3D numerical modelling of bit‐rock fracture mechanisms in percussive drilling with a multiple‐button bit

Saksala, Timo

doi:10.1002/nag.2173

Cited by 11 publications

(21 citation statements)

References 24 publications

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“…Cho et al (2013) used a Finite Element Method (FEM)-code with a strain-rate dependent constitutive law to simulate the excavation process of two adjacent cutters in 3D. Saksala (2013) recently published the results of a FEM-simulation that investigates the dynamic process of percussive drilling in 3D. His results are in good agreement with the experimental work of Howarth and Bridge (1988b).…”

Section: Related Workmentioning

confidence: 72%

Rock Failure and Crack Propagation Beneath Disc Cutters

2014

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Analyses of rock failure mechanisms beneath disc cutters are presented. Full-scale cutting tests are conducted to assess the global energy input in comparison with rock chips and excavated volume. Small-scale cutting tests are subsequently used for macro-and microscopic analyses of rupture modes and crack propagation. A high spatial resolution allows to obtain pictures of crack networks in different rock types. It is shown that all specimens develop lateral cracks in sufficiently confined areas whereas median cracks typically develop in boundary regions. Regarding cutting forces, a hypothesis is proposed that associates sudden force drops accompanied by sudden sound emission with grain crushing in the proximity of the cutter tip.

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Section: Related Workmentioning

confidence: 72%

Rock Failure and Crack Propagation Beneath Disc Cutters

2014

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“…By accounting for the symmetric boundary conditions and the number of buttons per drill bit, the penetration stiffness, K s , value is 340 kN/mm. The values of penetration per impact and also the penetration stiffness K s obtained from the numerical simulations are in good agreement with real drilling results [10].…”

Section: Modeling Of Percussive Drillingmentioning

confidence: 99%

“…This work is performed under 2D plane strain conditions. More recently, the model was extended to deal with 3D simulations [10]. Chiang et al [11] modeled the impact of tool to the rock and rock fragmentation in a drilling process using a 3D finite element (FE) approach.…”

Section: Introductionmentioning

confidence: 99%

Granite rock fragmentation at percussive drilling – experimental and numerical investigation

Saadati

Forquin

Weddfelt

et al. 2013

Num Anal Meth Geomechanics

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International audienceThe aim of this study is to numerically model the fracture system at percussive drilling. Due to the complex behavior of rock materials, a continuum approach is employed relying upon a plasticity model with yield surface locus as a quadratic function of the mean pressure in the principal stress space coupled with an anisotropic damage model. In particular, Bohus granite rock is investigated and the material parameters are defined based on previous experiments. This includes different tests such as direct tension and compression, three point bending and quasi-oedometric tests to investigate the material behavior at both tension and confined compression stress states. The equation of motion is discretized using a FE approach and the explicit time integration method is employed. EOI (Edge-On Impact) tests are performed and the results are used to validate the numerical model. The percussive drilling problem is then modeled in 3D and the bit-rock interaction is considered using contact mechanics. The fracture mechanism in the rock and the bit penetration- resisting force response are realistically captured by the numerical model

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“…This work is performed under 2D plane strain conditions. More recently, the model was improved to deal with 3D simulations [13].…”

Section: Introductionmentioning

confidence: 99%

On the Mechanical Behavior of Granite Material With Particular Emphasis on the Influence From Pre-Existing Cracks and Defects

Saadati

Forquin

Weddfelt

et al. 2018

Journal of Testing and Evaluation

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In this investigation, experiments were carried out in order to determine the mechanical properties of Bohus granite considering the influence from pre-existing cracks and defects. The experimental investigation aimed at a complete material characterization, for the purpose of mechanical analyses using advanced constitutive models, based on a variety of tests. In doing so, direct tensile and compression tests were performed to evaluate the stiffness and strength; quasi-oedometric tests were carried out in order to obtain the deviatoric and volumetric behavior of the material at different levels of hydrostatic pressure (up to 860 MPa); three-point bend tests were performed to evaluate the quasi-static strength of the rock and its distribution. Weibull statistics was then employed to describe the strength distribution. The intact specimens indicated a rather low scatter in the mechanical properties such as Young’s modulus and tensile strength. However, specimens with large initial defects behaved differently. The failure mechanism in these specimens was not as brittle as the intact ones. The crack was opened on the tensile surface of such specimens during the three-point bend test at an early stage during loading, as demonstrated by digital image correlation results.

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3D numerical modelling of bit‐rock fracture mechanisms in percussive drilling with a multiple‐button bit

Cited by 11 publications

References 24 publications

Rock Failure and Crack Propagation Beneath Disc Cutters

Rock Failure and Crack Propagation Beneath Disc Cutters

Granite rock fragmentation at percussive drilling – experimental and numerical investigation

On the Mechanical Behavior of Granite Material With Particular Emphasis on the Influence From Pre-Existing Cracks and Defects

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