = {A Sakar-Deliormanli and M Guden}, doi = {10.1002/jbm.b.30371}, issn = {1552-4973}, year = {2006}, date = {2006-02-01}, journal = {JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, volume = {76B}, number = {2}, pages = {257-264}, abstract = {The main objective of this study was to measure the fracture toughness of the human teeth enamel using the microindentation technique and to compare the results calculated from the equations developed for Palmqvist and radial-median cracks. Vickers microhardness measurements of dental ceramic (alumina) and human teeth were performed using indentation fracture method. The fracture toughness of enamel was calculated using different equations reported in the literature. Vickers microhardness or the sintered alumina specimen (98.8% theoretical density) was measured to be 14.92 GPa under 9.8N indentation load. Three equations based oil the radial-median cracks were found to be applicable for the fracture toughness determination or the enamel. Results show that indentation fracture method is adequate to measure microhardness and fracture toughness of dental materials. However the calculation of fracture toughness depended oil the nature of the cracks and also oil the location of the indentation. Therefore, it is necessary to identify the crack profile and to select the appropriate equation for accurate fracture toughness values. (c) 2005 Wiley Periodicals, Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The main objective of this study was to measure the fracture toughness of the human teeth enamel using the microindentation technique and to compare the results calculated from the equations developed for Palmqvist and radial-median cracks. Vickers microhardness measurements of dental ceramic (alumina) and human teeth were performed using indentation fracture method. The fracture toughness of enamel was calculated using different equations reported in the literature. Vickers microhardness or the sintered alumina specimen (98.8% theoretical density) was measured to be 14.92 GPa under 9.8N indentation load. Three equations based oil the radial-median cracks were found to be applicable for the fracture toughness determination or the enamel. Results show that indentation fracture method is adequate to measure microhardness and fracture toughness of dental materials. However the calculation of fracture toughness depended oil the nature of the cracks and also oil the location of the indentation. Therefore, it is necessary to identify the crack profile and to select the appropriate equation for accurate fracture toughness values. (c) 2005 Wiley Periodicals, Inc. |
Kavi, H; Toksoy, AK; Guden, M Predicting energy absorption in a foam-filled thin-walled aluminum tube based on experimentally determined strengthening coefficient Journal Article MATERIALS & DESIGN, 27 (4), pp. 263-269, 2006, ISSN: 0264-1275. @article{ISI:000233836800001, title = {Predicting energy absorption in a foam-filled thin-walled aluminum tube based on experimentally determined strengthening coefficient}, author = {H Kavi and AK Toksoy and M Guden}, doi = {10.1016/j.matdes.2004.10.024}, issn = {0264-1275}, year = {2006}, date = {2006-01-01}, journal = {MATERIALS & DESIGN}, volume = {27}, number = {4}, pages = {263-269}, abstract = {The energy absorption in a foam-filled thin-walled circular AI tube was investigated based on the experimentally determined strengthening coefficient of filling using AI and polystyrene closed-cell foams with three different densities. Foam filling was found to change the deformation mode of tube from diamond (empty tube) into concertina, regardless the foam type and density used. Although foam filling resulted in higher energy absorption than the sum of the energy absorptions of the tube alone and foam alone, it was not effective in increasing the specific energy than simply thickening the tube wall. It was shown that for efficient foam filling an appropriate foam-tube combination Must be selected by taking into account the magnitude of strengthening coefficient of foam filling and the foam filler plateau load. (c) 2004 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The energy absorption in a foam-filled thin-walled circular AI tube was investigated based on the experimentally determined strengthening coefficient of filling using AI and polystyrene closed-cell foams with three different densities. Foam filling was found to change the deformation mode of tube from diamond (empty tube) into concertina, regardless the foam type and density used. Although foam filling resulted in higher energy absorption than the sum of the energy absorptions of the tube alone and foam alone, it was not effective in increasing the specific energy than simply thickening the tube wall. It was shown that for efficient foam filling an appropriate foam-tube combination Must be selected by taking into account the magnitude of strengthening coefficient of foam filling and the foam filler plateau load. (c) 2004 Elsevier Ltd. All rights reserved. |
