Automatic Crack Propagation Tracking

Shephard, Mark S.; Yehia, Nabil A.B.; Burd, Gary S.; Weidner, Theodore J.

doi:10.1016/b978-0-08-032789-1.50027-6

Cited by 3 publications

(3 citation statements)

References 12 publications

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“…The prediction of crack growth for 3D models, under various modes of loading, has been made in many studies for a number of years 1–4 . In most of the above cases the prediction techniques were limited to crack growth within a small region of the model.…”

Section: Earlier Studies On Three‐dimensional Crack Growthmentioning

confidence: 99%

Experimental and numerical studies on dynamic crack growth in layered slate rock under wedge impact loads: part II – non‐plane strain problem

Alam

Munaswamy

Swamidas

2007

Fatigue Fract Eng Mat Struct

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A B S T R A C T Dynamic crack propagation in non-plane strain (or 3D) slate blocks under wedge impact loads was investigated numerically in this part of the paper. A parabolic-shaped crack trajectory was taken into consideration to model the crack propagation in slate blocks for analyzing the impact splitting of layered slate rock. Major and minor axes of the parabola were determined from the condition of equal mode I stress intensity factors (SIFs) along the crack front. Mode I SIFs were determined for experimental breaking loads for each increment of crack growth in a manner similar to that mentioned in part I of this paper. These values were compared with the plane strain material fracture toughness value obtained from experimental studies and very good agreement was obtained between them, for the case of actual load applied on the specimen. Numerical analysis of a field problem, i.e., separation of a large-sized slate slab from the rock strata in a slate quarry using wedge impacting, was also carried out in this paper. It can be observed that a large magnitude of load is required to break large-sized slate blocks; but this load is applied through a number of smaller load-capacity actuators-in-parallel, requiring large power capacity for the hydraulic pumps. However, this required power could be reduced considerably if the load applied on the line of hydraulic actuators is cascaded across the (line of) actuators (starting from centrally placed actuators) with a small time delay (equal to the initial crushing time in slate rock).These studies were motivated by the need to estimate theoretically the required in-plane impact loads for splitting layered slate rocks; in addition, the design of the necessary machinery/equipment to apply that load was also required in this study. The experimental testing of large-scale specimens will generally be beyond the reach of a researcher working in a medium-sized research laboratory. The other way to do the same is to verify and establish a numerical methodology from the results of small-scale experimental investigations and then to apply the same numerical procedure to compute the approximate breaking loads for large-sized slate blocks. From these computed breaking loads, the field equipment can be designed and fabricated.Two-dimensional and their equivalent plane strain (3D) finite-element analyses of the dynamic crack propagation of slate blocks, broken experimentally under plane strain conditions (transverse length of the block was equal to the transverse length of the wedge), were reported in part I of this paper. However, the prevalence of plane strain conditions for a rock breaking process is rather a rare event. Generally the loading area, or the extent of line load, would be much smaller than the length of the slate rock over which the failure of slate block is to be initiated. This leads to a 3D loading condition. Therefore, it is necessary to analyze large-sized slate blocks numerically as well. In part II of this paper, laboratory test results, and numerical analy...

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Section: Earlier Studies On Three‐dimensional Crack Growthmentioning

confidence: 99%

Experimental and numerical studies on dynamic crack growth in layered slate rock under wedge impact loads: part II – non‐plane strain problem

Alam

Munaswamy

Swamidas

2007

Fatigue Fract Eng Mat Struct

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“…For a long time, the FEM has been used to determine the SIF's for cracked media. Numerous researchers have employed this method to study fracture propagation processes (Shephard et al, 1985;Boone et al, 1987;Wawrzynek et al, 1988;Swenson and Ingraffea, 1988;Wei and De Bremaecker, 1994). The main disadvantage of the FEM in dealing with this problem is that the finite element mesh has to be updated following each step of crack extension.…”

Section: Introductionmentioning

confidence: 98%

Fracture propagation of anisotropic plates by the boundary element method

Chen

1999

Journal of the Chinese Institute of Engineers

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This paper presents a boundary element method combined with the maximum tensile stress criterion for predicting crack initiation angles and simulating fracture propagation paths in cracked anisotropic plates under mixed mode loading. Since the calculated displacements near the crack tip by the BEM have been verified to be very accurate, a decoupling technique can be used to determine the mixed mode stress intensity factors based on the definition of the J-integral and the relative displacements at the crack tip. Numerical examples are presented for the calculation of stress intensity factors for both isotropic and anisotropic cases. It can be found that our numerical results are in good agreement with those reported by previous authors. Fracture propagation in an anisotropic plate under mixed mode loading is simulated by an incremental crack extension with a piece-wise linear discretization. A computer program, which can automatically generate a new mesh (required for analyzing sequentially the boundary configuration) has been developed to simulate the fracture propagation process. It was found that the numerical analysis could predict relatively well the direction of crack initiation and the path of fracture propagation.

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“…The early methodology was based on separating the element edges during crack formation process [3], [4] and was later combined with adaptive re-meshing approaches [5], [6]. An alternative approach that was widely used in the 1980's was the concept of smeared cracking that incorporated some plasticity based strain-softening relations [7], [8].…”

Section: Introductionmentioning

confidence: 99%

Modeling of Fracture Propagation in Concrete Structures Using a Constitutive Relation with Embedded Discontinuity

Pietruszczak

Haghighat

2015

Studia Geotechnica Et Mechanica

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In this paper, the problem of modeling of mixed mode cracking in concrete structures is addressed within the context of a constitutive law with embedded discontinuity (CLED). This approach, which was originally developed for describing the propagation of localized deformation in a "smeared" sense, is enhanced here to model a discrete nature of crack propagation. The latter is achieved by coupling the CLED approach with the level-set method, which is commonly used within the framework of Extended Finite Element (XFEM). Numerical simulations of experimental tests conducted at Delft University, which involve four-point bending of a notched concrete beam under the action of two independent actuators, are presented. The results based on enhanced CLED approach are directly compared with XFEM simulations. The predictions from both these methodologies are quite consistent with the experimental data, thereby giving advantage to CLED scheme in view of its simplicity in the numerical implementation.

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Automatic Crack Propagation Tracking

Cited by 3 publications

References 12 publications

Experimental and numerical studies on dynamic crack growth in layered slate rock under wedge impact loads: part II – non‐plane strain problem

Experimental and numerical studies on dynamic crack growth in layered slate rock under wedge impact loads: part II – non‐plane strain problem

Fracture propagation of anisotropic plates by the boundary element method

Modeling of Fracture Propagation in Concrete Structures Using a Constitutive Relation with Embedded Discontinuity

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