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: 2Citation - Scopus: 2A Comprehensive Study on the Effectiveness of the Stress and Damage Model Parameters in Predicting the Compression Fracture Behavior of Selective Laser Melted AlSi10Mg BCC Lattices(Elsevier B.V., 2025) Guden, Mustafa; Erten, Hacer Irem; Gorguluarslan, Recep M.; Gulletutan, Umut Can; Dagkolu, Akin; Gokdag, Istemihan; Namazov, SubhanThe Johnson and Cook (JC) stress and damage model parameters determined from the machined bulk cylindrical specimens and as-built struts through tension and compression tests were used to model quasi-static compression behavior of selective laser melt-fabricated AlSi10Mg alloy lattices. The lattices had the same cell size (10 mm) and strut diameter (1 mm), but different number of cells (2 x 2 x 2, 10 x 10 x 2 and 5 x 5 x 5) and geometries (sandwich and cubic). Four different sets of JC damage model parameters (brittle and ductile notch-insensitive and compression and tension notch-sensitive) were further implemented in the lattice compression numerical models. The brittle damage model parameters and smaller mesh sizes resulted in cracking the face-sheet corner strut nodes before the occurrence of a bending-dominated initial peak stress. The notch-sensitive damage model parameters exhibited no bent-strut fracture in the middle layers of the lattices and increased the crack initiation strains as compared with the notch-insensitive damage model parameters. Despite significant variations in the initial peak stresses of the tested 2 x 2 x 2 and 10 x 10 x 2 lattices, the implication of the strut micro-tension stress model together with the compression notch-sensitive damage model parameters using 0.25 mm mesh size conservatively approximated the experimental deformation stresses while the machined bulk specimen tensionstress model over predicted the experimental stresses. On the other side, the strut stress model with 0.15 mm mesh size accurately predicted the experimental diagonal shear/fracture mode of struts with a slightly higher numerical initial peak stress. The compression tests on the strut specimens extracted from the as-built lattices yielded similar stress model parameters with the micro-tension tests. The differences between the initial peak stresses of the investigated sandwich and cubic lattices were further explained by the differences in the lattice boundary conditions.Article Citation - WoS: 9Citation - Scopus: 10Cyclic Compressive Behavior of Hybrid Frp-Confined Concrete(American Society of Civil Engineers, 2021) İspir, Medine; Dalgıç, Korhan Deniz; İlki, AlperThe aim of this study is to define the cyclic axial behavior of hybrid FRP (fiber reinforced polymer)-confined concrete based on the results of an experimental study presented here. Two different types of fiber sheets with different ultimate tensile strain capacities were used together in a suitable epoxy resin matrix to confine concrete. The inner and outer jackets of the concrete confinement were constituted with carbon (or glass) sheets with a relatively low tensile strain capacity and polyethylene terephthalate (PET) sheets with a high tensile strain capacity. PET fibers, which are a relatively new type of fiber, are made from recycled plastics. By varying the number of layers of the outer fiber sheet, different combinations were formed for the hybrid jackets. To characterize the cyclic axial behavior of hybrid FRP-confined concrete, experimental data were utilized to obtain the axial stress-strain relationship and dilation behavior. Based on the results, a stress-strain model for the envelope curve of the cyclic response of hybrid FRP-confined concrete is proposed.Article Citation - WoS: 23Citation - Scopus: 24Determination of the Material Model and Damage Parameters of a Carbon Fiber Reinforced Laminated Epoxy Composite for High Strain Rate Planar Compression(Elsevier Ltd., 2021) Shi, C.; Guo, B.; Sarıkaya, Mustafa; Çelik, Muhammet; Chen, P.; Güden, MustafaThe progressive failure of a 0°/90° laminated carbon fiber reinforced epoxy composite was modeled in LS-DYNA using the MAT_162 material model, including the strain rate, damage progression and anisotropy effects. In addition to conventional standard and non-standard tests, double-shear and Brazilian tests were applied to determine the through-thickness shear modulus and the through-thickness tensile strength of the composite, respectively. The modulus reduction and strain softening for shear and delamination parameters were calibrated by low velocity drop-weight impact tests. The rate sensitivities of the modulus and strength of in-plane and through-thickness direction were determined by the compression tests at quasi-static and high strain rates. The fidelity of the determined model parameters was finally verified in the in-plane and through-thickness direction by the 3D numerical models of the Split Hopkinson Pressure Bar compression tests. The numerical bar stresses and damage progressions modes showed acceptable correlations with those of the experiments in both directions. The composite failed both numerically and experimentally by the fiber buckling induced fiber-matrix axial splitting in the in-plane and the matrix shear fracture in the through-thickness direction. © 2020