Taşdemirci, Alper
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Tasdemirci, A
Tasdemirci, A.
Tasdemirci, Alper
Taşdemirci, A.
Taşdemirci, A
Tasdemirci, A.
Tasdemirci, Alper
Taşdemirci, A.
Taşdemirci, A
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alpertasdemirci@iyte.edu.tr
Main Affiliation
03.10. Department of Mechanical Engineering
Status
Current Staff
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1NO POVERTY
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
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7AFFORDABLE AND CLEAN ENERGY
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
22
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10REDUCED INEQUALITIES
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Documents
61
Citations
1496
h-index
24
Documents
58
Citations
1291
Scholarly Output
90
Articles
50
Views / Downloads
96357/45132
Supervised MSc Theses
22
Supervised PhD Theses
8
WoS Citation Count
1116
Scopus Citation Count
1300
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0
Projects
13
WoS Citations per Publication
12.40
Scopus Citations per Publication
14.44
Open Access Source
70
Supervised Theses
30
| Journal | Count |
|---|---|
| Thin-Walled Structures | 8 |
| International Journal of Impact Engineering | 7 |
| Materials and Design | 5 |
| Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing | 4 |
| Strain | 4 |
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Now showing 1 - 10 of 90
Article Citation - WoS: 60Citation - Scopus: 70Foam Glass Processing Using a Polishing Glass Powder Residue(Elsevier Ltd., 2013) Attila, Yiğit; Güden, Mustafa; Taşdemirci, AlperThe foaming behavior of a powder residue/waste of a soda-lime window glass polishing facility was investigated at the temperatures between 700 and 950 °C. The results showed that the foaming of the glass powder started at a characteristic temperature between 670 and 680 °C. The maximum volume expansions of the glass powder and the density of the foams varied between 600% and 750% and 0.206 and 0.378 g cm−3, respectively. The expansion of the studied glass powder residue resulted from the decomposition of the organic compounds on the surfaces of the glass powder particles, derived from an oil-based coolant used in the polishing. The collapse stress of the foams ranged between ∼1 and 4 MPa and the thermal conductivity between 0.048 and 0.079 W K−1 m−1. Both the collapse stress and thermal conductivity increased with increasing the foam density. The foams showed the characteristics of the compression deformation of the open cell brittle foams, which was attributed to the relatively thick cell edges.Master Thesis The Development of a New Testing Methodology in Dynamic Mechanical Chracterization of Concrete(Izmir Institute of Technology, 2018) Seven, Semih Berk; Güden, Mustafa; Taşdemirci, Alper; Taşdemirci, Alper; Güden, MustafaConcrete is one of the most used material types in the world. Due to its structural complexity and insufficient testing techniques, the dynamic mechanical behavior of concrete has not yet been revealed sufficiently. This thesis aims to develop reliable and accurate mechanical characterization methodology for concrete using the combination of experimental and numerical methods together. The dynamic mechanical characterization of concrete at quasi-static and high strain rates was performed implementing unique techniques for both experimental and numerical studies. In quasi-static testing, universal compression test machine was used with strain gage mounted specimen for better strain measurements. In high strain rate tests, two modifications were implemented on the conventional Split Hopkinson Pressure Bar (SHPB) test apparatus. The first modification is the usage of pulse shaper to obtain nearly constant strain rate and dynamic stress equilibrium in the specimen. Second, piezo-electric quartz crystal force transducers were implemented on the specimen-bar interfaces to increase accuracy and sensitivity of the force measurement on the front and back forces of the specimen. Experimental results were validated constituting numerical study using finite element tool LS-DYNA. Concrete was modeled using Holmquist-Johnson-Cook (MAT_111) material model. HJC material model parameters were determined using experimental results coupling with the numerical analysis and the mechanical behavior of concrete was constituted. It was concluded that using pulse shaper and quartz crystals pretty useful when testing concrete and other brittle materials at high strain rates. Modification of new specimen geometries on numerical analysis showed better understandings of the effect of geometry on the dynamic stress equilibrium.Conference Object Projectile Impact Testing Aluminum Corrugated Core Composite Sandwiches Using Aluminum Corrugated Projectiles: Experimental and Numerical Investigation(Trans Tech Publications, 2017) Odacı, İsmet Kutlay; Kılıçaslan, Cenk; Taşdemirci, Alper; Mamalis, Athanasios G.; Güden, MustafaE-glass/polyester composite plates and 1050 H14 aluminum trapezoidal corrugated core composite sandwich plates were projectile impact tested using 1050 H14 aluminum trapezoidal fin corrugated projectiles with and without face sheets. The projectile impact tests were simulated in LS-DYNA. The MAT_162 material model parameters of the composite were determined and then optimized by the quasi-static and high strain rate tests. Non-centered projectile impact test models were validated by the experimental and numerical back face displacements of the impacted plates. Then, the centered projectile impact test models were developed and the resultant plate displacements were compared with those of the TNT mass equal Conwep simulations. The projectiles with face sheets induced similar displacement with the Conwep blast simulation, while