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1

Instabilities in membrane tension: Parametric study for large strain thermoplasticity

Mucha M., Wcisło B., Pamin J., Kowalczyk-Gajewska K.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1055--1067

EN

This paper deals with the numerical analysis of localized deformation for a rectangular plate in membrane tension, modelled with large strain thermoplasticity. The aim is to determine the influence of selected factors on the localization phenomena, which can result from geometrical, material, and thermal softening. Two types of boundary conditions are considered: plane stress and plane strain, as well as two yield functions, Huber–Mises–Hencky and Burzyński–Drucker–Prager, with selected values of friction angle. First, isothermal conditions are considered and next, a conductive case with thermal softening is studied. Moreover, three types of plastic behaviour are analysed: strain hardening (with different values of hardening modulus), ideal plasticity, and strain softening. Numerical tests, performed using AceGen/FEM packages, are carried out for the rectangular plate under tension with an imperfection, using three finite element discretizations. The results for plane strain in the isothermal model show that with the decrease of linear hardening modulus, we can observe stronger mesh sensitivity, while for plane stress, mesh sensitivity is visible for all cases. Furthermore, for the thermomechanical model the results also depend on the mesh density due to insufficient heat conduction regularization.

2

On the uniqueness conditions and bifurcation criteria in coupled thermo-elasto-plasticity

Śloderbach Z.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 1

199--227

EN

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.

3

Processing and characterization of cathodic dip coated metal/composite-laminates

Gerstenberger C., Osiecki T., Kroll L., Scholz P., Seidlitz H.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 3

467--472

EN

The current trend shows an increasing demand for novel technologies, that facilitate a functional integration of fiber reinforced polymers (FRP) in metal based structures, especially in automotive industry. To comply with the requirements of large-scale production the use of fiber reinforced thermoplastics in form of hybrid metal/composite-laminates seems advantageous. By targeted exploitation of their high lightweight potential, combined with suitable capabilities for mass production and good damping properties, cost-effective and weight-optimized parts with high stiffness and load capacity can be provided for future applications. As there is little known about the processing and the mechanical properties of thermoplastic based FRP/metal-laminates, the study focuses on the development of novel hybrid laminates with low residual stresses, made of metallic steel sheets and continuous glass or carbon fiber reinforced polyamide 6. In this context, the influence of several pre-operations like sand blasting, cleaning or primer application on the interlaminar shear strength (ILSS) was examined in addition to their resistance to cathodic dip paint treatment.

4

Zamknięty układ sprzężeń termo-sprężysto-plastyczności. Cz. 1 . Zamknięty układ równań i diagram elektów sprzężeń

Śloderbach Z

Energetyka

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2012

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nr 11

751-758

PL

W części pierwszej artykułu wyprowadzono równania pola sprzężonej uogólnionej termoplastyczności na podstawie ujęcia klasycznej termodynamiki procesów nieodwracalnych. Używając przekształceń wprowadzono dwa nowe potencjały termodynamiczne oznaczone odpowiednio przez P i S zależne od wewnętrznych sił termodynamicznych W części pierwszej artykułu wyprowadzono równania pola sprzężonej uogólnionej termoplastyczności na podstawie ujęcia klasycznej termodynamiki procesów nieodwracalnych. Używając przekształceń wprowadzono dwa nowe potencjały termodynamiczne oznaczone odpowiednio przez P i S zależne od wewnętrznych sił termodynamicznych ∏. Do analizy zagadnienia przyjęto dla wszystkich potencjałów ogólną postać, a nie w postaci addytywnej. Uzyskano w ten sposób zamknięty układ sprzężeń termo-sprężysto-plastyczności z elektem sprzężenia spreżysto-plastycznego występującego w materiałach porowatych typu skały, grunty, beton i w niektórych materiałach metalicznych.

EN

In this first part of 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 a two new therm potentials P and S depending upon internal thermodynamic forces ∏ are introduced. The most general form for the all 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 metallic materials.

5

Precyzyjne układy pomiaru wielkości fizycznych w urządzeniu do badania termoplastyczności rud żelaza

Wesołowski M., Więch M., Orzechowski Z.

Elektronika : konstrukcje, technologie, zastosowania

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2010

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Vol. 51, nr 7

228-230

PL

Produkcja stali jest procesem wymagającym stałego monitoringu. Aktualnie, zarówno względy ekonomiczne, jak i ekologiczne wymagają stosowania wielu środków umożliwiających optymalizacje procesu produkcyjnego pod względem maksymalizacji uzysku, jak i minimalizacji kosztów produkcji oraz negatywnego oddziaływania na środowisko naturalne. Względy te wymagają stosowania coraz doskonalszych metod pomiarowych parametrów jakościowych materiałów wsadowych wielkich pieców.

EN

Main domain of this article was put onto measurement precision and results useful in the device for determination of iron ores plasticity. New device, elaborated in Tele- and Radio Research Institute can provide a veryuseful measurement results, by assure a recurrentmeasurement conditions, approximate to real industrial process. Some measurement systems of physical properties and some control systems of the device was discussed in this paper and results were shown.

6

Nowe urządzenia do badania rud żelaza

Więch M., Kret J., Bartusek S., Wolf-Łysiak D.

Elektronika : konstrukcje, technologie, zastosowania

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2010

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Vol. 51, nr 7

225-227

PL

W artykule omówiono nowe urządzenia do pomiaru redukcyjności oraz termoplastyczności rud żelaza, opracowane w Instytucie Tele- i Radiotechnicznym. Szczególną uwagę poświęcono zagadnieniom dokładności pomiaru oraz przydatności wyników uzyskanychw skali mikro-, które powinny reprezentować wyniki otrzymane w warunkach przemysłowych. Przedstawiono także oryginalne rozwiązania konstrukcyjne urządzeń elektrotermicznych.

EN

In the article are presented the new devices for determination reducibility and thermoplasticity of iron ores worked out in Tele- & Radio Research Institute. The considerable amount of thought is given to the measurement precision and usefulness of micro scale results which should represent results obtained in industrial conditions. The orginal construction of electrothermal systems are described also.

7

Generalized thermoelastic plane harmonic waves in materials with voids

Sharma J. N., Kaur D.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 4

1019-1043

EN

The aim of the present paper is to give a detailed account of the plane harmonic generalized thermoelastic waves in solids containing vacuous voids based on the modified fourier law of heat conduction. The general characteristic equation being quartic suggests that there are four longitudinal waves, namely: quasi-elastic [...], quasi-thermal [...], volume fraction [...] and micro-thermal [...], in addition to transverse waves, which can propagate in such solids. The transverse waves get decoupled from the rest of the field quantities and hence remain unaffected due to temperature variation and porosity effects. These waves travel without attenuation and dispersion. The other generalized thermoelastic waves are significantly influenced by the interacting fields and hence suffer both attenuation and dispersion. The general complex characteristic equation has been solved by using descartes algorithm along with irreducible case of cardano's method with the help of demoivre's theorem in order to obtain phase speeds, attenuation coefficients and specific loss factor of energy dissipation. The propagation of waves in non-heat conducting solids has also been discussed. Finally, the numerical solution of the secular equation is carried out to compute phase velocities, attenuation coefficients and specific loss factors of thermoelastic waves which are presented graphically.