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: 1Citation - Scopus: 1Epoxy Matrix Nano Composites: Modulus, Strength and Ductility Enhancement Through Auxeticity of Α-Cristobalite Filler(Elsevier, 2023) Güden, Mustafa; Ülker, Sevkan; Movahedi, NimaThe negative Poisson's ratio (NPR) nano-size ?-Cristobalite particle/epoxy composites were prepared and tensile tested. The elastic modulus and strength of the composites were improved as the particle volume fraction increased from 0 to 0.02. Unlike the conventional particle reinforced composites, the fracture strain increased with the nano ?-Cristobalite addition, an effect which was ascribed to the intrinsic NPR behavior of the filler. © 2023 Elsevier B.V.Article Citation - WoS: 54Citation - Scopus: 59Orientation Dependent Tensile Properties of a Selective-Laser 316l Stainless Steel(Elsevier, 2021) Güden, Mustafa; Yavaş, Hakan; Tanrıkulu, Ahmet Alptuğ; Taşdemirci, Alper; Akın, Barış; Enser, Samed; Karakuş, Ayberk; Arslan Hamat, BurcuThe effect of specimen inclination angle with respect to building direction on the tensile properties of a selective laser melt 316L alloy was investigated. Tensile test specimens were fabricated with the angles between 0 degrees to 90 degrees at 15 degrees intervals using a rotation scanning. In addition, 316L alloy test specimens were generated in the ANSYS 2020R1 additive module and tensile tested in LS-DYNA in order to determine the effect of residual stresses on the tensile strengths. The microscopic analysis revealed a strong < 110 > fiber texture orientation along the building direction (the loading axis of 0 degrees inclined specimens) and a weak 111 texture or nearly random distribution of directions in the normal to the building direction (tensile loading axis of 90 degrees inclined specimens). The yield and tensile strength increased and ductility decreased with increasing inclination angle. The strength variation with the inclination angle was shown well-fitted with the Tsai-Hill failure criterion. Although, the used numerical models indicated an inclination-dependent residual stress, the difference in the residual stresses was much lower than the difference in the strengths between 0 degrees and 90 degrees inclined specimens. Predictions showed a lower twinning stress in 0 degrees inclined specimens due to < 110 > fiber texture orientation in the tensile axis. The fiber texture resulted in extensive twinning; hence, higher ductility and tension-compression asymmetry in 0 degrees inclined specimens. Based on these results, the variations in the strength and ductility of tested SLM-316L specimens with the inclination angle was ascribed to the variations in the angle between the fiber texture orientation and loading axis.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. © 2020Article Citation - WoS: 4Citation - Scopus: 4The Effect of Cell Wall Material Strain and Strain-Rate Hardening Behaviour on the Dynamic Crush Response of an Aluminium Multi-Layered Corrugated Core(Taylor and Francis Ltd., 2021) Güden, Mustafa; Canbaz, İlkerThe effect of the parameters of the Johnson and Cook material model on the direct impact crushing behaviour of a layered 1050 H14 aluminium corrugated structure was investigated numerically in LS-DYNA at quasi-static (0.0048 m s(-1)) and dynamic (20, 60, 150 and 250 m s(-1)) velocities. Numerical and experimental direct impact tests were performed by lunching a striker bar onto corrugated samples attached to the end of the incident bar of a Split Hopkinson Pressure Bar set-up. The numerical impact-end stress-time and velocity-time curves were further compared with those of rigid-perfectly-plastic-locking (r-p-p-l) model. Numerical and r-p-p-l model impact-end stress analysis revealed a shock mode at 150 and 250 m s(-1), transition mode at 60 m s(-1) and quasi-static homogenous mode at 20 m s(-1). The increase of velocity from quasi-static to 20 m s(-1) increased the numerical distal-end initial peak-stress, while it almost stayed constant between 20 and 250 m s(-1) for all material models. The increased distal-end initial peak-stress of strain rate insensitive models from quasi-static to 20 m s(-1) confirmed the effect of micro-inertia. The numerical models further indicated a negligible effect of used material models on the impact-end stress of investigated structure. Finally, the contribution of strain rate to the distal-end initial peak-stress of cellular structures made of low strain rate sensitive Al alloys was shown to be relatively low as compared with that of strain hardening and micro-inertia, but it might be substantial for the structures constructed using relatively high strain rate sensitive alloys.