the projectiles without face sheets underestimated the Conwep displacements, which was attributed to more uniform pressure distribution with the use of the face sheets on the test plates. © 2018 Trans Tech Publications, Switzerland.Doctoral Thesis Experimental and Numerical Investigation of the Quasi-Static and High Strain Rate Crushing Behavior of Single and Multi-Layer Zig-Zag 1050 H14 Al Trapezoidal Corrugated Core Sandwich Structures(Izmir Institute of Technology, 2014) Kılıçaslan, Cenk; Güden, Mustafa; Taşdemirci, Alper; Güden, Mustafa; Taşdemirci, AlperThe quasi-static and dynamic crushing behavior of single, double and multi-layer zig-zag 1050 H14 Al trapezoidal corrugated core sandwich structures in 0°/0° and 0°/90° core orientations and with and without interlayer sheets were investigated both experimentally and numerically at varying impact velocities. The numerical simulations were conducted using the finite element code of LS-DYNA. The effect of fin wall imperfection was assessed through the fin wall bending and bulging. The numerical homogenization of the single layer corrugated structure was performed using MAT26 honeycomb material model. The buckling stress of single- and double-layer corrugated sandwich structures increased when the strain rate increased. The increased buckling stresses were ascribed to the micro inertial effects. The initial buckling stress at quasi-static and high strain rate was numerically shown to be imperfection sensitive. Increasing the number of core layers decreased the buckling stress and increased the densification strain. The panels tested with spherical and flat striker tips were not penetrated and experienced slightly higher deformation forces and energy absorptions in 0°/90° corrugated layer orientation than in 0°/0° orientation. However, the panels tested using a conical striker tip were penetrated/perforated and showed comparably smaller deformation forces and energy absorptions, especially in 0°/90° layer orientation. The homogenized models predicted the low velocity compression /indentation and projectile impact tests of the multi-layer corrugated sandwich with an acceptable accuracy with reduced computational time.Article The Johnson and Cook Damage and Flow Stress Model Parameters of a Rolled Stainless Steel 304 Alloy(Elsevier, 2026) Akdogan, Ibrahim Berk; Davut, Kemal; Gueden, Mustafa; Erten, Hacer Irem; Tasdemirci, Alper; Maleki, Farshid Khosravi; Gok, Mustafa SabriPrevious studies on stainless steel 304 alloy (SS 304) have mostly focused on the stress-strain behavior as function of the volume fraction of deformation induced martensite and the applied strain and strain rate. Although equally important, the failure/fracture of this alloy has not been thoroughly investigated so far. In the present study, the Johnson and Cook (JC) damage model parameters of a rolled-SS 304 alloy, valid at a high strain rate (2900 s-1), were experimentally determined and numerically validated along with the JC flow stress parameters. The tensile failure strain of the alloy decreased as the strain rate increased from 10-3 to 10-1 s-1 and to 2900 s-1. Experimentally lower flow stresses at 2900 s-1 than at 1x10-3 s-1 were also found at the strains above 0.2, which was attributed to the adiabatic heating that declined the extend of the martensitic transformation at increasing strains. The determined damage and flow stress model parameters were further calibrated with the results of the numerical models of the quasi-static and high strain rate tension tests. Microscopic analyses and the hardness measurements on the untested and tested specimens confirmed the martensitic transformation and the highest hardness values were found in the specimens tested at 1x10-3 s-1. The martensite volume fraction as function strain rate until about necking strain (homogeneous deformation) was calculated and also microscopically determined using the electron back-scatter diffraction (EBSD) for the specimens tested at different strain rates. The results indicated the highest martensite volume fraction in the specimens tested at 10-3 s-1 (0.55-0.6) and the lowest in the specimens tested at the high strain rate (0.27-0.30). An agreement between the calculated and the EBSD determined martensite volume fractions was shown for the studied alloy.Master Thesis The Investigation of Static and Dynamic Compressive Deformation Behavior of a Paper Based Sandwich Material(01. Izmir Institute of Technology, 2022) İmrağ, Berkay Türkcan; Taşdemirci, Alper; Taşdemirci, AlperIn this study, dynamic and quasi-static compression behavior of paper-based honeycomb sandwich structures were investigated. It is known that the mechanical properties of paper-based honeycomb structures change with changing strain rate values. For this reason, dynamic and quasi-static loading conditions should be considered separately when investigating the compressive behavior of the structure. In the material characterization studies, a series of tests were conducted to examine mechanical properties of the paper layer material and sandwich structure. Using data from mechanical tests, numerical models were established in the finite element tool LS-DYNA. Outputs of numerical models were validated with mechanical test outputs. After the validation study, the effects that influence the dynamic compressive behavior of the paper-based honeycomb sandwich structure and their contribution percentages were investigated using the opportunities provided by the FE tool. The results showed a 150.48 % difference between the dynamic and quasi-static compressive behavior of the structure. The numerical results obtained from explicit and implicit solvers also showed good correlation with the experimental results. In addition, the micro-mechanical modeling approach in numerical models made