sami karadeniz - Academia.edu (original) (raw)

Papers by sami karadeniz

SSRN Electronic Journal, 2022

Rubber type materials are preferred because they are suitable for use in many engineering applica... more Rubber type materials are preferred because they are suitable for use in many engineering applications besides their elasticity. EPDM rubber show outstanding heat, ozone and weather resistance and has excellent electrical properties. Therefore this rubber as an elastomer is an engineering material that has wide range of applications in industry such as door and window seals, radiator, garden and heating hoses, tubing, washers, belts, electrical insulation, roofing membrane and rubber mechanical goods. In this works, the stress relaxation behaviour of EPDM rubber at the room temperature were experimentally investigated. Applied to the hardness EPDM samples were subjected to different loading programs. In addition, for the loading programs that were implemented, it is shown that for the EPDM rubbers tested the stress relaxation curves obtained at different stretch ratios may be represented by a single representative curve for the specimens having the same hardnesses. gibi çok yaygın u...

Applied Sciences, 2020

Ultra-high-strength concrete is a newly developed construction material that has a minimum 120 MP... more Ultra-high-strength concrete is a newly developed construction material that has a minimum 120 MPa or higher compressive strength. Recently, the usage of high-strength and ultra-high-strength concretes has become widespread due to the enhancement of the concrete technology. Many civil engineering structures constructed by using concrete materials are usually subjected to, in addition to static loads, dynamic loads due to earthquakes, wind and storm, impact and blast, which take place under high energy and high strain rate values. The effects of such loadings on the structure must be understood thoroughly. In recent years, the withstanding of a structure on these loading conditions has become a crucial issue for its impact on the economy and human safety. One of the approaches to fulfill these requirements is to develop high-strength or ultra high-strength concretes (UHSCs). In this study, an ultra-high-strength concrete with a compressive strength of 135 MPa was designed and develop...

Journal of Materials Engineering and Performance, 2018

Micro-lattice structures manufactured using the selective laser melting (SLM) process provides th... more Micro-lattice structures manufactured using the selective laser melting (SLM) process provides the opportunity to realize optimal cellular materials for impact energy absorption. In this paper, strain rate-dependent material properties are measured for stainless steel 316L SLM micro-lattice struts in the strain rate range of 10−3 to 6000 s−1. At high strain rates, a novel version of the split Hopkinson Bar has been developed. Strain rate-dependent materials data have been used in Cowper–Symonds material model, and the scope and limit of this model in the context of SLM struts have been discussed. Strain rate material data and the Cowper–Symonds model have been applied to the finite element analysis of a micro-lattice block subjected to drop weight impact loading. The model output has been compared to experimental results, and it has been shown that the increase in crush stress due to impact loading is mainly the result of strain rate material behavior. Hence, a systematic methodology has been developed to investigate the impact energy absorption of a micro-lattice structure manufactured using additive layer manufacture (SLM). This methodology can be extended to other micro-lattice materials and configurations, and to other impact conditions.

Thin-Walled Structures, 2008

This paper deals with the issue of a trigger design and its performance. In this respect, a numer... more This paper deals with the issue of a trigger design and its performance. In this respect, a numerical investigation is carried out to study the effects of the geometrical features of a bump type trigger on the crush behavior of an energy absorbing member subjected to axial impact loading. The member was constructed by joining a top hat profile with a flat lid. The trigger was considered to be a bump with a semi-circular cross section on the hat profile. The finite element solver, LS-DYNA was used in all crush simulations. As a result, the introduction of the trigger was found to be effective on the peak crush force and the energy absorption capability of the member under axial impact loading. It was also shown that the crush response could be controlled by varying the location and the geometry of the trigger.

Rubber Chemistry and Technology, 2006

To describe the elastic behavior of rubber-like materials, numerous specific forms of strain ener... more To describe the elastic behavior of rubber-like materials, numerous specific forms of strain energy functions have been proposed in the literature. This bibliography provides a list of references on the strain energy functions for rubber-like materials on isothermal condition using the phenomenological approach. The published works, either containing the strain energy function proposals or the discussions on such proposals, based upon the phenomenological approach, are classified.

Materials Science and Engineering: A, 2013

ABSTRACT Recently, some published studies have shown that laser melting method can be an impressi... more ABSTRACT Recently, some published studies have shown that laser melting method can be an impressive way for periodic metallic micro-cellular structures with the satisfying requirements to be built. In this respect, this study deeply focuses on examining the experimental static behaviours of stainless steel micro-lattice structures manufactured with the laser melting method for both different cell topologies and loading scenarios such as compression, shear, tension and combined loadings. The results show that the two major parameters characterising the mechanical behaviours of these structures are the relative density and cell topology, which govern the altitude of stress–strain curve and collapse mechanism. Also, pure shear behaviours are unpredictable and have no repeatability due to the complex and highly imperfect surfaces of micro-struts and cells. On the contrary, the compression tests show a large repeatability and stability.

International Journal of Mechanical Sciences, 1996

In this paper, the effects of bearing and housing elasticity on the stress fields, which could re... more In this paper, the effects of bearing and housing elasticity on the stress fields, which could result in surface fatigue in journal bearings, have been investigated. The parameters such as pressure gradient, flexibilities of backing and housing materials, presence of oil grooves, faulty or nonuniform housing supports and non-uniform temperature distributions have been individually considered as the sources of stresses in journal bearings. A parametric analysis of these has been carried out. The geometrical and physical interactions, that would affect the formation and magnitudes of tensile surface stresses to which the bearing alloys are particularly sensitive, have been investigated for both rigid and elastic housing conditions.

International Journal of Mechanical Sciences, 2009

In this paper the influences of residual effects of a deep drawing forming process on the axial q... more In this paper the influences of residual effects of a deep drawing forming process on the axial quasi-static crash behaviour of straight thin-walled top-hat section were numerically investigated. The residual forming data on the plastic strains, residual stresses and thickness variations were transferred to crash models, which include both deformed and nominal meshes. The influence of spring-back or spring-in on