Shariati, Behdad
In this thesis, the mechanical properties of old generation ductile iron and new generation SSF materials were compared and investigated by observing cooling behavior. For exploring the thermal analysis, cooling curves were recorded by a temperature scanner to reveal the effect of graphite shape modification by optimum inoculation. Correlations were performed with microstructural features obtained by image analysis and cooling curve analysis. It was observed that inoculation increases the TL and prevents carbide formation in the structure. After inoculation of SSF and old generation DI with 0.5%FeSi, the difference between theoretical eutectic (1152 °C) and the maximum eutectic temperature was measured by thermal analysis. It was found that ΔT changes from 7.4 to -0.8 for SSF and from 4.7 to -0.5 for S.G alloys stand for the increase in eutectic temperature over 1152°C, which is evidence of fully graphite solidification. It was found that the tensile strength decreased from 581 MPa( S.G alloy) to 512 MPa (SSF alloy), but % elongation increased from 10.7(S.G) to 18(SSF) % due to increasing ferrite phase content which is a primary benefit and characteristic of SSF alloy. The tensile strength of DI iron alloys produced in this work was determined to be slightly higher due to the presence of 72 % pearlite compared to 2.13 % in SSF alloys produced. Due to the fully ferritic matrix structure, a 68 % increase in elongation and a 23 % increase in yield strength of SSF alloy compared to DI were achieved in this study.


Rheological properties of extruded dispersions of flaxseed-maize blend
WU, Min; Lİ, Dong; WANG, Li-Jun; Özkan, Necati; Mao, Zhi-Huai (2010-06-01)
Rheological properties of the extruded pastes of various extrusion conditions were investigated by dynamic oscillation and creep-recovery tests. Temperature sweep test showed that the starch gelatinization of non-extruded pastes took place at about 67 degrees C and no gelatinization was observed for the extruded sample. Frequency sweep tests could be represented by a Power law model and the samples showed gel-like behavior since storage modulus was much larger than loss modulus. The creep-recovery data were...
Mechanical properties comparison of strut-based and triply periodic minimal surface lattice structures produced by electron beam melting
Sokollu, Baris; Gulcan, Orhan; Konukseven, Erhan İlhan (2022-12-01)
The aim of this study is to make a comparative assessment of the compression and tensile behavior of two strut -based (body-centered cubic, BCC, and face-centered cubic, FCC) and three triply periodic minimum surfaces (gyroid, primitive, diamond) lattice structures produced by electron beam melting method from Ti6Al4V powder material. Compression and tension tests were performed and compared with finite element analysis results. Moreover, scanning electron microscope analysis for dimensional variation and o...
Thermal stresses in elastic-plastic tubes with temperature-dependent mechanical and thermal properties
Orcan, Y; Eraslan, Ahmet Nedim (2001-11-01)
The thermoelastic-plastic deformations of internal heat-generating tubes are investigated by considering the temperature dependence of the thermal conductivity coefficient, Young's modulus, the coefficient of thermal expansion, and the yield limit of the material. A model describing the elastic-plastic behavior of the tube is developed. The model consists of a system of two second-order ordinary differential equations and a first-order ordinary differential equation involving nonlinear temperature-dependent...
Experimental Investigation of Crack Propagation Mechanisms in Commercially Pure Aluminium Plates
Tekoğlu, C.; Çelik, Ş.; Duran, H.; Efe, M.; Nielsen, K.L. (Elsevier BV; 2019)
The crack surface morphology in tearing of ductile metal plates depends on the mechanical properties, chemical composition and the microstructure of the plate material as well as on the loading conditions and the specimen geometry. This study assesses the crack surface morphologies observed in commercially pure aluminium plates (Al 1050 H14). Mode I tearing was performed in both single and double edge notched tensile test setups with specimens cut from five different plates with different thickness t, viz. ...
Physics Based Formulation of a Cohesive Zone Model for Ductile Fracture
Yalçınkaya, Tuncay (2015-07-01)
This paper addresses a physics based derivation of mode-I and mode-II traction separation relations in the context of cohesive zone modeling of ductile fracture of metallic materials. The formulation is based on the growth of an array of pores idealized as cylinders which are considered as therepresentative volume elements. An upper bound solution is applied for the deformation of the representative volume element and different traction-separation relations are obtained through different assumptions.
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