Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 5Citation - Scopus: 6The Varying Densification Strain in a Multi-Layer Aluminum Corrugate Structure: Direct Impact Testing and Layer-Wise Numerical Modelling(Elsevier Ltd., 2017) Odacı, İsmet Kutlay; Güden, Mustafa; Kılıçaslan, Cenk; Taşdemirci, AlperAn aluminum (1050 H14) multi-layer corrugated structure composed of brazed 16 trapezoidal zig-zig fin layers was direct impact tested above the critical velocities for shock formation using a modified Split Hopkinson Pressure Bar. The experimentally measured stress-time histories of the cylindrical test samples in the direct impact tests were verified with the simulations implemented in the explicit finite element code of LS–DYNA. The quasi-static experimental and simulation deformation of the corrugated samples proceeded with the discrete, non-contiguous bands of crushed fin layers, while the dynamic crushing started from the proximal impact end and proceeded with a sequential and in-planar manner, showing shock type deformation characteristic. The experimental and numerical crushing stresses and the numerically determined densification strains of the fin layers increased with increasing impact velocity above the critical velocities. When the numerically determined densification strain at a specific velocity above the critical velocities was incorporated, the rigid-perfectly-plastic-locking idealized model resulted in peak stresses similar to the experimental and simulation mean crushing stresses. However, the model underestimated the experimental and simulation peak stresses below 200 m s−1. It was proposed, while the micro inertial effects were responsible for the increase of the crushing stresses at and below subcritical velocities, the shock deformation became dominant above the critical velocities.Article Citation - WoS: 71Citation - Scopus: 81The Impact Responses and the Finite Element Modeling of Layered Trapezoidal Corrugated Aluminum Core and Aluminum Sheet Interlayer Sandwich Structures(Elsevier Ltd., 2013) Kılıçaslan, Cenk; Güden, Mustafa; Odacı, İsmet Kutlay; Taşdemirci, AlperThe impact responses of brazed and adhesively bonded layered 1050 H14 trapezoidal corrugated aluminum core and aluminum sheet interlayer sandwich panels with 3003 and 1050 H14 aluminum alloy face sheets were investigated in a drop weight tower using spherical, flat and conical end striker tips. The full geometrical models of the tests were implemented using the LS-DYNA. 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 impacted using a conical striker tip were penetrated/perforated and showed comparably smaller deformation forces and energy absorptions, especially in 0°/90° layer orientation. The simulation and experimental force values were shown to reasonably agree with each other at the large extent of deformation and revealed the progressive fin folding of corrugated core layers and bending of interlayer sheets as the main deformation mechanisms. The experimentally and numerically determined impact velocity sensitivity of the tested panels was attributed to the micro inertial effects which increased the critical buckling loads of fin layers at increasingly high loading rates.Article Citation - WoS: 14Citation - Scopus: 18Projectile Impact Testing of Glass Fiber-Reinforced Composite and Layered Corrugated Aluminium and Aluminium Foam Core Sandwich Panels: a Comparative Study(Taylor and Francis Ltd., 2012) Odacı, İsmet Kutlay; Kılıçaslan, Cenk; Taşdemirci, Alper; Güden, MustafaE-glass/polyester composite and layered corrugated aluminium and aluminium foam core sandwich panels were projectile impact tested between 127 m/s and 190 m/s using a hardened steel sphere projectile. The corrugated aluminium cores, constructed from aluminium fin layers and aluminium interlayers and face sheets, exhibited relatively lower-plateau stresses and higher stress oscillations in the plateau region than aluminium foam cores. The applied brazing process resulted in reductions in the plateau stresses of the corrugated aluminium cores. The sandwich panels with 2- and 3-mm-thick composite face sheets and the epoxy-bonded corrugated aluminium sheet cores were perforated, while the sandwich panels with 5-mm-thick composite face sheets were penetrated in the projectile impact tests. On the other hand, the sandwich panels with aluminium foam cores were only penetrated. A simple comparison between the ballistic limits of the sandwich panels as a function of total weight revealed significant increases in the ballistic limits of the cores with the inclusion of composite face sheets. The determined higher impact resistance of the foam core sandwich panels was attributed to the relatively higher strength of the foam cores investigated and the ability to distribute the incident impulse to a relatively large area of the backing composite plate.Article Citation - WoS: 11Citation - Scopus: 10Experimental Testing and Full and Homogenized Numerical Models of the Low Velocity and Dynamic Deformation of the Trapezoidal Aluminium Corrugated Core Sandwich(John Wiley and Sons Inc., 2014) Kılıçaslan, Cenk; Odacı, İsmet Kutlay; Taşdemirci, Alper; Güden, MustafaThe simulations of the low velocity and dynamic deformation of a multi-layer 1050-H14 Al trapezoidal zig-zag corrugated core sandwich were investigated using the homogenized models (solid models) of a single core layer (without face sheets). In the first part of the study, the LS-DYNA MAT-26 material model parameters of a single core layer were developed through experimental and numerical compression tests on the single core layer. In the second part, the fidelities of the developed numerical models were checked by the split-Hopkinson pressure bar direct impact, low velocity compression and indentation and projectile impact tests. The results indicated that the element size had a significant effect on the initial peak and post-peak stresses of the homogenized models of the direct impact testing of the single-layer corrugated sandwich. This was attributed to the lack of the inertial effects in the homogenized models, which resulted in reduced initial peak stresses as compared with the full model and experiment. However, the homogenized models based on the experimental stress–strain curve of the single core layer predicted the low velocity compression and indentation and projectile impact tests of the multi-layer corrugated sandwich with an acceptable accuracy and reduced the computational time of the models significantly.