Aktay, L; Toksoy, AK; Guden, M Quasi-static axial crushing of extruded polystyrene foam-filled thin-walled aluminum tubes: Experimental and numerical analysis Journal Article MATERIALS & DESIGN, 27 (7), pp. 556-565, 2006, ISSN: 0264-1275. @article{ISI:000236222500003, title = {Quasi-static axial crushing of extruded polystyrene foam-filled thin-walled aluminum tubes: Experimental and numerical analysis}, author = {L Aktay and AK Toksoy and M Guden}, doi = {10.1016/j.matdes.2004.12.019}, issn = {0264-1275}, year = {2006}, date = {2006-01-01}, journal = {MATERIALS & DESIGN}, volume = {27}, number = {7}, pages = {556-565}, abstract = {The 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(TM). 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). (C) 2005 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The 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(TM). 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). (C) 2005 Elsevier Ltd. All rights reserved. |
2005 |
Guden, M; Celik, E; Akar, E; Cetiner, S Compression testing of a sintered Ti6Al4V powder compact for biomedical applications Journal Article MATERIALS CHARACTERIZATION, 54 (4-5), pp. 399-408, 2005, ISSN: 1044-5803. @article{ISI:000229270700014, title = {Compression testing of a sintered Ti6Al4V powder compact for biomedical applications}, author = {M Guden and E Celik and E Akar and S Cetiner}, doi = {10.1016/j.matchar.2005.01.006}, issn = {1044-5803}, year = {2005}, date = {2005-05-01}, journal = {MATERIALS CHARACTERIZATION}, volume = {54}, number = {4-5}, pages = {399-408}, abstract = {in this study, the compression deformation behavior of a Ti6A14V powder compact, prepared by the sintering of cold compacted atomized spherical particles (100-200 mu m) and containing 36-38% porosity, was investigated at quasi-static (1.6 x 10(-3)-1.6 x 10(-1) s(-1)) and high strain rates (300 and 900 s-1) using, respectively, conventional mechanical testing and Split Hopkinson Pressure Bar techniques. Microscopic studies of as-received powder and sintered powder compact showed that sintering at high temperature (1200 degrees C) and subsequent slow rate of cooling in the furnace changed the microstructure of powder from the acicular alpha (alpha) to the Widmanstdtten (alpha+beta) microstructure. In compression testing, at both quasi-static and high strain rates, the compact failed via shear bands formed along the diagonal axis, 45 degrees to the loading direction. Increasing the strain rate was found to increase both the flow stress and compressive strength of the compact but it did not affect the critical strain for shear localization. Microscopic analyses of failed samples and deformed but not failed samples of the compact further showed that fracture occurred in a ductile (dimpled) mode consisting of void initiation and growth in alpha phase and/or at the alpha/beta interface and macrocracking by void coalescence in the interparticle bond region. (c) 2005 Elsevier Inc. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } in this study, the compression deformation behavior of a Ti6A14V powder compact, prepared by the sintering of cold compacted atomized spherical particles (100-200 mu m) and containing 36-38% porosity, was investigated at quasi-static (1.6 x 10(-3)-1.6 x 10(-1) s(-1)) and high strain rates (300 and 900 s-1) using, respectively, conventional mechanical testing and Split Hopkinson Pressure Bar techniques. Microscopic studies of as-received powder and sintered powder compact showed that sintering at high temperature (1200 degrees C) and subsequent slow rate of cooling in the furnace changed the microstructure of powder from the acicular alpha (alpha) to the Widmanstdtten (alpha+beta) microstructure. In compression testing, at both quasi-static and high strain rates, the compact failed via shear bands formed along the diagonal axis, 45 degrees to the loading direction. Increasing the strain rate was found to increase both the flow stress and compressive strength of the compact but it did not affect the critical strain for shear localization. Microscopic analyses of failed samples and deformed but not failed samples of the compact further showed that fracture occurred in a ductile (dimpled) mode consisting of void initiation and growth in alpha phase and/or at the alpha/beta interface and macrocracking by void coalescence in the interparticle bond region. (c) 2005 Elsevier Inc. All rights reserved. |
