Criteria for Elastic Fracture

Zehnder, Alan T.

doi:10.1007/978-94-007-2595-9_4

Cited by 8 publications

(10 citation statements)

References 17 publications

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“…5 we show the force F at the top plate and the fracture surface A generated as functions of the displacement u z . For crack formation of brittle materials it is known that the dissipated energy is proportional to the fracture surface [56]. We observe that there are initially few independent force peaks for small displacements for which the force drops to zero as the particles lose the contact with the top plate.…”

Section: Unconfined Breaking Of a Single Grainmentioning

confidence: 69%

Evolution of fragment size distributions from the crushing of granular materials

2019

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We study the fragment size distributions after crushing of single and many particles under uniaxial compression inside a cylindrical container by means of numerical simulations. Under the assumption that breaking goes through the bulk of the particle we obtain the size distributions of fragments for both cases after large displacements. For the single particle crushing, this fragmentation mechanism produces a log-normal size distribution, which deviates from the power-law distribution of fragment sizes for the packed bed. We show that as the breaking process evolves, a power-law dependency on the displacement is present for the single grain, while for the many grains system, the distribution converges to a steady state. We further investigate the force networks and the average coordination number as a function of the particle size, which gives inside about the origin of the power-law distributions for the granular assembly under uniaxial compression.

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Section: Unconfined Breaking Of a Single Grainmentioning

confidence: 69%

Evolution of fragment size distributions from the crushing of granular materials

2019

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“…To simulate the crack propagation, we need to apply a criterion for crack growth. We use the simple Griffith criterion [19] : When applied loading is such that…”

Section: Plane Strain Elasticitymentioning

confidence: 99%

Numerical simulation of acoustic emission during crack growth in 3-point bending test

Berezovski

2017

Struct Control Health Monit

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“…In general, the fracture toughness of most steels decrease with the lowering of the temperature. [22,23] For CNG system with leakage on the container wall, the temperature of leaking CNG gas will drop due to Joule-Thomson cooling effect when CNG gas passes through the crack, thus chilling the vessel wall in the vicinity of crack and reducing fracture toughness of the wall. This may push the transition of previously stable crack propagation to become critical leading to its rapid growth.…”

Section: Motivation Of the Workmentioning

confidence: 99%

“…For CNG systems, the temperature of the leaking CNG gas will drop due to the Joule-Thomson cooling effect when the gas passes through the crack, thus chilling the vessel wall in the vicinity of the crack and reducing fracture toughness of the localized metal. [22,23,31] This may push the transition of a previously stable crack propagation to become critical, leading to its rapid growth. Therefore, prior to applying LBF technology, it is necessary to evaluate the temperature drop of CNG gas leaking through a crack due to the Joule-Thomson (JT) cooling effect and then the temperature change of the vessel wall around a crack due to heat transfer, and the effect on the fracture toughness of the metal.…”

Section: Page 21mentioning

confidence: 99%

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Study of Joule-Thomson cooling effect due to leakage in compressed gas pressure vessels

Ai¹

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The reliability of pressure vessels in Compressed Natural Gas (CNG) ship is very important because there is very high pressure inside the CNG container (up to 250 bar). A key way to maintaining the integrity of pressure vessels is the principle of Leak-Before-Failure (LBF). However, the temperature of leaking CNG will drop due to Joule-Thomson cooling effect when CNG passes through the crack. The localized cooling effect on the steel plates may affect the ductile to brittle transition failure. Hitherto, the LBF is applied to piping system without considering the temperature change of steel material caused by Joule-Thomson cooling effect. Simulation and experiments thus are desirable to verify the effect in a narrow leaking crack on pressure vessel. By this means, the application of LBF may need to be corrected. The narrow leaking crack can be considered to comprise many short and equivalent parts along the through-wall direction. Each part can be considered as a small throttling type nozzle. An iterative calculation program in MATLAB has been developed in this thesis. Due to the similarity on Joule-Thomson effect, argon is chosen as a substitute for CNG with safety in mind. The program is developed to calculate the pressure, velocity, density, temperature, viscosity, thermal conductivity and heat transfer coefficient of leaking argon through the crack by considering the Joule-Thomson effect. The calculated results of temperature, pressure and heat transfer coefficient of argon along the crack depth are used as boundary conditions in COMSOL FEA program for the heat transfer and thermal stress simulation. In MATLAB iterative calculations, the initial argon pressure inside the pressure vessel is the maximum pressure of 91 bar during test. The initial temperature is room temperature of 30 o C. Solutions of pressure, velocity and density of leaking argon of each small space inside the crack are firstly obtained after inputting the crack dimensions and roughness parameters. The pressure of leaking Argon drops from 91 bar at the entrance of the crack to 9.5 bar at the exit of the crack. The velocity of leaking Argon through the crack does not change much. The density of leaking Argon drops from 150.7 kg/m 3 at the entrance of the crack to 16.8 kg/m 3 at the exit of the crack. Then the temperature of leaking argon inside the crack is calculated. The temperature of leaking Argon decreases from 30 o C at the entrance of the crack to 0.04 o C at the exit of the crack.

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Criteria for Elastic Fracture

Cited by 8 publications

References 17 publications

Evolution of fragment size distributions from the crushing of granular materials

Evolution of fragment size distributions from the crushing of granular materials

Numerical simulation of acoustic emission during crack growth in 3-point bending test

Study of Joule-Thomson cooling effect due to leakage in compressed gas pressure vessels

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