Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
Browse
3 results
Search Results
Article Constitutive Equation Determination and Dynamic Numerical Modelling of the Compression Deformation of Concrete(Wiley, 2021) Seven, Semih Berk; Çankaya, M. Alper; Uysal, Çetin; Taşdemirci, Alper; Saatci, Selçuk; Güden, MustafaThe dynamic compression deformation of an in-house cast concrete (average aggregate size of 2-2.5 mm) was modelled using the finite element (FE), element-free Galerkin (EFG) and smooth particle Galerkin (SPG) methods to determine their capabilities of capturing the dynamic deformation. The numerical results were validated with those of the experimental split Hopkinson pressure bar tests. Both EFG and FE methods overestimated the failure stress and strain values, while the SPG method underestimated the peak stress. SPG showed similar load capacity profile with the experiment. At initial stages of the loading, all methods present similar behaviour. Nonetheless, as the loading continues, the SPG method predicts closer agreement of deformation profile and force histories. The increase in strength at high strain rate was due to both the rate sensitivity and lateral inertia caused by the confinement effect. The inertia effect of the material especially is effective at lower strain values and the strain rate sensitivity of the concrete becomes significant at higher strain values.Article Citation - WoS: 6Citation - Scopus: 7The Effect of Perforations on the Stress Wave Propagation Characteristics of Multilayered Materials(SAGE Publications Inc., 2016) Taşdemirci, Alper; Kara, AliThe effect of perforated interlayers on the stress wave transmission of multilayered materials was investigated both experimentally and numerically using the Split Hopkinson pressure bar (SHPB) testing. The multilayer combinations consisted of a ceramic face plate and a glass/epoxy backing plate with a laterally constrained low modulus solid or perforated rubber and Teflon interlayer. The perforations on rubber interlayer delayed the stress rise time and reduced the magnitude of the transmitted stress wave at low strains, while the perforations allowed the passage of relatively high transmitted stresses at large strains similar to the solid rubber interlayer. It was concluded that the effect of perforations were somewhat less pronounced in Teflon interlayer configuration, arising from its relatively low Poisson's ratio. It was finally shown that SHPB testing accompanied with the numerical simulations can be used to analyze the effect of compliant interlayer insertion in the multilayered structures. © The Author(s) 2015.Article Citation - WoS: 21Citation - Scopus: 25Quasi-Static and Dynamic Crushing of Empty and Foam-Filled Tubes(Springer Verlag, 2001) Hall, Ian W.; Ebil, Özgenç; Güden, Mustafa; Yu, C.-J.Metallic foam-filled tubes and their empty counterparts have been tested at quasi-static and dynamic strain rates in order to determine their energy absorption capabilities. Data from the Split-Hopkinson Pressure Bar have been used to generate force vs. displacement curves that are somewhat analogous to pseudo-engineering stress-strain curves. Force balance calculations have also been made. These results indicate that, on an equal weight basis, foam-filled tubes offer greater energy absorption capability than empty tubes at quasi-static strain rates. However, the benefit of foam filling does not appear to be extended to strain rates of the order of 200–500 s−1. Force balance calculations are shown to have potential as a method for monitoring the crushing of metallic foams at high strain rate.