Toksoy, AK; Guden, M The strengthening effect of polystyrene foam filling in aluminum thin-walled cylindrical tubes Journal Article THIN-WALLED STRUCTURES, 43 (2), pp. 333-350, 2005, ISSN: 0263-8231. @article{ISI:000226331700008, title = {The strengthening effect of polystyrene foam filling in aluminum thin-walled cylindrical tubes}, author = {AK Toksoy and M Guden}, doi = {10.1016/j.tws.2004.07.007}, issn = {0263-8231}, year = {2005}, date = {2005-02-01}, journal = {THIN-WALLED STRUCTURES}, volume = {43}, number = {2}, pages = {333-350}, abstract = {The 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. (C) 2004 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The 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. (C) 2004 Elsevier Ltd. All rights reserved. |
2004 |
Guden, M; Yildirim, U; Hall, IW Effect of strain rate on the compression behavior of a woven glass fiber/SC-15 composite Journal Article POLYMER TESTING, 23 (6), pp. 719-725, 2004, ISSN: 0142-9418. @article{ISI:000223093900014, title = {Effect of strain rate on the compression behavior of a woven glass fiber/SC-15 composite}, author = {M Guden and U Yildirim and IW Hall}, doi = {10.1016/j.polymertesting.2004.01.004}, issn = {0142-9418}, year = {2004}, date = {2004-09-01}, journal = {POLYMER TESTING}, volume = {23}, number = {6}, pages = {719-725}, abstract = {Strain rate dependent compression behavior of a plain-weave S-2 glass fabric SC-15 epoxy (rubber toughened resin) composite plate, currently studied as the backing plate for composite armor applications, was determined in the through-thickness direction (normal to the fiber plane) in the strain rate regime of 1 x 10(-4) to 1.1 x 103 s(-1). In the studied strain rate regime, the modulus and failure strength of the composite were found to be rate sensitive and increased with increasing strain rate. Microscopic observations showed that the composite failed by ductile failure, involving matrix cracks and, later, cracking through and between the fiber layers. Crack deflections at rubber particle/matrix interface and particle pull-out were observed in the failed samples, contributing to the toughness of the composite. (C) 2004 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Strain rate dependent compression behavior of a plain-weave S-2 glass fabric SC-15 epoxy (rubber toughened resin) composite plate, currently studied as the backing plate for composite armor applications, was determined in the through-thickness direction (normal to the fiber plane) in the strain rate regime of 1 x 10(-4) to 1.1 x 103 s(-1). In the studied strain rate regime, the modulus and failure strength of the composite were found to be rate sensitive and increased with increasing strain rate. Microscopic observations showed that the composite failed by ductile failure, involving matrix cracks and, later, cracking through and between the fiber layers. Crack deflections at rubber particle/matrix interface and particle pull-out were observed in the failed samples, contributing to the toughness of the composite. (C) 2004 Elsevier Ltd. All rights reserved. |
Karamis, MB; Nair, F; Tasdemirci, A Analyses of metallurgical behavior of Al-SiCp composites after ballistic impacts Journal Article COMPOSITE STRUCTURES, 64 (2), pp. 219-226, 2004, ISSN: 0263-8223. @article{ISI:000223157500009, title = {Analyses of metallurgical behavior of Al-SiCp composites after ballistic impacts}, author = {MB Karamis and F Nair and A Tasdemirci}, doi = {10.1016/j.compstruct.2003.08.005}, issn = {0263-8223}, year = {2004}, date = {2004-05-01}, journal = {COMPOSITE STRUCTURES}, volume = {64}, number = {2}, pages = {219-226}, abstract = {The dynamic failure of SiC particle reinforced aluminum alloy composite; AA5083 is studied under ballistic impact loading. Tests were done with two different projectile types, AP (Army Piercing) 7.62 and 9 mm, and the hole surfaces created by the projectiles were investigated using both optical and scanning electron microscopy. Examination of the hole surface of the composite after dynamic failure showed microscopically ductile failure in the matrix following