Effect of Intermetallic β-Mg17Al12 on Fracture of Ultralight Magnesium Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.535-536.160 ◽

2013 ◽

Vol 535-536 ◽

pp. 160-163

Author(s):

Ying Chun Guan ◽

Wei Zhou

Keyword(s):

Magnesium Alloy ◽

Intermetallic Compounds ◽

Fracture Propagation ◽

Fracture Initiation ◽

Tensile Loading ◽

Az91d Magnesium Alloy ◽

Initiation And Propagation ◽

Microcrack Propagation ◽

Plastic Zones

An AZ91D magnesium alloy was tested in either compression or tension, and extensive observation of the tested samples was carefully carried out to understand the fracture initiation and propagation processes. Cracking of β-Mg17Al12 intermetallic compounds was found to occur easily in plastic zones under either compressive or tensile loading. However, the cracking did not necessarily result in fracture propagation. It is argued that the fracture is controlled by the microcrack propagation.

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Full Fluid–Solid Cohesive Finite-Element Model to Simulate Near Wellbore Fractures

Journal of Energy Resources Technology ◽

10.1115/1.4028251 ◽

2014 ◽

Vol 137 (1) ◽

Cited By ~ 22

Author(s):

Saeed Salehi ◽

Runar Nygaard

Keyword(s):

Finite Element ◽

Hoop Stress ◽

Fracture Propagation ◽

Fracture Initiation ◽

Element Model ◽

Cohesive Elements ◽

Element Simulation ◽

Initiation And Propagation ◽

Fracture Sealing ◽

Wellbore Strengthening

This paper presents finite-element simulation for hydraulic fracture's initiation, propagation, and sealing in the near wellbore region. A full fluid solid coupling module is developed by using pore pressure cohesive elements. The main objective of this study is to investigate the hypothesis of wellbore hoop stress increase by fracture sealing. Anisotropic stress state has been used with assignment of individual criteria for fracture initiation and propagation. Our results demonstrate that fracture sealing in “wellbore strengthening” cannot increase the wellbore hoop stress beyond its upper limit when no fractures exist. However, this will help to restore part or all of the wellbore hoop stress lost during fracture propagation.

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Towards a field test for fracture propagation propensity in weak snowpack layers

Journal of Glaciology ◽

10.3189/172756506781828962 ◽

2006 ◽

Vol 52 (176) ◽

pp. 164-168 ◽

Cited By ~ 18

Author(s):

Dave Gauthier ◽

Bruce Jamieson

Keyword(s):

Field Test ◽

Fracture Propagation ◽

Field Tests ◽

Fracture Initiation ◽

Bimodal Distribution ◽

Test Method ◽

Flexural Wave ◽

Weak Layer ◽

Columbia Mountains ◽

Initiation And Propagation

AbstractSlab avalanche release requires fracture initiation and propagation in a weak snowpack layer. While field tests of weak-layer strength are useful for fracture initiation, the challenge remains to find a verified field test for fracture propagation. We introduce the two current versions of a field test for fracture propagation propensity, and report results of testing conducted in the Columbia Mountains of British Columbia, Canada, during the winter of 2005. By extending the column of a stability test approximately 3 m in the downslope direction, the test method allows for the development of a flexural wave in the slab, and thereby maintains the contribution of this wave and the associated weak-layer collapse to the fracture process. Fracture lengths collected on a day and location where the propagation propensity of the snowpack was locally high show a bimodal distribution, with approximately 50% of observed fractures similar to those collected in stable snowpacks, and approximately 50% with much longer fracture lengths.

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Model of Fracture Propagation in Hydraulic Isolation of the Wellbore

Vestnik NSU Series Information Technologies ◽

10.25205/1818-7900-2020-18-1-36-49 ◽

2020 ◽

Vol 18 (1) ◽

pp. 36-49

Author(s):

V. N. Lapin

Keyword(s):

Propagation Velocity ◽

Numerical Experiments ◽

Fracture Propagation ◽

Fracture Initiation ◽

Reservoir Pressure ◽

Initiation And Propagation ◽

The Stability ◽

Prestressed State ◽

Cement Plug

A model of fracture initiation and propagation along the boundary of a cement plug and a steel casing in a plugged wellbore is proposed. The model allows predicting the conditions of hydraulic isolation failure of a cement plug induced by reservoir pressure. The model describes the stress state of the cement and it’s breakaway from the steel casing caused by the pressure of the pore fluid flowing into the fracture. Numerical experiments show that the fracture propagation velocity and the stability of the hydraulic isolation are sensitive to the reservoir pressure and to the prestressed state of the cement. It is shown also that the quality of cement adhesion to steel and the size of the initial cementing defects have little effect on the initiation conditions and fracture propagation velocity.

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Numerical simulation on the effect of pore pressure gradient on the rules of hydraulic fracture propagation

Energy Exploration & Exploitation ◽

10.1177/01445987211009389 ◽

2021 ◽

pp. 014459872110093

Author(s):

Weiyong Lu ◽

Changchun He

Keyword(s):

Pressure Gradient ◽

Pore Pressure ◽

Hydraulic Fracture ◽

Fracture Propagation ◽

Fracture Initiation ◽

Hydraulic Fractures ◽

Initiation And Propagation ◽

Hydraulic Fracture Propagation ◽

Pore Pressure Gradient ◽

Stress Damage

To clarify the influence of pore pressure gradient on hydraulic fracture propagation, the stress distribution in and around the borehole is explained by theoretical analysis method in this paper. A mechanical model of hydraulic fracture initiation under the action of pore pressure gradient is established. Then coupled seepage-stress-damage software is used to simulate the initiation and propagation of hydraulic fractures in rock samples under the action of pore pressure gradient. Finally, the influence of the number and spatial position of the induction holes on the initiation and propagation of hydraulic fractures is analyzed. It is shown that: (1) Pore pressure gradient can effectively reduce the initiation pressure of hydraulic fractures. (2) The greater the pore pressure gradient is, the easier the hydraulic fracture is to spread to the region with high pore pressure. (3) With the action of pore pressure gradient, the hydraulic fracture is shaped as ‘丨’, ‘丿’ and ‘S’ types and can be represented by the four abstract conceptual models.

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