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Wyszukujesz frazę "Śloderbach, Z." wg kryterium: Autor


Tytuł:
The influence of thermomechanical coupling on the behaviour of athick-walled metallic tube subjected to internal pressure
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/264368.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
grubościenna rura
naprężenia rzeczywiste
naprężenia szczątkowe
odkształcenia
ciśnienie
thick-walled tube
thermomechanical coupling
actual and residual stresses
strain
pressure
Opis:
In this study, the influence of thermomechanical coupling effect - the effect of thermal expansion due to dissipation of the energy of plastic deformation, with and without taking into account the stored energy of plastic deformation (SEPD) for the distribution of stresses, strains, temperature, the applied pressure and the residual stresses is examined. The residual stresses remain in a thick-walled tube (a cylindrical thick-walled tank) after removing the internal pressure in the process of purely elastic unloading. The analysis is made on the example of an analitycal solution for a thick-walled tube subjected to a quasistatically increasing internal pressure for the case of adiabatic processes (without heat flow). Since the loading with internal pressure is quasi-static (monotonic), then neglecting the process of heat flow can lead to some different results in calculated stresses, deformations, temperature, internal pressure and residual stresses. The calculations for isothermal type of processes of deformations (without heat or ideal cooling) are also performed for the estimation of these differences. The results calculated for the process with heat flow should be intermediate between the values obtained for isothermal and adiabatic processes.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 3; 751-766
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of two conditions of loss of stability in analysis of the tube bending process
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/265422.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
dopuszczalne naprężenia
kąt zginania
warstwa neutralna
kolanko
allowable strains and stresses
bending angles
neutral layer
wall thickness of elbows
Opis:
In this paper, the derivation of expressions for admissible values of strains and stresses for vertex points of layers subjected to tension during tube bending at bending machines is presented. The conditions of the dispersed and located loss of stability of the bent tube were assumed as criteria of instability. The original element of this paper is the extension of the criterion of strain location in a form of possible initiation of a neck or furrow (introduced by Marciniak for thin plates [1]) to bending thin- and thick-walled metal tubes at bending machines. The conditions of the dispersed and localized loss of stability together with formation of the plane state of deformation (PSD) in the plane stress state (PSS) were assumed as the criteria of instability. The calculation results were presented as graphs being useful nomograms. We present also simple examples of calculations of permissible and critical strains and values of bending angles including and not including displacement of the neutral axis y0, during cold bending metal thin-walled tubes at bending machines for bending angles […].
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 200-223
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Closed system of coupling effects in generalized thermo-elastoplasticity
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/266002.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
termodynamika
sprzęgło
naprężenia
odkształcenia
tworzywa sztuczne
thermodynamic potentials
couplings effects
stresses
deformations
temperature
entropy
enthalpy
constitutive and rate equations
yield surface
plastic potential
Opis:
In this paper, the field equations of the generalized coupled thermoplasticity theory are derived using the postulates of classical thermodynamics of irreversible processses. Using the Legendre transformations two new thermodynamics potentials P and S depending upon internal thermodynamic forces Π are introduced. The most general form for all the thermodynamics potentials are assumed instead of the usually used additive form. Due to this assumption, it is possible to describe all the effects of thermomechanical couples and also the elastic-plastic coupling effects observed in such materials as rocks, soils, concretes and in some metalic materials. In this paper not only the usual postulate of existence of a dissipation qupotential (the Gyarmati postulate) is used to derive the velocity equation. The plastic flow constitutive equations have the character of non-associated flow laws even when the Gyarmati postulate is assumed. In general formulation, the plastic strain rate tensor is normal to the surface of the generalized function of plastic flow defined in the the space of internal thermodynamic forces Π but is not normal to the yield surface. However, in general formulation and after the use the Gyarmati postulate, the direction of the sum of the plastic strain rate tensor and the coupled elastic strain rate tensor is normal to the yield surface.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 461-483
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A derivation of the generalized model of strains during bending of metal tubes at bending machines
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/955183.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
zginanie
rura metalowa
giętarka
bending
metal tubes
bending machine
strains
neutral axis
Opis:
According to the postulate concerning a local change of the “actual active radius” with a bending angle in the bend zone, a generalized model of strain during metal tube bending was derived. The tubes should be subjected to bending at tube bending machines by the method of wrapping at the rotating template and with the use of a lubricated steel mandrel. The model is represented by three components of strain in the analytic form, including displacement of the neutral axis. Generalization of the model during bending metal tubes at the tube bending machines as compared with the existing papers (Śloderbach, 1999; Śloderbach and Rechul, 2000) consists in including the neutral axis displacement and possibility of determination of strains at each point along the thickness of the wall of the bent tube in the bending and bend zone. The derived scheme of strain satisfies initial and boundary kinematic conditions of the bending process, conditions of continuity and inseparability of strains. The obtained analytic expressions can be classified as acceptable from the kinematic point of view.