brittle cracking of the particles. The dynamic failure process involved both matrix and particle cracking. The high velocity of the projectile led to the melting of some surface layers because of the excess heat resulting from high velocity friction. Because of high friction, some melted regions had a porous structure due to shrinkage during rapid solidification caused by the high-speed projectile at the hole surface. The type of projectile strongly influenced the damage formation and the deformation type was also affected by the backing condition. (C) 2003 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The dynamic failure of SiC particle reinforced aluminum alloy composite; AA5083 is studied under ballistic impact loading. Tests were done with two different projectile types, AP (Army Piercing) 7.62 and 9 mm, and the hole surfaces created by the projectiles were investigated using both optical and scanning electron microscopy. Examination of the hole surface of the composite after dynamic failure showed microscopically ductile failure in the matrix following brittle cracking of the particles. The dynamic failure process involved both matrix and particle cracking. The high velocity of the projectile led to the melting of some surface layers because of the excess heat resulting from high velocity friction. Because of high friction, some melted regions had a porous structure due to shrinkage during rapid solidification caused by the high-speed projectile at the hole surface. The type of projectile strongly influenced the damage formation and the deformation type was also affected by the backing condition. (C) 2003 Elsevier Ltd. All rights reserved. |
Tasdemirci, A; Hall, IW; Gama, BA; Guiden, M Stress wave propagation effects in two- and three-layered composite materials Journal Article JOURNAL OF COMPOSITE MATERIALS, 38 (12), pp. 995-1009, 2004, ISSN: 0021-9983. @article{ISI:000222365200002, title = {Stress wave propagation effects in two- and three-layered composite materials}, author = {A Tasdemirci and IW Hall and BA Gama and M Guiden}, doi = {10.1177/0021998304040564}, issn = {0021-9983}, year = {2004}, date = {2004-01-01}, journal = {JOURNAL OF COMPOSITE MATERIALS}, volume = {38}, number = {12}, pages = {995-1009}, abstract = {Multilayer materials consisting of ceramic and glass/epoxy composites have been subjected to high strain rate compression testing using the Split Hopkinson Pressure Bar. The samples were extensively strain gaged so that dynamic data were generated directly from the samples during testing. Output data from the experiments were compared with numerical simulations of the same experiments and good agreement was noted. It was found that the stress distribution within samples was quite inhomogeneous and that stresses were highest in the region of the bar-sample interface. The presence of a rubber interlayer between the ceramic and glass/epoxy decreased the stress in both components but dramatically increased the degree of stress inhomogeneity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Multilayer materials consisting of ceramic and glass/epoxy composites have been subjected to high strain rate compression testing using the Split Hopkinson Pressure Bar. The samples were extensively strain gaged so that dynamic data were generated directly from the samples during testing. Output data from the experiments were compared with numerical simulations of the same experiments and good agreement was noted. It was found that the stress distribution within samples was quite inhomogeneous and that stresses were highest in the region of the bar-sample interface. The presence of a rubber interlayer between the ceramic and glass/epoxy decreased the stress in both components but dramatically increased the degree of stress inhomogeneity. |
2003 |
Akil, O; Yildirim, U; Guden, M; Hall, IW Effect of strain rate on the compression behaviour of a woven fabric S2-glass fiber reinforced vinyl ester composite Journal Article POLYMER TESTING, 22 (8), pp. 883-887, 2003, ISSN: 0142-9418. @article{ISI:000186300400006, title = {Effect of strain rate on the compression behaviour of a woven fabric S2-glass fiber reinforced vinyl ester composite}, author = {O Akil and U Yildirim and M Guden and IW Hall}, doi = {10.1016/S0142-9418(03)00026-6}, issn = {0142-9418}, year = {2003}, date = {2003-12-01}, journal = {POLYMER TESTING}, volume = {22}, number = {8}, pages = {883-887}, abstract = {Quasi-static (similar to10(-3)s(-1)) and high strain rate ( > 500 s(-1)) compression