Search results for " Strain localization"
showing 5 items of 5 documents
A phase-field model for strain localization
2018
Strain localization in quasi-brittle materials occurs when a material is subjected to a high level of mechanical solicitations and inelastic strains develop in relatively narrow zone where micro-cracks appear. The gradual evolution of the micro-cracks results in the formation of localized bands up to the development of stress-free cracks. The localized zone or plastic band is generally associated to a faster growth of strain and is characterized by inelastic phenomena such as opening and propaga- tion of cracks, initiation and growth of voids. Conversely, outside of this zone, the material unloads elastically. Extensive research has been carried out to address issues related to the modeling…
CRACK PROPAGATION IN FINITE ELEMENTS AUGMENTED WITH EMBEDDED INTERPHASES
2022
In the FE analysis of quasi-brittle materials, one of the main issues is how to correctly capture cracks propagation. In particular, under specific load intensity, strains progressively localize in narrow bands, leading to a global nonlinear softening response until collapse. A variety of FE models have been proposed, which may be separated in two main groups: discrete crack models and continuous models. Discrete crack models introduce a discontinuity along the inter-element boundaries or inside elements (intra-element discontinuity). Continuous models modify the constitutive relations of the local material to better describe its behaviour in presence of a fracture. In the framework of intr…
Some observations on the regularizing field for gradient damage models
2000
Gradient enhanced material models can potentially preserve well-posedness of incremental boundary value problems also after the onset of strain softening. Gradient dependent constitutive relations are rooted in the assumption that some scalar or tensor field, which appears in the yield function, has to be enriched by adding a term involving its second-order gradient field. For gradient-dependent plasticity this term is universally accepted to be the equivalent plastic strain. For gradient-dependent damage models different choices have been presented in the literature. They all possess the desired regularization of the solution, but they are not identical as regards the structural response. …
Finite elements augmented with embedded interphases for application in quasi-brittle materials
2022
Quasi-brittle materials mainly fail under shear or tensile stress state. When the stress limit is reached, fractures propagate and the stress-strain relation exhibits a softening branch until failure. In the framework of finite elements, discrete crack models and continuous smeared crack models have been implemented to best capture material’s response. In this ambit, we propose a strategy based on the Augmented Finite Element Method (A-FEM, [1]), which can be placed among the discrete crack models, since intra-element weak discontinuity is considered and modelled through a zero-thickness interphase model (IPH, [2, 3]). The original element is in practice divided in two elastic sub-elements …
A phase-field model for strain localization analysis in softening elastoplastic materials
2019
Abstract The present paper deals with the localization of strains in those structures consisting of materials exhibiting plastic softening response. It is assumed that strain localization develops in a finite thickness band separated from the remaining part of the structure by weak discontinuity surfaces. In view of the small thickness of the band with respect to the dimensions of the structure, the interphase concept is used for the mechanical modeling of the localization phenomenon. We propose a formulation for the quasi-static modeling of strain localization based on a phase-field approach. In this sense, the localization band is smeared over the volume of the structure and a smooth tran…