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Mucha M.♦, Wcisło B.♦, Pamin J.♦, Kowalczyk-Gajewska K., Instabilities in membrane tension: Parametric study for large strain thermoplasticity,
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2018.01.008, Vol.18, No.4, pp.1055-1067, 2018Abstract: 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 Keywords: Thermoplasticity, Large strains, Strain localization, Parametric study Affiliations:
Mucha M. | - | Cracow University of Technology (PL) | Wcisło B. | - | Cracow University of Technology (PL) | Pamin J. | - | Cracow University of Technology (PL) | Kowalczyk-Gajewska K. | - | IPPT PAN |
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Pamin J.♦, Wcisło B.♦, Kowalczyk-Gajewska K., Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations,
JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.123, Vol.12, No.1, pp.123-146, 2017Abstract: The paper deals with the thermomechanical extension of a large strain hyperelasto-plasticity model and focuses on algorithmic aspects and localization simulations. The formulation includes the degradation of the yield strength due to the increase of an averaged plastic strain measure and temperature, thus, three sources for loss of stability are included in the description. A gradient-enhancement of the model is incorporated through an additional differential equation, but localization is also influenced by heat conduction. The finite element analysis is performed for an elongated plate in plane strain conditions, using different finite elements and values of material parameters related to regularization (internal length scales are related to gradient averaging as well as heat conduction). In particular, the influence of the F-bar enrichment on the simulation results is studied. All computational tests are performed using selfprogrammed user subroutines prepared within a symbolic-numerical tool AceGen which is equipped with automatic differentiation options, allowing for automatic linearization of the governing equations. Keywords: thermoplasticity, softening, gradient averaging, strain localization, automatic linearization, AceGen package Affiliations:
Pamin J. | - | Cracow University of Technology (PL) | Wcisło B. | - | Cracow University of Technology (PL) | Kowalczyk-Gajewska K. | - | IPPT PAN |
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Wcisło B.♦, Pamin J.♦, Kowalczyk-Gajewska K., Gradient-enhanced damage model for large deformations of elastic-plastic materials,
ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.65, No.5, pp.407-428, 2013Abstract: This paper deals with the development of a family of gradient-enhanced elasticity-damage-plasticity models for the simulation of failure in metallic and composite materials. The model incorporates finite deformations and is developed with the assumption of isotropy and isothermal conditions. The gradient enhancement applied to the damage part of the model aims at removing pathological sensitivity to the finite element discretization which can occur due to material softening.
The attention is focused on the algorithmic aspects and on the implementation of the model using AceGen tool. The numerical verification tests of the described model are performed using the Mathematica-based package AceFEM. Particularly, uniaxial tension test for a bar with a variable cross-section and tension of a perforated plate are examined. Keywords: arge strains, damage, plasticity, gradient-enhancement, AceGen package Affiliations:
Wcisło B. | - | Cracow University of Technology (PL) | Pamin J. | - | Cracow University of Technology (PL) | Kowalczyk-Gajewska K. | - | IPPT PAN |
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4. |
Kowalczyk-Gajewska K., Pamin J.♦, Żebro T.♦, Development of gradient-enhanced damage-plasticity formulations for large deformations,
Czasopismo Techniczne. Mechanika, ISSN: 1897-6328, Vol.20, No.105, pp.47-58, 2008 | |
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Żebro T.♦, Kowalczyk-Gajewska K., Pamin J.♦, A geometrically nonlinear model of scalar damage coupled to plasticity,
Czasopismo Techniczne. Mechanika, ISSN: 1897-6328, Vol.20, No.105, pp.251-262, 2008 | |