Modelling of concrete fracture at aggregate level using FEM and DEM based on X-ray μCT images of internal structure

Skarżyński, Łukasz; Nitka, Michał; Tejchman, J.

doi:10.1016/j.engfracmech.2015.08.010

Cited by 156 publications

(84 citation statements)

References 45 publications

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“…Force transmission bottlenecks, a subset of contacts that are prone to becoming overloaded beyond their capacity, can predict the location and pattern of the ultimate crack in the nascent stages of loading before damage initiates inside the specimen. The extent to which this data analytics technique can predict failure patterns in a range of multiphase concrete specimens and loading conditions (e.g., compression, 3-point bending tests [9,10]) will be reported in [11]. .…”

Section: Discussionmentioning

confidence: 99%

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Of cuts and cracks: data analytics on constrained graphs for early prediction of failure in cementitious materials

et al. 2017

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Abstract. Using data from discrete element simulations, we develop a data analytics approach using network flow theory to study force transmission and failure in a 'dog-bone' concrete specimen submitted to uniaxial tension. With this approach, we establish the extent to which the bottlenecks, i.e., a subset of contacts that impedes flow and are prone to becoming overloaded, can predict the location of the ultimate macro-crack. At the heart of this analysis is a capacity function that quantifies, in relative terms, the maximum force that can be transmitted through the different contacts or edges in the network. Here we set this function to be solely governed by the size of the contact area between the deformable spherical grains. During all the initial stages of the loading history, when no bonds are broken, we find the bottlenecks coincide consistently with, and therefore predict, the location of the crack that later forms in the failure regime after peak force. When bonds do start to break, they are spread throughout the specimen: in, near, and far from, the bottlenecks. In one stage leading up to peak force, bonds collectively break in the lower portion of the specimen, momentarily shifting the bottlenecks to this location. Just before and around peak force, however, the bottlenecks return to their original location and remain there until the macro-crack emerges right along the bottlenecks.

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Section: Discussionmentioning

confidence: 99%

“…This study is part of a broader effort to investigate force transmission and failure in bonded granular media [9,10]. In contrast to unbonded grains [5], force transmission pathways in brittle or quasi-brittle bonded granular materials remain essentially fixed prior to fracture.…”

Section: Introductionmentioning

confidence: 99%

Of cuts and cracks: data analytics on constrained graphs for early prediction of failure in cementitious materials

et al. 2017

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“…The advantage of the discrete meso-scale approach is that it is able to directly simulate a heterogeneous meso-structure of materials. Thus it may be used for a detailed study of mechanisms of the initiation, growth and propagation of both microcracks and discrete macro-cracks that greatly control the macroscopic concrete behaviour [14][15][16][17]. It may also be used for a better calibration of continuous models for concrete with respect to the e.g.…”

Section: Introductionmentioning

confidence: 99%

Meso-scale analyses of size effect in brittle materials using DEM

et al. 2018

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The paper describes numerical meso-scale results of a size effect on strength, brittleness and fracture in brittle materials like concrete. The discrete element method (DEM) was used to simulate the size effect during quasi-static splitting tension with the experimental-based meso-structure. The two-dimensional (2D) calculations were carried out on concrete cylindrical specimens with two diameters wherein two different failure modes occurred (quasi-brittle and very brittle with the snap-back instability). Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and macro-voids, based on x-ray micro-CT-images of the real concrete meso-structure. Attention was paid to the effect of the different specimen diameter on both the strength, brittleness and fracture pattern. Each internal energy component was analyzed in the fracture process zone and beyond it, and compared for the different post-peak behaviour of concrete. The evolutions of the number of broken contacts, coordination number, crack displacements and normal contact forces were also shown. Of specific interest was the fracture initiation and formation of two different failure modes. Next, the 2D DEM results of a size effect for 4 different specimen diameters were directly compared with corresponding experiments from the research literature. The experimental size effect was realistically reproduced in numerical calculations, i.e. the concrete strength and ductility decreased with increasing concrete specimen diameter. The calculated decreasing strength approached an asymptote with increasing cylindrical specimen diameter within the considered specimen size range.

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“…Interactions between particles require a force model that describes how the interactions occur, being important to determine the time interval between successive integrations since it is directly related to the simulation time accuracy. DEM has application in solving different problems involving particle behavior from different areas such as simulation of concrete failure (Skarzynski et al, 2015) and concrete flow (Remond & Pizette, 2014), failure propagation in rocks (Trivino & Mohanty, 2015) and study of soil movement (Asaf et al, 2007). This method is also used in studies of grain post-harvest (Lu et al, 1997;Sakaguchi & Favier, 2000;Raji & Favier, 2004;Coetzee & Lombard, 2013;Hou et al, 2014;Leblicq et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Deformation of Peaches Submitted to Cyclic Loading Using the Discrete Element Method

Pinto

Ferraz

2018

Eng. Agríc.

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This study aimed to use and validate a simple contact force model that describes the behavior of peaches stored in a wooden box, loaded cyclically, by using the discrete element method. The Kelvin-Voigt contact force model was used and the cyclic loading in the simulation was performed with an amplitude of 1 mm and frequency of 12 Hz for time intervals of 3600, 5400, and 7200 s. The laboratory test was performed with a peach box attached to a vibrating table by applying the same excitation conditions used in the simulation. For validation, model results were compared with those from the laboratory test by using deformation values of fruits in the contact regions. To measure this deformation, we adapted the methodology for determining the radius of curvature. The Kelvin-Voigt linear contact model, despite its simplicity in representing the viscoelastic behavior, adequately estimated the final deformation in peaches submitted to cyclic loading.

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Modelling of concrete fracture at aggregate level using FEM and DEM based on X-ray μCT images of internal structure

Cited by 156 publications

References 45 publications

Of cuts and cracks: data analytics on constrained graphs for early prediction of failure in cementitious materials

Of cuts and cracks: data analytics on constrained graphs for early prediction of failure in cementitious materials

Meso-scale analyses of size effect in brittle materials using DEM

Deformation of Peaches Submitted to Cyclic Loading Using the Discrete Element Method

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