The Strength of Solids

Бартенев, Г. М.; Zuyev, Yu.S.

doi:10.1016/b978-0-08-003110-1.50005-4

Cited by 7 publications

(4 citation statements)

References 31 publications

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“…Let us consider a loaded crack with stress intensity coefficient K 1 in a brittle material. The expression for linear strain T can be obtained with integration of elastic energy density considering Irvine relations[33] for stress distribution near the crack tip: where α = 9/16 – coefficient obtained with integration, – crack tip radius estimated as considering that the material before a crack tip will be destroyed when the stress reaches 0.1E [34]. In equations (2) and (3) E and K 1C mean Young's modulus and fracture toughness respectively.…”

Section: Theoretical Descriptionmentioning

confidence: 99%

Fracture toughness in some hetero-modulus composite carbides: carbon inclusions and voids

Popov

Vishnyakov

2016

Advances in Applied Ceramics

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Structure and mechanical characteristics of dense ceramic composites synthesised by reactive hot pressing of TiC-B 4 C powder mixtures at 1800-1950°C under 30 MPa were investigated by Xray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM and EDX). The results show that during hot pressing solid-phase chemical reaction 2TiC + B 4 C = 2TiB 2 + 3C has occurred with final products like TiB 2 -TiC-C, TiB 2 -C or TiB 2 -B 4 C-C hetero-modulus composite formation with around one micrometer size carbon precipitates. The fracture toughness depends on the amount of graphite precipitation and has a distinct maximum K1C = 10 MPa m 1/2 at nearly 7 vol.-% of carbon precipitate. The fracture toughness behaviour is explained by the developed model of crack propagation. Within the model, it is shown that pores (voids) and low-modulus carbon inclusions blunt the cracks and can increase ceramic toughness in some cases. ARTICLE HISTORY

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Section: Theoretical Descriptionmentioning

confidence: 99%

Fracture toughness in some hetero-modulus composite carbides: carbon inclusions and voids

Popov

Vishnyakov

2016

Advances in Applied Ceramics

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“…Fatigue breakage is a result of the time dependence of the strength, and in this context the duration of action of the load is important [13][14][15].…”

Section: -mentioning

confidence: 99%

“…Then if the duration of the action of load on the the rock is dt, owing to the irreversibility of the deloading process, the relative decrease in life is dt/t(o), where t(o) is the life under the current value o of the stress. The gradual accumulation of damage during some time interval t b leads to complete breakage of the rock by loss of its cohesion [14,15]. Fatigue breakage of the cohesion bonds of the rock occurs when the sum of the damage is equal to unity, which is expressed mathematically in the form [16]:…”

Section: -mentioning

confidence: 99%

Analytical estimation of cyclic fracture of rocks during drilling

Mataev

Malachikhanov

1969

Soviet Mining Science

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The driving of various types of mine workings for commercial mineral production involves the process of rock breaking. Roller-bit drills are the instruments most used to break rocks [1][2][3].In the operation of a roller bit, breakage occurs after single or repeated cyclic action of the teeth on the rock. An urgent problem [4][5][6][7] is the influence of the cyclic loading parameters, especially the amplitude and frequency of the dynamic load components, on the process of rock breaking at the face.In this article we shall suggest a method for quantitative estimation of the influence of the cyclic loading parameters on the process of rock breaking by roller bits at the face of a vertical working, with allowance for the time dependence of the strength and the mining-geological and technical fractors. The problem can be formulated as follows. Suppose we have a vertical mine working with internal diameter D and depth L, filled to its mouth with unfiltered wash liquid, the parameters of which are given in [8,9]. We also know the mechanical properties and stress-strain state of the face rocks lying at depth L [10,11]. We are to determine the number of cycles N before the rock breaks owing to the action of the roller teeth under given axial load and rotation speed.If the angular velocity of the roller about its axis is w = 2nn/60 x D/d, then the frequency of reciprocatory motion of the body of the bit for synchronous roiling of the rollers from tooth to tooth over the face will be wz. The period of longitudinal vibration of the body of the bit will be 2n/wz, which corresponds to the time of rolling of the rollers from one tooth to the next, and represents the duration of contact during a single event of interaction of a tooth with the rock The number of cycles to breakage, N, and the duration of contact of a tooth of the roller with the rock, t c, are linked with the time to complete breakage as follows: d 2,-:During drilling, as the angular speed of the bit increases, so do the number of blows inflicted on the face rock by the roller teeth in unit time, the speed of impact, and the dynamic component of the load. This increases the efficiency of rock breaking and the mechanical rate of advance.After a large number of cycles of loading by the roller teeth, as damage to the rocks increases, so does the probability of breakage of the rocks at the face of the working increase. Fatigue breakage is a result of the time dependence of the strength, and in this context the duration of action of the load is important [13][14][15].The rule of summation of damage for the long-term strength for time-dependent stress is as follows [16]. If we divide up the variable stress into a series of values acting during successive small time intervals, we can neglect stress changes and regard the stress as constant in each interval. Then if the duration of the action of load on the the rock is dt, owing to the irreversibility of the deloading process, the relative decrease in life is dt/t(o), where V. I. Lenin Dagestan State University, Makhac...

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“…An energy barrier significance is associated with u o . In practice all the constants must be evaluated using experimental data as described by Zhurkov [10], Chiao [12], or Bartenev and Zuyev [13]. One notices that for a certain stress level, the exponential term in equation (4) The universal nature of equation (4) is not automatically assumed in the Western scientific community.…”

Section: Deformational Approaches To Delayed Failures (Creep Rupture)mentioning

confidence: 99%