behavior of ail S2-glass woven fabric/vinyl ester composite plate was determined in the in-plane and through-thickness directions. In both directions, modulus and failure strength increased with increasing strain rate. A higher strain rate sensitive modulus was found in the through-thickness direction while a higher strain rate sensitive failure strength was found in the in-plane direction. In the inplane direction, the failure mode was observed to change from splitting followed by ``kink banding'' (localized fiber buckling) to predominantly splitting at increasing strain rates, while it remained the same in the through-thickness direction. (C) 2003 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Quasi-static (similar to10(-3)s(-1)) and high strain rate ( > 500 s(-1)) compression behavior of ail S2-glass woven fabric/vinyl ester composite plate was determined in the in-plane and through-thickness directions. In both directions, modulus and failure strength increased with increasing strain rate. A higher strain rate sensitive modulus was found in the through-thickness direction while a higher strain rate sensitive failure strength was found in the in-plane direction. In the inplane direction, the failure mode was observed to change from splitting followed by ``kink banding'' (localized fiber buckling) to predominantly splitting at increasing strain rates, while it remained the same in the through-thickness direction. (C) 2003 Elsevier Ltd. All rights reserved. |
Elbir, S; Yilmaz, S; Toksoy, AK; Guden, M SiC-particulate aluminum composite foams produced by powder compacts: Foaming and compression behavior Journal Article JOURNAL OF MATERIALS SCIENCE, 38 (23), pp. 4745-4755, 2003, ISSN: 0022-2461. @article{ISI:000186420800012, title = {SiC-particulate aluminum composite foams produced by powder compacts: Foaming and compression behavior}, author = {S Elbir and S Yilmaz and AK Toksoy and M Guden}, doi = {10.1023/A:1027427102837}, issn = {0022-2461}, year = {2003}, date = {2003-12-01}, journal = {JOURNAL OF MATERIALS SCIENCE}, volume = {38}, number = {23}, pages = {4745-4755}, abstract = {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 (750degreesC) 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. (C) 2003 Kluwer Academic Publishers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } 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 (750degreesC) 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. (C) 2003 Kluwer Academic Publishers. |
Hall, IW; Guden, M Split Hopkinson Pressure Bar compression testing of an aluminum alloy: Effect of lubricant type Journal Article JOURNAL OF MATERIALS SCIENCE LETTERS, 22 (21), pp. 1533-1535, 2003, ISSN: 0261-8028. @article{ISI:000185963100017, title = {Split Hopkinson Pressure Bar compression testing of an aluminum alloy: Effect of lubricant type}, author = {IW Hall and M Guden}, doi = {10.1023/A:1026167517837}, issn = {0261-8028}, year = {2003}, date = {2003-11-01}, journal = {JOURNAL OF MATERIALS SCIENCE LETTERS}, volume = {22}, number = {21}, pages = {1533-1535}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Lopatnikov, SL; Gama, BA; Haque, MJ; Krauthauser, C; Gillespie, JW; Guden, M; Hall, IW Dynamics of metal foam deformation during Taylor cylinder-Hopkinson bar impact experiment Journal Article COMPOSITE STRUCTURES, 61 (1-2), pp. 61-71, 2003, ISSN: 0263-8223, (14th US National Congress of Theoretical and Applied Mechanics, BLACKSBURG, VIRGINIA, JUN 23-28, 2002). @article{ISI:000183147900007, title = {Dynamics of metal foam deformation during Taylor cylinder-Hopkinson bar impact experiment}, author = {SL Lopatnikov and BA Gama and MJ Haque and C Krauthauser and JW Gillespie and M Guden and IW Hall}, doi = {10.1016/S0263-8223(03)00039-4}, issn = {0263-8223}, year = {2003}, date = {2003-07-01}, journal = {COMPOSITE STRUCTURES}, volume = {61}, number = {1-2}, pages = {61-71}, abstract = {Analytical solutions for dynamic deformation of foam materials during the Taylor cylinder-Hopkinson bar impact experiment were obtained. It was shown that shock wave of foam collapse appears during the fast impact. The results of this experiment can be used in estimating the average material properties of the foam under dynamic loading conditions. Results show that the undeformed and change in length of foam specimens are in good agreement between theory and experiment, as well as numerical analysis. (C) 2003 Published by Elsevier Science Ltd.}, note = {14th US National Congress of Theoretical and Applied Mechanics, BLACKSBURG, VIRGINIA, JUN 23-28, 2002}, keywords = {}, pubstate = {published}, tppubtype = {article} } Analytical solutions for dynamic deformation of foam materials during the Taylor cylinder-Hopkinson bar impact experiment were obtained. It was shown that shock wave of foam collapse appears during the fast impact. The results of this experiment can be used in estimating the average material properties of the foam under dynamic loading conditions. Results show that the undeformed and change in length of foam specimens are in good agreement between theory and experiment, as well as numerical analysis. (C) 2003 Published by Elsevier Science Ltd. |
