Browsing by Author "Toksoy, Ahmet Kaan"

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Investigation of hybridization effect on ballistic performance of multi-layered fiber reinforced composite structures
(Sage Publications Ltd, 2022) Ustun, Hikmet Sinan; Toksoy, Ahmet Kaan; Tanoglu, Metin; Tanoğlu, Metin
The aim of this study is enhancing the ballistic performance of multi-layered fiber reinforced composite structures by hybridization approach against fragment simulating projectile (FSP). For manufacturing of homogeneous and hybrid composite structures, 170 g/m(2) twill weave aramid and 280 g/m(2) plain weave E-Glass fibers were used with epoxy resin systems and two different thickness values for each composite panel were fabricated and tested to obtain a relationship between areal density and V-50 parameters. Tensile, 3-point bending, and short beam strength tests of composite panels were performed, and ballistic performance of composite structures were measured by V-50 test method with 1.1 g FSP threat. Ballistic performance of hybrid composite structures was compared with high-performance composite ballistic panel test results reported in literature. As a result, it was found that E-Glass fabric layers together with aramid fabrics increased the energy absorbing capability of hybrid composite panels and ballistic performance was enhanced to be similar or higher than ballistic fiber reinforced composites. Hence, hybridization was found to be an effective way to enhance ballistic performance of fiber reinforced composite structures.
Optimization of the axial crushing behavior of closed-cell aluminum foam filled welded 1050 al square-cross section crashboxes
(Izmir Institute of Technology, 2009) Toksoy, Ahmet Kaan; Güden, Mustafa
The crushing behavior of partially Al closed-cell foam (Alulight AlSi10) filled 1050H14 Al crash boxes was investigated at quasi-static and dynamic deformation velocities. The quasi-static crushing of empty and filled boxes was further simulated using LS-DYNA. Finally, the crushing of partially foam filled 1050H14 crash boxes was optimized using the response surface methodology. The used optimization methodology was also applied to the boxes made of a stronger Al alloy, 6061T4 Al, and filled with a higher strength Al foam, Hydro Al closed cell foam, in order to clarify the effect of box material and foam filler strength on the crushing behavior of the filled boxes. Within the investigated tube thickness and foam relative density range, the energy absorption of 1050H14 boxes was optimized at 3 mm wall thickness and 0.1114 (Alulight) and 0.0508 (Hydro foam) foam filler relative density. The increase in specific energy absorption of 1050H14 crash box was 5.6% with Alulight and 21.9% for Hydro foam filling. 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 decreased the critical foam filler density at increasing box wall thicknesses.
Quasi-static axial compression behavior of empty and polystyrene foam filled aluminum tubes
(Izmir Institute of Technology, 2003) Toksoy, Ahmet Kaan; Güden, Mustafa
The strengthening effect of foam filling and the effect of foam filling on the crushing properties of the light weight foam filled circular tubes were investigated through the polystyrene foam filled thin-walled Al tubes of 16 and 25 mm in diameter. The empty tubes crushed progressively in asymmetric (diamond) mode. The foam filling however turned the deformation mode into progressive axisymmetric (concertina) mode in 25 mm Al tube, while the deformation mode in foam filled 16 mm Al tube remained to be the same with that of the empty tube. The strengthening coefficients of foam-filling defined as the ratio between the increase in the average crushing load of the filled tube with respect to empty tube and plateau load (load corresponding to the plateau stress of the foam) were found to be 1.8 and 3.2 for the concertina and diamond mode of deformation, respectively. The higher value of strengthening in diamond mode of deformation was attributed to the filler deformation beyond the densification region. This was also confirmed by the microscopic observation of the partially crushed sections of the filled tubes. The interaction effect between tube and filler was assessed by the compression testing of the partially foam filled tubes. The effects of filler density, deformation rate (in the range between 0.001-0.04 s-1) and the use of adhesive between the tube wall and filler on the average crushing load, stroke efficiency and specific absorbed energy of the tubes were determined. The specific absorbed energy of the filled tube was compared with that of the empty tubes of wall thickening on the equal mass basis. Finally, two modes of deformation modes were proposed for the crushing behavior of the foam filled thin-walled Al tubes.