it possible to investigate the effects such as strain rate sensitivity of the paper layer material, entrapped air inside the core cells, and micro-inertia individually. The contribution percentages of the effects were calculated by comparing the numerical and experimental results.Article Citation - WoS: 9Citation - Scopus: 12The Effect of Tube End Constraining on the Axial Crushing Behavior of an Aluminum Tube(Elsevier Ltd., 2008) Taşdemirci, AlperThe effect of various types of end constraining on the deformation and load-displacement behavior of a 3003-H14 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.Article Citation - WoS: 3Citation - Scopus: 3Quasi-Static and Dynamic Brazilian Testing and Failure Analysis of a Deer Antler in the Transverse To the Osteon Growth Direction(Elsevier, 2023) Orhan, Mehmet; Sarıkaya, Mustafa Kemal; Taşdemirci, Alper; Tuncer, Can; Güden, MustafaThe transverse tensile strength of a naturally fallen red deer antler (Cervus Elaphus) was determined through indirect Brazilian tests using dry disc-shape specimens at quasi-static and high strain rates. Dynamic Brazilian tests were performed in a compression Split-Hopkinson Pressure Bar. Quasi-static tensile and indirect Brazilian tests were also performed along the osteon growth direction for comparison. The quasi-static transverse tensile strength ranged 31.5–44.5 MPa. The strength increased to 83 MPa on the average in the dynamic Brazilian tests, proving a rate sensitive transverse strength. The quasi-static tensile strength in the osteon growth direction was however found comparably higher, 192 MPa. A Weibull analysis indicated a higher tensile ductility in the osteon growth direction than in the transverse to the osteon growth direction. The microscopic analysis of the quasi-static Brazilian test specimens (tensile strain along the osteon growth direction) revealed a micro-cracking mechanism operating by the crack deflection/twisting at the lacunae in the concentric lamellae region and at the interface between concentric lamellae and interstitial lamellae. On the other side, the specimens in the transverse direction fractured in a more brittle manner by the separation/delamination of the concentric lamellae and pulling of the interstitial lamellae. The detected increase in the transverse strength in the high strain rate tests was further ascribed to the pull and fracture of the visco-plastic collagen fibers in the interstitial lamellae. This was also confirmed microscopically; the dynamically tested specimens exhibited flatter fracture surfaces. © 2023 Elsevier LtdArticle Citation - WoS: 1Citation - Scopus: 1Investigation of Penetration Behavior of Combined Geometry Shells at Quasi-Static and Intermediate Strain Rates: an Experimental and Numerical Study(Elsevier, 2023) Turan, Ali Kıvanç; Taşdemirci, Alper; Kara, Ali; Şahin, Selim; Güden, MustafaIn this study, the penetration/perforation behavior of a core material with previously determined static and dynamic crushing characteristics was investigated both experimentally and numerically. Penetration/perforation problems occur due to shrapnel effect when sandwich structures containing energy-absorbing core materials by crushing are exposed to blast loads. The penetration behavior of combined geometry shells consisting of a hemispherical cap and a cylindrical segment was investigated experimentally using blunt, conical and hemispherical penetrator tips. The quasi-static penetration tests were performed in a universal test machine, and the intermediate strain rate penetration tests were performed in a drop weight test device. The numerical models of penetration tests were implemented in LS-DYNA at the test strain rates as well as at the higher strain rates. Results showed that different penetrator geometries induced damage forms of symmetrical tearing, petaling, plugging and inversely formed hemispherical domed cone. The increase in the thickness of core geometry resulted in a decent increase in force–displacement curves, as average of force levels increased around 140%, 200% and 220% for blunt, conical and hemispherical tip penetrators, respectively. Numerical results indicated very good correlation with experimental work and enabled to investigate effect of strain rate and micro-inertia over numerical models at elevated penetrator velocities. Penetration behavior was found to be affected from micro-inertia effects up to a threshold displacement of 4 mm for thicker and 5 mm for thinner core units and strain rate effects were found to be dominant beyond that point.Article Citation - WoS: 14Citation - Scopus: 18Dynamic Crushing and Energy Absorption of Sandwich Structures With Combined Geometry Shell Cores(Elsevier Ltd., 2015) Taşdemirci, Alper; Kara, Ali; Turan, Kıvanç; Şahin, SelimDynamic crushing and energy absorption characteristics of sandwich structures with combined geometry shell cores were investigated experimentally and numerically. The effect of strain rate on the crushing behavior was presented by the crushing tests at quasi-static, intermediate and high strain rate regimes. It was shown that absorbed energy increased with increasing impact velocity. The effect of confinement on crushing behavior was shown by conducting confined experiments at quasi-static and dynamic rates. Higher buckling loads at lower deformation were observed in confined quasi-static crushing due to additional lateral support and friction provided by confinement wall. By using fictitious numerical models with strain rate insensitive material models, the effect of inertia and strain rate on crushing were shown. It was observed that, increase in impact velocity caused increase in inertial effects and strain rate effects were nearly independent from the impact velocity. The effects of multilayering were also investigated numerically.