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Kormanikova E.,TU of Kosice | Mamuzic I.,Croatian Metallurgical Society
Metalurgija | Year: 2011

The shear deformation laminate theory is very useful for the calculation of the sandwich composites. Sandwich can be defined as a special laminate with three layers and therefore can be modeled using shear deformation laminate theory by neglecting of membrane and bending deformations in the core and the shear deformation in the facings.

Kormanikova E.,TU of Kosice | Mamuzic I.,Croatian Metallurgical Society
Metalurgija | Year: 2011

The paper is aimed on laminate optimization subjected to maximum strain criterion. The optimization problem is based on the use of continuous design variables. The thicknesses of layers with the known orientation are used as design variables. The optimization problem with strain constraints are formulated to minimize the laminateweight. The design of the final thickness is rounded off to integer multiples of the commercially available layer thickness.

Kuncicka L.,VSB - Technical University of Ostrava | Stepan P.,VSB - Technical University of Ostrava | Kliber J.,VSB - Technical University of Ostrava | Mamuzic I.,Croatian Metallurgical Society
Metalurgija | Year: 2014

Ti-Nb alloys are of a large potential for industrial, as well as biomedical utilisation. Oxygen content in the alloy is a parameter infl uencing its properties and cannot be neglected. The main focus of this paper is on observation of infl uence of annealing time on oxygen content in the structure of Ti - 20,7 (at.)% Nb alloy. Four groups of the samples were annealed at the temperature of 800 °C from 15 to 60 minutes with 15 min. step. As it was proven by the analysis, the oxygen content increased with increasing annealing time. Moreover, microhardness measurements showed increasing trend of HV microhardness value with increasing oxygen content.

Michel J.,Technical University of Kosice | Bursak M.,Technical University of Kosice | Mamuzic I.,Croatian Metallurgical Society
Metalurgija | Year: 2012

Mechanical properties of a steam tube made of CrMo creep resistant steel are analysed in this contribution after up to 2,6·105 hours service life in creep conditions at temperature 530 °C and calculated stress level in the tube wall 46,5 MPa. During service life there were in the steel gradual micro structure changes, first pearlite spheroidization, precipitation, coaugulation and precipitate coarsening. Nevertheless the strength and deformation properties of the steel (Re, Rm, A5, Z), and the resistance to brittle fracture and the creep strength limit, were near to unchanged after 2,1·105 hours in service. The steam tube is now in service more than 2,6·105 h.

Prokhorenko V.M.,Kharkiv Polytechnic Institute | Perepichay A.O.,Kharkiv Polytechnic Institute | Mamuzic I.,Croatian Metallurgical Society | Cikic A.,Technical college in Bjelovar
Metalurgija | Year: 2013

The paper proposes a variant for solving the problem of reduction of longitudinal residual stresses in near-root region of a circumferential welded joint of section of steam pipeline by FEM simulation of the stress-strain state of repaired section of a circumferential weld in the zone of lack of root penetration on a thin-wall shell of 89 mm diameter and 6 mm wall thickness from steel 20. The result of solving the problem is total distribution of stresses and residual plastic deformations in the repaired zone.

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