Browsing by Author "Demiral, Murat"

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Citation Count: Mahmoud, A.K...et al. "A Study of the Structural and Mechanical Characterization of Hybrid Nanocomposite Material", Materials Science Forum, Vol. 909, pp. 111-115, (2017).
A Study of the Structural and Mechanical Characterization of Hybrid Nanocomposite Material
(Trans Tech Publications LTD, 2017) Mahmoud, A. K.; Al-Nassar, S. I.; Demiral, Murat; Kadhim, H. M.
This work is devoted on the synthesized new hybrid nanocomposite materials by using mechanical stirring method through a combination of different types of material; epoxy based matrix and nanofiller (TiO2 nanoparticles) as a reinforcement material. In additional this paper studies the effect of TiO2 nanoparticles with percentage 2-8 wt% added to epoxy based matrix on the mechanical properties (tensile properties and hardness property). The results showed that the tensile strength of nanocomposite material increased gradually by increasing the weight percentage of TiO2 nanoparticles from 2 wt % to 8 wt % TiO2, while the best tensile strength was at 8 wt % TiO2. The maximum value of tensile strength was 270% higher than the neat epoxy matrix. The hardness increase gradually with increasing percentage of TiO2 nanoparticles from 2wt% TiO2 up to 8wt% TiO2, the maximum value of hardness was at 8wt % TiO2, so the hardness of nanocomposite is around 86% higher than the neat epoxy matrix
Citation Count: Demiral, M...et al. (2017). Enhanced gradient crystal-plasticity study of size effects in a beta-titanium alloy. Modelling and Simulation in Materials Science and Engineering, 25(3). http://dx.doi.org/10.1088/1361-651X/aa5ce3
Enhanced gradient crystal-plasticity study of size effects in a beta-titanium alloy
(IOP Publishing Ltd, 2017) Demiral, Murat; Nowag, Kai; Roy, Anish; Ghisleni, Rudy; Michler, Johann; Silberschmidt, Vadim V.
A calibrated model of enhanced strain-gradient crystal plasticity is proposed, which is shown to characterize adequate deformation behaviour of bcc single crystals of a beta-Ti alloy (Ti-15-3-3-3). In this model, in addition to strain gradients evolving in the course of deformation, incipient strain gradients, related to a component's surface-to-volume ratio, is accounted for. Predictive capabilities of the model in characterizing a size effect in an initial yield and a work-hardening rate in small-scale components is demonstrated. The characteristic length-scale, i.e. the component's dimensions below which the size effect is observed, was found to depend on densities of polar and statistical dislocations and interaction between them.
Citation Count: Oliaei, Samad Nadimi Bavil; Demiral, Murat (2017). "Finite element modeling of mechanical micromachining", Advanced Machining Processes: Innovative Modeling Techniques, pp. 245-280.
Finite element modeling of mechanical micromachining
(2017) Oliaei, Samad Nadimi Bavil; Demiral, Murat
The knowledge about all these phenomena is necessary to fabricate microparts, satisfying required dimensional and geometrical tolerances and surface quality requirements. Therefore, developing predictive techniques to improve the quality of microparts has emerged as an important research area. Several approaches have been used to predict outputs of microcutting operations including analytical modeling, numerical techniques, molecular dynamics simulation, and experimental studies. As experimental studies are costly and time consuming and as they are only valid for the conditions and range of machining parameters used in the experiments, numerical methods are used as an alternative method to predict machining process outputs. © 2018 by Taylor & Francis Group, LLC.
Citation Count: Liu, Qian...et al. " Modelling and simulations of nanoindentation in single crystals", Applied Nanoindentation İn Advanced Materials, pp.561-577, (2017).
Modelling and simulations of nanoindentation in single crystals
(John Wiley and Sons LTD., 2017) Liu, Qiang; Demiral, Murat; Roy, Anish; Silberschmidt, Vadim V.
Citation Count: Kadıoğlu, Ferhat...et al (2018). "Performance of adhesively-bonded joints of laminated composite materials under different loading modes", AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2018.
Performance of adhesively-bonded joints of laminated composite materials under different loading modes
(2018) Kadıoğlu, Ferhat; Demiral, Murat; Avil, Esma; Ercan, M. Emin; Aydoğan, Tuncay; 205907
The aim of this work is to investigate quasi-static performance of adhesively-bonded joints with adherends manufactured from a laminated composite material under tensile and bending loading modes. For this purpose, a film adhesive, AF163-2K, produced by 3M, and a glass fiber reinforced polymer matrix composite, Hexply 913/33%/UD280, produced by Hexcel were used. In the current work, numerical analysis of the joints was carried out using ABAQUS/Standard finite element program, and also a series of experimental studies were conducted. While the thickness of the adherends and the adhesive layer were kept constant, 2 mm and 0.200 mm, respectively, the composite adherends with 10 layers for different fiber orientations - 10°, 20°, 45° and 55° (symmetric and balanced) – and for different overlap lengths, 15 mm, 25 mm and 40 mm, were considered. Our results showed that failure mechanisms in the joints was different from each other for different loading modes. Numerically obtained stress distributions in the joints and composites give insight into the experimentally obtained results.
Citation Count: Asim, U., Siddiq, M.A., Demiral, M. (2017). Void growth in high strength aluminium alloy single crystals: a CPFEM based study. Modelling and Simulation in Materials Science and Engineering, 25(3). http://dx.doi.org/ 10.1088/1361-651X/aa5bcc
Void growth in high strength aluminium alloy single crystals: a CPFEM based study
(IOP Publishing Ltd, 2017) Asim, Umair; Siddiq, M. Amir; Demiral, Murat
High strength aluminium alloys that are produced through forming and joining processes are widely used in aerospace components. The ductile failure in these metals occurs due to the evolution and accumulation of microscopic defects, such as microvoids and shear bands. The present work investigates the underlying physical mechanisms during ductile failure by performing a rigorous, fully-validated, three-dimensional crystal plasticity, finite element study with aluminium alloy single crystals. Representative volume element (RVE) based simulations of single crystalline aluminium alloys (AA-5xxx) with different void geometries and orientations have been performed. Both local and nonlocal crystal plasticity constitutive models have been implemented in a finite element framework and are used to seek new insights into the interrelationships among void growth, initial porosity, initial void size, plastic anisotropy, and local/nonlocal size effects.