Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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Institution Author: search.filters.institutionAuthor.Odacı, İsmet KutlaySubject: search.filters.subject.Aluminum

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 5
    Citation - Scopus: 6
    The 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, Alper
    An 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: 71
    Citation - Scopus: 81
    The 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, Alper
    The 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: 27
    Citation - Scopus: 30
    Single- and Double-Layer Aluminum Corrugated Core Sandwiches Under Quasi-Static and Dynamic Loadings
    (SAGE Publications Inc., 2016) Kılıçaslan, Cenk; Odacı, İsmet Kutlay; Güden, Mustafa
    The crushing of single- and double-layer zig-zag trapezoidal corrugated core sandwiches was investigated experimentally and numerically at quasi-static and dynamic rates. The buckling stress of sandwiches increased when the rate increased from quasi-static to dynamic. The increased buckling stresses were ascribed to the micro-inertial effects, which altered the buckling mode of the core from three plastic hinges to higher number of plastic hinge formations. The initial buckling stress was numerically shown to be imperfection sensitive when the imperfection size was comparable with the buckling length. The numerical buckling stresses of zig-zag and straight corrugated cores were similar, while higher inertial effects were found in triangular corrugated core.