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International Journal for Multiscale Computational Engineering
IF: 1.016 5-Year IF: 1.194 SJR: 0.452 SNIP: 0.68 CiteScore™: 1.18

ISSN Print: 1543-1649
ISSN Online: 1940-4352

International Journal for Multiscale Computational Engineering

DOI: 10.1615/IntJMultCompEng.v8.i1.40
pages 37-60

Softening Gradient Plasticity: Analytical Study of Localization under Nonuniform Stress

Milan Jirasek
Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic
Jan Zeman
Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Thakurova 7,166 29 Prague 6, Czech Republic; Centre of Excellence IT4Innovations, VSB-TU Ostrava, 17 listopadu 15/2172 708 33 Ostrava-Poruba, Czech Republic
Jaroslav Vondrejc
Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic

ABSTRACT

Localization of plastic strain induced by softening can be objectively described by a regularized plasticity model that postulates a dependence of the current yield stress on a nonlocal softening variable defined by a differential (gradient) expression. This paper presents analytical solutions of the one-dimensional localization problem under certain special nonuniform stress distributions. The one-dimensional problem can be interpreted as describing either a tensile bar with a variable cross section or a beam subjected to a nonuniform bending moment. Explicit as well as implicit gradient formulations are considered. The evolution of the plastic strain profile and the shape of the load-displacement diagram are investigated. It is shown that even if the local constitutive law exhibits softening right from the onset of yielding, the global load-displacement diagram has a hardening part. The interplay between the internal length scales characterizing the material and the geometry is discussed.

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