Technical College Carol I

Bucharest, Romania

Technical College Carol I

Bucharest, Romania
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Jinescu V.V.,Polytechnic University of Bucharest | Nicolof V.-I.,Technical College Carol I | Chelu A.,Polytechnic University of Bucharest | Manea S.-E.,Horia Hulubei National Institute of Physics and Nuclear Engineering
UPB Scientific Bulletin, Series D: Mechanical Engineering | Year: 2015

One analysis the strength of tubular samples and tubular junctions without and with cracks. Non-linear behaviour is considered. Strength calculation has been proposed for: - un-cracked and cracked tubular specimens mixed-mode loaded; - un-cracked and cracked tubular joints mixed-mode loaded. The obtained relationships for strength calculation take into account the deterioration, the residual stress, as well as the scattering of mechanical characteristics involved in the loading process. The relationships proposed in the paper were verified against results reported in literature. © 2015, Politechnica University of Bucharest. All rights reserved.


Jinescu V.V.,Polytechnic University of Bucharest | Nicolof V.-I.,Technical College Carol i | Terodorescu N.,Polytechnic University of Bucharest
International Journal of Damage Mechanics | Year: 2017

The problems of loading superposition of low cycle fatigue, finite cycle fatigue and high cycle fatigue on cracked structure are analyzed. The nonlinear power law behavior of the structure material has been considered. A strength criterion was established for a cracked structure under low cycle fatigue, finite cycle fatigue, and high cycle fatigue loading taking into account the deterioration. On the basis of concept of the specific energy participation and using Basquin's law and Coffin-Manson's law, a general relationship of fatigue life was established in the case of superposition of low cycle fatigue, finite cycle fatigue, and high cycle fatigue loadings on a mechanical structure deteriorated due to cracks. The derived relationships depend on the high cycle fatigue and finite cycle fatigue mean stress and on the low cycle fatigue mean strain, as well as on deterioration. Relationships for the deterioration calculation were established. Experimental work was performed for specimens with cracks, made of steel, statically and cyclically loaded. A numerical example shows how the established relationships may be used. © The Author(s) 2015.


Jinescu V.V.,Polytechnic University of Bucharest | Nicolof V.-I.,Technical College Carol I
Engineering Fracture Mechanics | Year: 2015

New critical strength criteria at the tip of the crack were proposed: - one criterion correlates the stress far away from the crack tip with the stress intensity factor - the other one correlates the stress far away from the crack tip with the crack tip opening displacement. The correlation between the crack tip opening displacement and the strain far away from the crack tip was verified with experimental data from literature for static and fatigue loaded samples. The theoretical relationships were in good agreement with the experimental data. © 2015 Elsevier Ltd.


Jinescu V.V.,Polytechnic University of Bucharest | Chelu A.,Polytechnic University of Bucharest | Teodorescu N.,Polytechnic University of Bucharest | Nicolof V.-I.,Technical College Carol I
Revista de Chimie | Year: 2015

The strength of tubular sample loaded by only one load or simultaneously with several loads is analyzed. Critical stresses and critical loading parameters were introduced and discussed in the case of nonlinear power law behavior. On the basis of principle of critical energy eqs. for superposition of loading effects have been obtained. The influence of deterioration due the cracks has been introduced. The obtained theoretical results were applied to tubular branch junctions and verified against data from literature.


Nicolof V.-I.,Technical College Carol I
Revista de Chimie | Year: 2015

The pressure equipment fatigue loading is analyzed. A general survey of the calculation of pressure vessels cyclically loaded in the Euronorma 13445 and in the ASME Code is presented. Based on the principle of critical energy it was developed a new method of calculation of pressure vessels subject to fatigue.


Iordachescu V.-I.,Technical College Carol I | Sima T.,Polytechnic University of Bucharest
Revista de Chimie | Year: 2015

The paper evaluates: - The damage caused by cracks; - The superposition of effects by using fracture mechanics concepts (the stress intensity factor). In the case of superposition fracture modes I and II, the relation was checked against the experimental literature data.


Jinescu V.V.,Polytechnic University of Bucharest | Nicolop V.-I.,Technical College Carol I | Jinescu C.,Polytechnic University of Bucharest | Chelu A.,Polytechnic University of Bucharest
Revista de Chimie | Year: 2015

The paper outlines the superposition of effects by resorting to the principle of critical energy in both tubular structures as well as in non-Newtonian fluid flow. A relation is proposed for the calculation of critical stress in a cracked specimen, by considering the concept of deterioration; - one determines the amount of deterioration caused to tubular specimens under static loading, depending on the crack geometry and position; - relationships have been proposed for calculating deterioration by considering the crack depth and length. Considerations refer to specimens under one single load (axial force or bending moment) as well as specimens under two simultaneous loads (axial force and bending moment). We put forth a relation for the superposition of the Couette flow effects and the Poiseuille pressure flow effects of a non-Newtonian fluid. The theoretical results have been accounted for by experimental data.

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