WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 28Citation - Scopus: 28Crushing Behavior and Energy Absorption Performance of a Bio-Inspired Metallic Structure: Experimental and Numerical Study(Elsevier Ltd., 2018) Taşdemirci, Alper; Akbulut, Emine Fulya; Güzel, Erkan; Tüzgel, Fırat; Yücesoy, Atacan; Şahin, Selim; Güden, MustafaA thin-walled structure inspired from a biologic creature known as balanus was investigated experimentally and numerically under quasi-static and dynamic loads for load-carrying and energy absorption properties. The structure was composed of an inner conical core with a hemispherical cap and an outer shell in frusto-conical shape and formed by deep drawing. The applied deep drawing process was modelled using nonlinear finite element code LS-DYNA to determine the residual stress/strain and the non-linear thickness distribution after the forming process. It was also shown that the load carried by the balanus structure was greater than the arithmetic sum of the load carried by the inner core and by the outer shell separately. Although the mean force increase due to interaction effect at quasi-static strain rate was approximately 5%, while it increased to roughly 26% at dynamic strain rates in drop weight experiments. The numerical models also showed that the outer shell absorbed more energy than the inner core while the difference between the energy absorbing performance of the core and shell decreased with increasing deformation rate. The effect of strain rate and inertia on the increase in crush load increased with increasing impact velocity, while the strain rate effect had greater influence than the inertia on the crush load. The increased load carrying capacity of the balanus at quasi-static and dynamic strain rates was ascribed to the interaction between the core and shell and the confinement effect of the outer shell particularly at dynamic strain rate.Article Citation - WoS: 12Citation - Scopus: 15Effect of Heat Treatment on the Blast Loading Response of Combined Geometry Shell Core Sandwich Structures(Elsevier Ltd., 2016) Taşdemirci, Alper; Kara, Ali; Turan, Kıvanç; Şahin, Selim; Güden, MustafaThe effect of heat treatment on the dynamic crushing and energy absorption behavior of combined geometry shell cores (hemisphere and cylinder) of sandwich structures were investigated both experimentally and numerically. The applied heat treatment on the combined geometry shell cores relieved the stress caused by deep drawing, diminishing the peak transmitted forces. The verified numerical models of the as-received and heat-treated combined geometry shells were used to model blast loading of various sandwich configurations and the additional sandwich configurations of reversing the cylindrical side of the cores to the impacted side. Both the applied heat-treatment and the reversing process decreased the magnitude of the force transmitted to the protected structure. The applied heat treatment increased the arrival time of blast force wave to the protected structure, while the reversing resulted in opposite.Article Citation - WoS: 29Citation - Scopus: 32The Optimisation of the Energy Absorption of Partially Al Foam-Filled Commercial 1050h14 and 6061t4 Al Crash Boxes(Taylor and Francis Ltd., 2011) Toksoy, Ahmet Kaan; Güden, MustafaPartially 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.Article Citation - WoS: 153Citation - Scopus: 163Predicting Energy Absorption in a Foam-Filled Thin-Walled Aluminum Tube Based on Experimentally Determined Strengthening Coefficient(Elsevier Ltd., 2006) Kavi, Halit; Toksoy, Ahmet Kaan; Güden, MustafaThe energy absorption in a foam-filled thin-walled circular Al tube was investigated based on the experimentally determined strengthening coefficient of filling using Al 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.Article Citation - WoS: 40Citation - Scopus: 52Partial Al Foam Filling of Commercial 1050h14 Al Crash Boxes: the Effect of Box Column Thickness and Foam Relative Density on Energy Absorption(Elsevier Ltd., 2010) Toksoy, Ahmet Kaan; Güden, MustafaThe 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.Article Citation - WoS: 14Citation - Scopus: 14Modeling the Progressive Axial Crushing of Foam-Filled Aluminum Tubes Using Smooth Particle Hydrodynamics and Coupled Finite Element Model/Smooth Particle Hydrodynamics(Elsevier Ltd., 2008) Aktay, Levent; Johnson, Alastair F.; Toksoy, Ahmet Kaan; Kröplin, Bernd Helmut; Güden, MustafaAs 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.Article Citation - WoS: 53Citation - Scopus: 56Finite 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(Elsevier Ltd., 2008) Aktay, Levent; Kröplin, Bernd Helmut; Toksoy, Ahmet Kaan; Güden, MustafaThe 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.Article Citation - WoS: 44Citation - Scopus: 47Effect of Aluminum Closed-Cell Foam Filling on the Quasi-Static Axial Crush Performance of Glass Fiber Reinforced Polyester Composite and Aluminum/Composite Hybrid Tubes(Elsevier Ltd., 2007) Güden, Mustafa; Yüksel, Sinan; Taşdemirci, Alper; Tanoğlu, MetinThe 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.