2002 |
Artem, HSA; Gecit, MR An elastic hollow cylinder under axial tension containing a crack and two rigid inclusions of ring shape Journal Article COMPUTERS & STRUCTURES, 80 (27-30), pp. 2277-2287, 2002, ISSN: 0045-7949, (5th International Conference on Computational Structures Technology/2nd International Conference on Engineering Computational Technology, LEUVEN, BELGIUM, SEP 06-08, 2000). @article{ISI:000179864300028, title = {An elastic hollow cylinder under axial tension containing a crack and two rigid inclusions of ring shape}, author = {HSA Artem and MR Gecit}, doi = {10.1016/S0045-7949(02)00236-5}, issn = {0045-7949}, year = {2002}, date = {2002-11-01}, journal = {COMPUTERS & STRUCTURES}, volume = {80}, number = {27-30}, pages = {2277-2287}, abstract = {This paper is concerned with the fracture of an axisymmetric hollow cylindrical bar containing rigid inclusions. The cylinder is under the action of uniformly distributed axial tension applied at infinity. The bar contains a ring-shaped crack at the symmetry plane whose surfaces are free of tractions and two ring-shaped rigid inclusions with negligible thickness symmetrically located on both sides of the crack. It is assumed that the material of the cylinder is linearly elastic and isotropic. The mixed boundary conditions of the problem lead the analysis to a system of three singular integral equations for crack surface displacement derivative and normal and shearing stress jumps on rigid inclusions. These integral equations are solved numerically and the stress intensity factors are calculated. (C) 2002 Civil-Comp Ltd. and Elsevier Science Ltd. All rights reserved.}, note = {5th International Conference on Computational Structures Technology/2nd International Conference on Engineering Computational Technology, LEUVEN, BELGIUM, SEP 06-08, 2000}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper is concerned with the fracture of an axisymmetric hollow cylindrical bar containing rigid inclusions. The cylinder is under the action of uniformly distributed axial tension applied at infinity. The bar contains a ring-shaped crack at the symmetry plane whose surfaces are free of tractions and two ring-shaped rigid inclusions with negligible thickness symmetrically located on both sides of the crack. It is assumed that the material of the cylinder is linearly elastic and isotropic. The mixed boundary conditions of the problem lead the analysis to a system of three singular integral equations for crack surface displacement derivative and normal and shearing stress jumps on rigid inclusions. These integral equations are solved numerically and the stress intensity factors are calculated. (C) 2002 Civil-Comp Ltd. and Elsevier Science Ltd. All rights reserved. |
Greene, SA; Hall, IW; Guden, M Improving the energy absorption of closed cell aluminum foams Journal Article JOURNAL OF MATERIALS SCIENCE LETTERS, 21 (20), pp. 1591-1593, 2002, ISSN: 0261-8028. @article{ISI:000178181700011, title = {Improving the energy absorption of closed cell aluminum foams}, author = {SA Greene and IW Hall and M Guden}, doi = {10.1023/A:1020361331280}, issn = {0261-8028}, year = {2002}, date = {2002-10-01}, journal = {JOURNAL OF MATERIALS SCIENCE LETTERS}, volume = {21}, number = {20}, pages = {1591-1593}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Hall, IW; Guden, M; Claar, TD Transverse and longitudinal crushing of aluminum-foam filled tubes Journal Article SCRIPTA MATERIALIA, 46 (7), pp. 513-518, 2002, ISSN: 1359-6462. @article{ISI:000175844200006, title = {Transverse and longitudinal crushing of aluminum-foam filled tubes}, author = {IW Hall and M Guden and TD Claar}, doi = {10.1016/S1359-6462(02)00024-6}, issn = {1359-6462}, year = {2002}, date = {2002-04-01}, journal = {SCRIPTA MATERIALIA}, volume = {46}, number = {7}, pages = {513-518}, abstract = {Al-foam filled and empty tubes of aluminum, brass and titanium were compression tested laterally. The specific energy absorption in filled tubes increased greatly in terms of percentages, and was greatest in aluminum tubes. In transversely tested tubes the foam deformed laterally showing a capability of spreading the deformation. