Phase-field regularized cohesive zone model (CZM) and size effect of concrete

Published on Jun 15, 2018in Engineering Fracture Mechanics4.406
路 DOI :10.1016/J.ENGFRACMECH.2018.04.038
De-Cheng Feng20
Estimated H-index: 20
(Ministry of Education),
Jian-Ying Wu23
Estimated H-index: 23
(SCUT: South China University of Technology)
Sources
Abstract
Abstract A phase-field regularized cohesive zone model (CZM) was recently proposed for both brittle fracture and cohesive failure within the framework of the unified phase-field damage theory. Motivated from the fact that this model gives length scale and mesh independent global responses for problems with or without elastic singularities, we further apply it in this work against the size and boundary effects of concrete under both mode-I and mixed-mode failure. More specifically, for the two independent experimental campaigns of three-point bending notched and unnotched concrete beams under mode-I failure, the quality of data-fitting is, at least, comparable to the best results reported in the literature. For another series of eccentrically notched concrete beam tests, the size effect with transition from mode-I fracture to mixed-mode failure is also predicted. In all numerical examples, not only the peak loads but also the softening regimes agree well with the experimental results using a single set of material parameters for a specific series of tests. Being accompanied with other merits, e.g., generic softening laws, no lateral widening, no need of extrinsic crack tracking nor the penalty stiffness, etc., the presented phase-field regularized CZM can be used as a promising approach in the modeling of damage and failure in solids and structures.
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#1Jian-Ying Wu (SCUT: South China University of Technology)H-Index: 23
Abstract Aiming to bridge the gap between damage and fracture mechanics for modeling localized failure in solids, this paper addresses a novel geometrically regularized gradient-damage model with energetic equivalence for cracking evolution. With the free energy potential defined as usual in terms of the local strain and damage fields, the constitutive relations are derived consistently from the standard framework of thermodynamics. Upon the sharp crack topology geometrically regularized by the ...
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Size and shape effects are important issues in predicting the global response of concrete structures. Small-scale tests performed in laboratory to determine the material properties are not enough to simulate large-scale structures. Many models are used to extrapolate small scale results to large scale simulations, but only few are able to recover size and shape effects. Recently a model of graded damage (TLS) has been proposed and comparison with cohesive zone models shows that this new model co...
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#1Jian-Ying Wu (SCUT: South China University of Technology)H-Index: 23
Abstract Being one of the most promising candidates for the modeling of localized failure in solids, so far the phase-field method has been applied only to brittle fracture with very few exceptions. In this work, a unified phase-field theory for the mechanics of damage and quasi-brittle failure is proposed within the framework of thermodynamics. Specifically, the crack phase-field and its gradient are introduced to regularize the sharp crack topology in a purely geometric context. The energy dis...
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The influence of the averaging operator of nonlocal continuum damage models near specimen boundaries on the size effect on strength of quasibrittle materials is investigated. Two phenomenological approaches, namely standard rescaling and distance-based models, are considered. The numerical results are compared to data from three-point bending tests of notched and unnotched beams recently reported in the literature. It is shown that both approaches can reproduce the experiments well for one type ...
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