Creep and stress relaxation in the vicinity of a micropore under the conditions of hydrostatic loading and unloading

Bazhin, A. A.; Murashkin, E. V.

doi:10.1134/s1028335812080095

Cited by 9 publications

(9 citation statements)

References 1 publication

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“…is involved several cycles of unloading and loading at the maximum stress value for various stages of steady-state creep, followed by the proposal of a simple mathematical model to describe the test result. Bazhin and Murashkin [6] studied the phenomenon of loading and unloading creep deformation, as well as the stress relaxation characteristics of micropore areas of the material under the condition of hydrostatic pressure. Based on the research, it was possible to establish the nonlinear rheological model, which describes the material's loading and unloading plastic deformation and creep deformation.…”

Section: Introductionmentioning

confidence: 99%

Unloading Rheological Test and Model Research of Hard Rock under Complex Conditions

Zhang

Yang

2020

Advances in Materials Science and Engineering

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In order to study the unloading rheological properties of hard rock under complicated conditions, the proposed Mengdigou hydropower station with a granite dam foundation was taken as the research object. This paper studied the unloading rheological properties of the granite by testing means, and it obtained the unloading rheological deformation characteristics and deformation rules of the granite under complex stress conditions. The granite unloading rheological characteristics of the whole stress-strain curve were analyzed, and the nonlinear unloading rheological model (FOD-HKVP) was proposed based on the fractional-order derivative. When certain conditions are satisfied, it is possible to degrade this model into the classical Nishihara model, but it should be noted that the FOD-HKVP model is a more reasonable way to determine the long-term strength of the granite and to consider also the rock unloading rheological damage effect. It introduced the fractional-order viscous body of combination components with a different fractional-order derivative to describe the nonlinear creep characteristics of the granite unloading, which provides an adequate description of steady-state creep and accelerated creep properties. Following the analysis of test data and parameter identification for the FOD-HKVP model, the rationality of the model was validated. Compared with the Nishihara model, the fitting accuracy of FOD-HKVP model was more accurate.

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Section: Introductionmentioning

confidence: 99%

Unloading Rheological Test and Model Research of Hard Rock under Complex Conditions

Zhang

Yang

2020

Advances in Materials Science and Engineering

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“…Fahimifar et al [17] modified a viscoplastic model to account for the creep deformation of rocks associated with the wide range of stress levels and implemented the model in numerical finite difference code (FLAC). Bazhin and Murashkin [18] studied the creep deformation and the stress relaxation characteristics of the material with loading and unloading condition under hydrostatic pressure and established a nonlinear rheological model.…”

Section: Introductionmentioning

confidence: 99%

The Research on the Effect of Humidity on the Rheological Model of Swelling Rock

Zhang

2020

Advances in Civil Engineering

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The research on the rheological mechanical behaviour of swelling rock in the condition of humidity field has a significant meaning for large rock engineering, such as deep coal mining, tunnelling, and slope engineering. Based on the Nishihara model, considering on the effect of humidity factor on swelling rock, the rheological elements are established and the effects of humidity on the damage of rock, the viscosity, and the elasticity are introduced. Moreover, the viscoelastic plasticity constitutive equations are established under the coupling of swelling rock stress and humidity. Afterward, considering the effects of humidity on the damage, elasticity, and viscosity, the creeping, unloading, and relaxation equations have been deduced. From this research, under the state of low stress σ3P<σS, the Nishihara model which considers the effect of humidity shows the properties of stable creeping. In addition, the unloading curves contain instantaneous elasticity, elastic after effect, and the viscosity flow induced by the humidity. However, under the state of high stress σ3P≥σS, it is an unstable creeping model. The unloading curves include instantaneous elasticity, elastic after effect, and the viscosity flow induced by the stress and the humidity. This model reflects the rheological properties of swelling rock comprehensively, and it can be used for rock rheological analysis.

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“…The presented mathematical model of large elastocreep deformations is based on equations (1), (4), (5), (7), (11). One can use the presented approach for mechanical design creep fabricated parts from creep-elastic materials determining the strength and the shape of final products.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…Throughout the paper we use mathematical model of the finite elastocreep deformations (see details in [11]). The kinematic equation for parts of the Almansi total strain d ij can be written in the Cartesian system (Eulerian coordinates) in the form…”

Section: Constitutive Equationmentioning

confidence: 99%

On Finite Strains in Continua with Complex Rheology

Murashkin

Klindukhov

2017

J. Phys.: Conf. Ser.

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Abstract. The present study deals with the multiphysics modelling frameworks for the elasticcreep-plastic material. The proposed theory of large deformations is based on the classical formalism of nonequilibrium thermodynamics. Reversible and irreversible components of total deformations are derived by the constitutive differential equations. The development of this theory involves statements and solutions of the correct boundary value problems. The problem of deformation of the material in the vicinity of microdefect was considered. Resulting integrodifferential equations system was derived. Preliminary RemarksModern additive manufacturing technology [1,2] states the problem of creating and developing of new mathematical models of growth and deformation of structural materials. The calculation of stress-strain state parameters is needed during the forming processes of material [3]. In the design of ship hulls and aircraft are widely used panels and profiles of hardly-deformed aluminum alloys [4]. Traditional methods of formation of such structural elements often leads to the appearance of the plastic breaks, cracks and other damages. Thus, the effective way of this fabrication is metal forming under creep and low strain rates. These processes ensures the production of construction with high accuracy, which reduces the complexity of assembly and welding, and increase the residual life and the quality of construction.The mathematical description of the processes of thermomechanical treatment of contracture materials is faced with the necessity to consider the elastic properties of materials at all stages of the producing and utilization. Consideration of the problems in the classical models of small deformations is impossible when the relative shape of the body is strongly changed. Such problem is the process of deformation metals in vicinity of micropore under the intense pressure action. In this case, we are faced to assumption of large strains. Well known experiments [3,4] when the long-term strength of metal products after their treatment under hydrostatic pressure is significantly increased. Attempts to simulate such process of the micropores "healing" in the metal have been made repeatedly [4][5][6][7][8][9][10][11][12][13][14]. In [5] such problems are considered due to the model of large elastic-plastic deformation. In this case, the effect of adaptability to periodic loading on the cycle "loading and unloading" was shown in [6].

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Creep and stress relaxation in the vicinity of a micropore under the conditions of hydrostatic loading and unloading

Cited by 9 publications

References 1 publication

Unloading Rheological Test and Model Research of Hard Rock under Complex Conditions

Unloading Rheological Test and Model Research of Hard Rock under Complex Conditions

The Research on the Effect of Humidity on the Rheological Model of Swelling Rock

On Finite Strains in Continua with Complex Rheology

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