Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Homogenization of 3d Laminated Micro-Structures Including Bending Effects
    (Pergamon-elsevier Science Ltd, 2024) Oezdemir, Izzet
    In this paper, a homogenization method which captures intrinsic size effect associated with fiber diameter is revisited and adapted for three-dimensional laminated micro -structures. Based on a unit-cell composed of matrix and reinforcement layers, enhanced deformation gradients varying through the thickness, are introduced with the aid of an additional kinematic variable reflecting the difference between the homogenized and constituent level deformation gradients. In the current work, as opposed to the original formulation, higher order terms are preserved for both phases and therefore bending stiffness of the matrix phase can be taken into account as well. The formulation is implemented within the commercial finite element solver Abaqus through user element (UEL) subroutine considering a finite strain hyperelastic response for the reinforcement layers and a von Mises type hyper-elastoplastic one for the matrix phase. Explicitly discretized unit-cells with varying reinforcement phase fraction, layer inclination angle and layer thicknesses are used as references to assess the predictive capabilities of the homogenized model and the significance of bending stiffness of the phases. Similarly, explicitly discretized model of a beam type structure with a crossed lamellar micro -structure is used to evaluate the performance of the homogenized model under more general, non-periodic boundary conditions. The findings of both cases support the effectiveness of the homogenized model.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 10
    Experimental 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, Mustafa
    The 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.