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Al-foam filled and empty tubes of aluminum, brass and titanium were compression tested laterally. The specific energy absorption in filled tubes increased greatly in terms of percentages, and was greatest in aluminum tubes. In transversely tested tubes the foam deformed laterally showing a capability of spreading the deformation. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. |
2001 |
Hall, IW; Guden, M High strain rate testing of a unidirectionally reinforced graphite epoxy composite Journal Article JOURNAL OF MATERIALS SCIENCE LETTERS, 20 (10), pp. 897-899, 2001, ISSN: 0261-8028. @article{ISI:000169504000005, title = {High strain rate testing of a unidirectionally reinforced graphite epoxy composite}, author = {IW Hall and M Guden}, doi = {10.1023/A:1010968514339}, issn = {0261-8028}, year = {2001}, date = {2001-05-01}, journal = {JOURNAL OF MATERIALS SCIENCE LETTERS}, volume = {20}, number = {10}, pages = {897-899}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Hall, IW; Ebil, O; Guden, M; Yu, CJ Quasi-static and dynamic crushing of empty and foam-filled tubes Journal Article JOURNAL OF MATERIALS SCIENCE, 36 (24), pp. 5853-5860, 2001, ISSN: 0022-2461. @article{ISI:000172368200017, title = {Quasi-static and dynamic crushing of empty and foam-filled tubes}, author = {IW Hall and O Ebil and M Guden and CJ Yu}, doi = {10.1023/A:1012916408297}, issn = {0022-2461}, year = {2001}, date = {2001-01-01}, journal = {JOURNAL OF MATERIALS SCIENCE}, volume = {36}, number = {24}, pages = {5853-5860}, abstract = {Metallic foam-filled tubes and their empty counterparts have been tested at quasi-static and dynamic strain rates in order to determine their energy absorption capabilities. Data from the Split-Hopkinson Pressure Bar have been used to generate force vs. displacement curves that are somewhat analogous to pseudo-engineering stress-strain curves. Force balance calculations have also been made. These results indicate that, on an equal weight basis, foam-filled tubes offer greater energy absorption capability than empty tubes at quasi-static strain rates. However, the benefit of foam filling does not appear to be extended to strain rates of the order of 200-500 s(-1). Force balance calculations are shown to have potential as a method for monitoring the crushing of metallic foams at high strain rate. (C) 2001 Kluwer Academic Publishers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metallic foam-filled tubes and their empty counterparts have been tested at quasi-static and dynamic strain rates in order to determine their energy absorption capabilities. Data from the Split-Hopkinson Pressure Bar have been used to generate force vs. displacement curves that are somewhat analogous to pseudo-engineering stress-strain curves. Force balance calculations have also been made. These results indicate that, on an equal weight basis, foam-filled tubes offer greater energy absorption capability than empty tubes at quasi-static strain rates. However, the benefit of foam filling does not appear to be extended to strain rates of the order of 200-500 s(-1). Force balance calculations are shown to have potential as a method for monitoring the crushing of metallic foams at high strain rate. (C) 2001 Kluwer Academic Publishers. |
2000 |
Hall, IW; Guden, M; Yu, CJ Crushing of aluminum closed cell foams: Density and strain rate effects Journal Article SCRIPTA MATERIALIA, 43 (6), pp. 515-521, 2000, ISSN: 1359-6462. @article{ISI:000089373000007, title = {Crushing of aluminum closed cell foams: Density and strain rate effects}, author = {IW Hall and M Guden and CJ Yu}, doi = {10.1016/S1359-6462(00)00460-7}, issn = {1359-6462}, year = {2000}, date = {2000-08-01}, journal = {SCRIPTA MATERIALIA}, volume = {43}, number = {6}, pages = {515-521}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Guden, M; Hall, IW High strain rate deformation behavior of a continuous fiber reinforced aluminum metal matrix composite Journal Article COMPUTERS & STRUCTURES, 76 (1-3), pp. 139-144, 2000, ISSN: 0045-7949, (Conference of the NATO-Advanced-Study-Institue on Mechanics of Composite Materials and Structures, TROIA, PORTUGAL, JUL 12-24, 1998). @article{ISI:000086637000014, title = {High strain rate deformation behavior of a continuous fiber reinforced aluminum metal matrix composite}, author = {M Guden and IW Hall}, doi = {10.1016/S0045-7949(99)00158-3}, issn = {0045-7949}, year = {2000}, date = {2000-06-01}, journal = {COMPUTERS & STRUCTURES}, volume = {76}, number = {1-3}, pages = {139-144}, organization = {NATO, Inst Adv Study; IDMEC; Inst Mech Engn; Inst Super Tecn; Tech Univ Lisbon}, abstract = {An aluminum metal matrix composite reinforced with continuous unidirectional alpha-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. (C) 2000 Elsevier Science Ltd. All rights reserved.