Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
Search Results
Article Citation - WoS: 18Citation - Scopus: 19The Impact Response of a Nomex® Honeycomb Core/E-glass Composite Sandwich Structure To Increasing Velocities: Experimental and Numerical Analysis(Elsevier, 2023) Çelik, Muhammet; Taşdemirci, Alper; Güden, Mustafa; Güden, Mustafa; Sarıkaya, Mustafa; Taşdemirci, Alper; Genç, Cem; Ersoy, Kurtuluş; Serin, Özgür; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe impact response of an E-glass fiber reinforced epoxy/Nomex® honeycomb core sandwich was investigated both experimentally and numerically at increasing velocities through concentrated quasi-static indentation force (CQIF), low velocity impact (LVI) and high velocity impact (HVI) tests. The composite face sheets and core were modelled using MAT_162 and MAT_026 homogenized material model in LS-DYNA, respectively. The experimental and numerical LVI test forces corresponding to core crushing and face sheet penetration were shown to be higher than those of the CQIF tests and increased as the impactor velocity increased. The increase of the impact forces at increasing velocities was largely ascribed to the inertia and the strain rate sensitive fracture strength of the composite sheets. The core shearing was detected in the CQIF and LVI tests both experimentally and numerically. It was also detected in the HVI tests at the velocities less than 20 m s?1. The deformation in the HVI tests at and above ? 29.4 m s?1 was highly localized in the impact area with no core shearing and a large delamination damage area at the front face sheet. The force enhancement due to the micro-inertia of the core deformation was shown to be not significant at the studied velocities. © 2023 Elsevier LtdArticle Citation - WoS: 12Citation - Scopus: 17Development of the Johnson-Cook Flow Stress and Damage Parameters for the Impact Response of Polycarbonate: Experimental and Numerical Approach(Elsevier, 2023) Sarıkaya, Mustafa; Güden, Mustafa; Güden, Mustafa; Taşdemirci, Alper; Kambur, Çağdaş; Çankaya Özbek, Sevim; Taşdemirci, Alper; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe Johnson and Cook (JC) flow stress and damage model parameters of a polycarbonate (PC) plate were determined by the mechanical tests and numerical simulations of the tests. The experimental tests included quasi-static and high strain rate tension and compression, quasi-static notched-specimen tension, quasi-static indentation (QSI), low velocity impact (LVI) and projectile impact (PI). Initially, five different quasi-static flow stress-strain equations were extracted from the experimental and numerical tests. The flow stress equa-tion determined from the experimental average true stress-true strain curve well agreed with the effective stress -strain obtained from the quasi-static numerical tension test. The numerical QSI force-displacement curve based on the experimental average true stress-true strain equation was further shown to be very similar to that of the experiment. The LVI and PI test simulations were then continued with the experimental average true stress-true strain equation using five different flow stress-strain rate relations: JC, Huh and Kang (HK), Allen-Rule and Jones (ARJ), Cowper-Symonds (CS) and the nonlinear rate approach (NLA). The rate sensitivity parameters of these relations were extracted from the quasi-static and high strain rate tests. The LVI test simulations using the stress -strain rate relations exhibited force-displacement curves higher than those of the experiments. The detected almost no strain rate sensitivity in the LVI tests was ascribed to low strain rate dependency of the flow stress at these intermediate strain rates and large strains involved. On the other side, all the stress-strain rate relations investigated nearly predicted the experimental damage types: dishing at 100 and 140 m s-1 and petalling at 160 m s- 1, except the CS relation which predicted the fracture of the plate at 140 m s-1. The experimental average projectile exit velocity at 160 m s- 1 was further well predicted by the used stress-strain rate relations while the experimental average petal thicknesses were under estimated by the models. The absorbed energy at 160 m s-1 PI test was determined 1.6 times that of the QSI test, which proved an increased energy absorption capability of the tested PC at the investigated impact velocities.