Modeling of interfaces in two-dimensional problems using solid finite elements with high aspect ratio

Keywords: multi-scale cohesive models, computational homogenization, heterogeneous material failure, Embedded Finite Elements (EFEM). AbstractThe paper describes the computational aspects and numerical implementation of a two-scale cohesive surface methodology developed for analyzing fracture in heterogeneous materials with complex microstructures. This approach can be categorized as a semi-concurrent model using the Representative Volume Element (RVE) concept.A variational multi-scale formulation of the methodology has been previously presented by the authors. Subsequently, the formulation has been generalized and improved in two aspects: i) cohesive surfaces have been introduced at both scales of analysis, they are modeled with a strong discontinuity kinematics (new equations describing the insertion of the macro-scale strains, into the micro-scale and the posterior homogenization procedure have been considered); ii) the computational procedure and numerical implementation have been adapted for this formulation. The first point has been presented elsewhere, and it is summarized here. Instead, the main objective of this paper is to address a rather detailed presentation of the second point.Finite element techniques for modeling cohesive surfaces at both scales of analysis (FE 2 approach) are described: i) finite elements with embedded strong discontinuities (EFEM) are used for the macroscale simulation, and ii) continuum-type finite elements with high aspect ratios, mimicking cohesive surfaces, are adopted for simulating the failure mechanisms at the micro-scale.The methodology is validated through numerical simulation of a quasi-brittle concrete fracture problem. The proposed multi-scale model is capable of unveiling the mechanisms that lead from the material degradation phenomenon at the meso-structural level to the activation and propagation of cohesive surfaces at the structural scale.

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“…A similar technique for mono-scale analysis has been reported in Manzoli et al [49] and Oliver et al [31].…”

Section: Micro-scale Variational Equilibrium Problemmentioning

confidence: 97%

Cohesive surface model for fracture based on a two-scale formulation: computational implementation aspects

et al. 2016

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“…According to (6), the fiber stresses Σ f at the surface of the microcrack reduces the stress intensity factor, toughening the FRC composite.…”

Section: Microcrack Arrestmentioning

confidence: 99%

“…Degenerated 2D and 3D solid elements with almost zero thickness as proposed by [6,12] are used. The formulation is based upon the principles of the continuum strong discontinuity approach for the representation of cracks in finite elements, making use of the strong discontinuity kinematics in conjunction with degenerated finite elements.…”

Section: Frc Model At the Structural Levelmentioning

confidence: 99%

“…Recently, [6] introduced a modification of the classical zero-thickness interface elements by using degenerated solid finite elements with almost zero thickness. This technique can be easily implemented in standard FE programs using conventional solid elements and has been successfully used in capturing complex cracking processes in the structures made of plainas well as reinforced concrete, without the need of any crack tracking algorithm.…”

Section: Introductionmentioning

confidence: 99%

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Multiscale modeling FRC Composites

Timothy¹,

Zhan²,

Meschke

2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

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Abstract. We propose a multiscale model for FRC composites that is a combination of semianalytical and computational sub-models specified at multiple scales. At the scale of the single fiber, a semi-analytical model is developed that characterizes the microslip behavior at the interface between the matrix and the fiber in terms of the overall composite stresses. The influence of fiber bundles on microcrack bridging and arrest is taken into account within the framework of the linear elastic fracture mechanics. Upscaling to the macroscopic level is achieved by using continuum micromechanics. We show that the macroscopic deformation of the FRC composite is governed by a 'TERZHAGI' like effective stress. Selected numerical experiments provide insight into the role of the interface property, resulting on the macroscopic level -in a brittle, softening behaviour in case of weak bond and a rather ductile, hardening behavior in case of a relatively strong interface bond that is completely described by simple microslip laws. For the finite element analyses of failure behavior at the structural level, the so-called 'interface solid element' (ISE) is used to represent the cracking process. The softening behavior of ISE is governed by the crack bridging law obtained above. The implicit-explicit integration scheme is implemented to enhance the robustness of computation. Selected numerical examples demonstrate that the crack pattern as well as the structural responses under tension-dominant stress conditions can be well simulated 1 INTRODUCTION

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“…To represent the bond-slip behavior between the steel bars and concrete, a constitutive damage model consistent with the Continuous Strong Discontinuity Approach (CSDA) is adopted, as proposed by Manzoli et al (2012). This model is formulated on the effective stress field associated with a scalar damage variable,…”

Section: J2 Continuum Damage Model For Steel-concrete Interfacementioning

confidence: 99%

Failure behavior modeling of slender reinforced concrete columns subjected to eccentric load

Rodrigues

Manzoli

Bitencourt

et al. 2015

Lat. Am. j. solids struct.

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This work presents a numerical model to simulate the failure behavior of slender reinforced concrete columns subjected to eccentric compression loads. Due to the significant influence of the lateral displacements on the loading state provided by an eccentric load, geometric nonlinearity is considered. The responses of the concrete in tension and compression are described by two scalar damage variables that reduce, respectively, the positive and negative effective stress tensors, which lead to two different damage surfaces that control the dimension of the elastic domain. To describe the behavior of the reinforcements, truss finite elements with elastoplastic material model are employed. Interaction between the steel bars and concrete is modeled through the use of interface finite elements with high aspect ratio and a damage model designed to describe the bond-slip behavior. The results showed that the numerical model is able to represent the nonlinear behavior of slender concrete columns with good accuracy, taking into account: formation of cracks; steel yielding; crushing of the concrete in the compressive region; and interaction between rebars and concrete. KeywordsReinforced concrete columns: nonlinear analysis; continuum damage model; interface finite element.Failure behavior modeling of slender reinforced concrete columns subjected to eccentric load INTRODUCTIONDue to the important role played by reinforced concrete (RC) columns as structural elements, there are a number of papers available in the literature investigating their behavior. In most cases, the variables investigated are the slenderness ratio, concrete strength, steel ratio, boundary conditions, type of cross-section, concrete shrinkage and creep, and eccentricity loading (Kim and Yang, 1995;Claeson and Gylltoft, 1998;Diniz and Frangopol, 2003;Elwood, 2004;Majewski et al., 2008;Pallarés et al., 2008;Leite et al., 2013;Carmona et al., 2013;Bouchaboub and Samai, 2013 After the advent of the high strength concrete (HSC) a large number of slender RC columns has been constructed, and more researchers have given special attention to this subject (Pallarés et al., 2008;Kim and Yang, 1995). Consequently, the development of numerical tools to support the analyses has increased and different numerical models to simulate the failure mechanism have been proposed. For instance, in order to investigate the behavior of RC columns under eccentric compression load, with consideration of cracks, Majewski et al. (2008) proposed an approach based on elasto-plasticity with non-local softening model. Recently, Carmona et al. (2013) developed a fracture mechanics model to describe the buckling behavior of lightly concrete columns, wherein the structural response is a result of the propagation of one single crack at the column's central region. Using the finite difference method, Bouchaboub and Samai (2013) proposed an approach to simulate the behavior of slender high strength RC columns under combined biaxial and axial compression. For all the aforementioned...

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Modeling of interfaces in two-dimensional problems using solid finite elements with high aspect ratio

Cited by 73 publications

References 17 publications

Cohesive surface model for fracture based on a two-scale formulation: computational implementation aspects

Cohesive surface model for fracture based on a two-scale formulation: computational implementation aspects

Multiscale modeling FRC Composites

Failure behavior modeling of slender reinforced concrete columns subjected to eccentric load

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