TRANSIENT ANALYSIS OF GEOMETRICALLY NON-LINEAR TRUSSES CONSIDERING COUPLED PLASTICITY AND DAMAGE

TRANSIENT ANALYSIS OF GEOMETRICALLY NON-LINEAR TRUSSES CONSIDERING COUPLED PLASTICITY AND DAMAGE

Muñoz-Rojas, P. A.; Suzuki, J. L.

Full Article:

The fracture of ductile materials is usually preceded by considerable levels of plastic strain. After a first stage in which plastic strain strengthens the material due to the introduction and increase of dislocations (hardening), a degradation phenomenon begins to take place due to the nucleation of microcracks and microvoids. The nucleation, growth and coalescence of these defects can be modeled using the concepts of Continuum Damage Mechanics. In this theory, a continuous damage variable is defined, which evolves coupled to plastic strain until attaining a critical value associated to rupture. Several damage models have been proposed for ductile materials, two of the most important being attributed to Gurson and to Lemaitre. This work evaluates the effect of Lemaitre’s damage model when applied to 3D trusses subjected to geometrical nonlinearities including inertial forces. To this end, two different damage evolution laws found in the literature are studied and compared. Special attention is given to unstable problems such as snap-through, in which results show that the effect of inertial forces is predominant. Furthermore, it becomes evident that for a realistic description of damage evolution and failure prediction, a different treatment must be given to tensile and compressive states. The work is closed by the discussion of damping effects on the damaged dynamic problem. It should be remarked that the evaluation of coupled plasticity and damage including geometrical nonlinearities, inertial forces and damping is a complex problem. Hence, setting these phenomena in a simple 3D truss framework makes it possible to focus on the description of physical behavior rather than on element technology complexities. This allows a clear understanding of some effects of Lemaitre’s damage, paving the way for implementations using 2D and 3D continuum finite elements.

The fracture of ductile materials is usually preceded by considerable levels of plastic strain. After a first stage in which plastic strain strengthens the material due to the introduction and increase of dislocations (hardening), a degradation phenomenon begins to take place due to the nucleation of microcracks and microvoids. The nucleation, growth and coalescence of these defects can be modeled using the concepts of Continuum Damage Mechanics. In this theory, a continuous damage variable is defined, which evolves coupled to plastic strain until attaining a critical value associated to rupture. Several damage models have been proposed for ductile materials, two of the most important being attributed to Gurson and to Lemaitre. This work evaluates the effect of Lemaitre’s damage model when applied to 3D trusses subjected to geometrical nonlinearities including inertial forces. To this end, two different damage evolution laws found in the literature are studied and compared. Special attention is given to unstable problems such as snap-through, in which results show that the effect of inertial forces is predominant. Furthermore, it becomes evident that for a realistic description of damage evolution and failure prediction, a different treatment must be given to tensile and compressive states. The work is closed by the discussion of damping effects on the damaged dynamic problem. It should be remarked that the evaluation of coupled plasticity and damage including geometrical nonlinearities, inertial forces and damping is a complex problem. Hence, setting these phenomena in a simple 3D truss framework makes it possible to focus on the description of physical behavior rather than on element technology complexities. This allows a clear understanding of some effects of Lemaitre’s damage, paving the way for implementations using 2D and 3D continuum finite elements.

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DOI: 10.5151/meceng-wccm2012-16750

Referências bibliográficas

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Como citar:

Muñoz-Rojas, P. A.; jorge luis suzuki; "TRANSIENT ANALYSIS OF GEOMETRICALLY NON-LINEAR TRUSSES CONSIDERING COUPLED PLASTICITY AND DAMAGE", p-322-341. In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1]. São Paulo: Blucher, 2014.
ISSN 23580828, DOI 10.5151/meceng-wccm2012-16750