Źródło:
International Journal of Applied Mechanics and Engineering; 2014, 19, 1; 145-163
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of the parameters of vibrations during dynamic balancing of the fan rotor according to Polish and International Standards
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/947331.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
parametry drgań
wirnik wentylatora
normy ISO
wyważanie dynamiczne
parameters of vibrations
ISO standards
fan rotor
dynamic forces
dynamic balancing
Opis:
In the paper a procedure and methodology of acceptable calculations of powers, displacements (of amplitudes) and velocities of pulses according to ISO standards depending on the rotational speeds (frequencies) of rotor during attempts of dynamic breaking down taking into account effectiveness of vibration isolation were described. The proposed method is regarding one-sidedly hung rotors appearing in such appliances as rotors of fans, blowers, pumps and others. As permissible parameters of pulses values which are given in international standards PN-ISO-10816-1:1998P and PN-ISO-7919-1:2001 were assumed. Calculations were compared in the form of tables and they depicted with relevant graphs which have the character of useful nomograms. Also, recommendations for the design of the foundations and guidelines related to dimensions of the foundation, the weight and the way of fixing the device were given. In the end also closing remarks and conclusions were given.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 2; 473-483
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized model of strains during bending of metal tubes in bending machines
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/279709.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
tubes bending
deformations
bending angle
thickness of the wall
neutral axis
Opis:
According to the postulate concerning a local change of the “actual active radius” with a bending angle in the bent zone, a generalized model of strain during bending of ametal tube has been derived. The considered tubes should be subjected to bending in tube bending machines by the method of wrapping on a rotating template and with the use of a lubricated steel mandrel. The model is represented by three components of strain in the analytical form, including displacement of the neutral axis. Generalization of the model of metal tubes in the existing papers consists in including the displacement of the neutral axis and the possibility of determination of strains at each point along the thickness of the wall of the bent tube in the bending zone. The derived scheme of strain satisfies initial and boundary kinematic conditions of the bending process, conditions of continuity and inseparability of strains. The obtained analytical expressions can be classified as acceptable from the kinematic point of view.
Źródło:
Journal of Theoretical and Applied Mechanics; 2014, 52, 4; 1093-1106
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of strains and thicknesses of pipe elbows on the basis of expressions resulting from the EU-Directive for the case of large and small deformations
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/264378.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
EU Directive
required thicknesses of pipe elbows
pipe bending processes
relative and logarithmic measures of deformation
required initial thickness of a bent tube
Dyrektywa UE
kolanko rurowe
rura
Opis:
The relations to calculate the maximum value of strains in processes of bending tubes on benders, in stretched layers of tubes, are presented in this work on the basis of the EU-Directive concerning production of pressure equipment. It has been shown that for large deformations that occur during bending of the pipes on knees, logarithmic strain measures (real) and relative strain measures give different values of strain but equal wall thicknesses in the bending zone. Logarithmic measures are frequently used in engineering practice and are valid for large and small deformations. Reverse expressions were also derived to calculate the required initial wall thickness of the tube to be bent, in order to obtain the desired wall thickness of the knee after bending.
Źródło:
International Journal of Applied Mechanics and Engineering; 2017, 22, 4; 1113-1127
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Derivation of relations and analysis of tube bending processes using discontinuous fields of plastic strains. Part I. Derivation of geometric-analytic relationships
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/264482.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
bending tubes
three simplifications
strains
wall thickness
discontinuous strain fields
naprężenia
kinematyka
gięcie rur
Opis:
The generalized strain scheme in bending metal tubes at bending machines with the use of a mandrel presented in Śloderbach (1999; 2002; 20131,2; 2014) satisfies initial and boundary kinematic conditions of bending, conditions of continuity and inseparability of strains. This paper introduces three formal simplifications gradually imposed into forms of principal components of the generalized strain model giving suitable simplifications of the 1st, 2nd and 3rd types. Such mathematical simplifications cause that the obtained strain fields do not satisfy the condition of consistency of displacements and strain continuity. The simplified methods determine safer values of the wall thickness than those from the generalized continuous strain scheme. The condition of plastic incompressibility was used for the derivation of an expression for distribution of Wall thickness of the bent elbow in the layers subjected to tension and compression for three examples of discontinuous kinematic strain fields.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 2; 417-426
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conditions of stability loss during the test of hydraulic forming of drawpieces. Part II. Discussion and analysis of the results
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/265430.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
hydraulic forming
stability loss
boundary strains
height of the drawpiece
normal and plane anisotropy
odkształcenia plastyczne
utrata stabilności
wytłoczki
Opis:
This part of the paper contains the calculation results presented in the form of suitable diagrams and tables. The calculations were made according to the relationships obtained in Part I devoted to a laboratory test of hydraulic forming for some chosen engineering conditions of stability loss. The influence of the coefficient of material hardening, the coefficient of normal anisotropy and the coefficients of plane anisotropy on acceptable plastic strains and heights of the formed drawpieces corresponding to a given condition of stability loss was tested, too.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 928-938
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the uniqueness conditions and bifurcation criteria in coupled thermo-elasto-plasticity
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/266253.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
bifurcation of the equilibrium state
conditions and criteria of uniqueness
boundary-value problem
generalized coupled thermo-elasto-plasticity
comparison bodies
family of local conditions of uniqueness
parameter of the optimization
termoplastyczność
elastoplastyczność
odkształcenie plastyczne
Opis:
The global and local conditions of uniqueness and the criteria excluding a possibility of bifurcation of the equilibrium state for small strains are derived. The conditions and criteria are derived analyzing the problem of uniqueness of solution of the basic incremental boundary problem of coupled generalized thermo-elasto-plasticity. This paper is a continuation of some previous works by the author, but contains new derivation of the global and local criteria excluding a possibility of bifurcation of the equilibrium state for a comparison body dependent on statically admissible fields of stress velocity. All the thermal elastoplastic coupling effects, non-associated laws of plastic flow and influence of plastic strains on thermoplastic properties of a body were taken into account in this work. Thus, the mathematical problem considered here is not a self-conjugated problem. The paper contains four Appendices A, B, C and D where the local necessery and sufficient conditions of uniqueness have been derived.
Źródło:
International Journal of Applied Mechanics and Engineering; 2017, 22, 1; 199-227
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

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