Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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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; Güden, Mustafa; Taşdemirci, Alper; Taşdemirci, Alper; Odacı, İsmet Kutlay; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAn 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: 70Citation - Scopus: 81Experimental and Numerical Studies on the Quasi-Static and Dynamic Crushing Responses of Multi-Layer Trapezoidal Aluminum Corrugated Sandwiches(Elsevier Ltd., 2014) Kılıçaslan, Cenk; Güden, Mustafa; Taşdemirci, Alper; Taşdemirci, Alper; Güden, Mustafa; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe axial crushing responses of bonded and brazed multi-layer 1050 H14 trapezoid alaluminum corru- gated core (fin) sandwich structures, with and without aluminum interlayer sheets in 0°/0° and 0°/90° core orientations, were both experimentally and numerically investigated at quasi-static and dynamic strain rates. Multi-layering the core layers decreased the buckling stress and increased the densification strain. The experimental and simulation compression stress–strain curves showed reasonable agree-ments with each other. Two main crushing modes were observed experimentally and numerically: the progressive fin folding and the shearing interlayer aluminum sheets. Both, the simulation and experimental buckling and post-buckling stresses increased when the interlayer sheets were constraint laterally. The multi-layer samples without interlayer sheets in 0°/90° core orientation exhibited higher buckling stresses than the samples in 0°/0° core orientation. The increased buckling stress of 0°/0° oriented core samples without interlayer sheets at high strain rate was attributed to the micro-inertial effects which led to increased bending forces at higher impact velocities.