}, note = {Conference of the NATO-Advanced-Study-Institue on Mechanics of Composite Materials and Structures, TROIA, PORTUGAL, JUL 12-24, 1998}, keywords = {}, pubstate = {published}, tppubtype = {article} } An aluminum metal matrix composite reinforced with continuous unidirectional alpha-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. (C) 2000 Elsevier Science Ltd. All rights reserved. |
1998 |
Guden, M; Hall, IW High strain rate properties of an SiCW/2124-T6 aluminum composite at elevated temperatures Journal Article SCRIPTA MATERIALIA, 39 (3), pp. 261-267, 1998, ISSN: 1359-6462. @article{ISI:000075059600001, title = {High strain rate properties of an SiCW/2124-T6 aluminum composite at elevated temperatures}, author = {M Guden and IW Hall}, doi = {10.1016/S1359-6462(98)00169-9}, issn = {1359-6462}, year = {1998}, date = {1998-07-01}, journal = {SCRIPTA MATERIALIA}, volume = {39}, number = {3}, pages = {261-267}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Guden, M; Hall, IW Quasi-static and dynamic compression behaviour of an FP (TM) alumina-reinforced aluminium metal matrix composite Journal Article JOURNAL OF MATERIALS SCIENCE, 33 (13), pp. 3285-3291, 1998, ISSN: 0022-2461. @article{ISI:000077590800008, title = {Quasi-static and dynamic compression behaviour of an FP (TM) alumina-reinforced aluminium metal matrix composite}, author = {M Guden and IW Hall}, doi = {10.1023/A:1013272910939}, issn = {0022-2461}, year = {1998}, date = {1998-07-01}, journal = {JOURNAL OF MATERIALS SCIENCE}, volume = {33}, number = {13}, pages = {3285-3291}, abstract = {An aluminium metal matrix composite reinforced with continuous unidirectional alpha-alumina fibres has been compression tested at quasi-static and dynamic strain rates. In the transverse direction, the composite showed increasing flow stress (at 5% strain) and maximum stress within the studied strain rates, 10(-3)-3 x 10(3) s(-1). In the longitudinal direction, the maximum stress of the composite increased similarly with increasing strain rates within the range 10(-5)-7 x 10(2) s(-1). If is shown that, if brooming of the sam pie ends can be suppressed, the failure stress of the composite in longitudinal compression increases significantly. Metallographic observations reveal the typical modes of damage initiation in the composite. (C) 1998 Kluwer Academic Publishers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } An aluminium metal matrix composite reinforced with continuous unidirectional alpha-alumina fibres has been compression tested at quasi-static and dynamic strain rates. In the transverse direction, the composite showed increasing flow stress (at 5% strain) and maximum stress within the studied strain rates, 10(-3)-3 x 10(3) s(-1). In the longitudinal direction, the maximum stress of the composite increased similarly with increasing strain rates within the range 10(-5)-7 x 10(2) s(-1). If is shown that, if brooming of the sam pie ends can be suppressed, the failure stress of the composite in longitudinal compression increases significantly. Metallographic observations reveal the typical modes of damage initiation in the composite. (C) 1998 Kluwer Academic Publishers. |
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| Eksen Kaçıklığının Yapısal Titreşime Etkisi | Prof. Dr. Bülent Yardımoğlu | 2004 | İYTE-BAP |
| Hidrojen Depolanması Ve Dağıtımı Amaçlı Yüksek Basınca Dayanıklı Hafif Kompozit Tank Malzemelerinin Ve Sistemlerinin Tasarlanması, Optimizasyonu Ve Prototip İmalatlarının Gerçekleştirilmesi | Doç. Dr. H. Seçil ARTEM | 2016 | TÜBİTAK |
| Beton Için Yeni Bir Statik Ve Dinamik Mekanik Karakterizasyon Metodolojisi Geliştirilmesi | Prof. Dr. Alper Taşdemirci | 2015 | TÜBİTAK |
| Patlamaya Dayanıklı Yarı Küresel Tekrarlı Çekirdek Malzemesi Ihtiva Eden Sandviç Yapıların Geliştirilmesi Ve Optimizasyonu | Prof. Dr. Alper Taşdemirci | 2014 | TÜBİTAK |
