scholarly journals Nonlinear Viscoelastic-Plastic Creep Model of Rock Based on Fractional Calculus

2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Erjian Wei ◽  
Bin Hu ◽  
Jing Li ◽  
Kai Cui ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Fractional Calculus ◽  
Fractional Order ◽  
Engineering Application ◽  
Creep Model ◽  
Nonlinear Viscoelastic ◽  
Rock Creep ◽  
Order Change ◽  
Creep Constitutive Model ◽  
Plastic Creep

A rock creep constitutive model is the core content of rock rheological mechanics theory and is of great significance for studying the long-term stability of engineering. Most of the creep models constructed in previous studies have complex types and many parameters. Based on fractional calculus theory, this paper explores the creep curve characteristics of the creep elements with the fractional order change, constructs a nonlinear viscoelastic-plastic creep model of rock based on fractional calculus, and deduces the creep constitutive equation. By using a user-defined function fitting tool of the Origin software and the Levenberg–Marquardt optimization algorithm, the creep test data are fitted and compared. The fitting curve is in good agreement with the experimental data, which shows the rationality and applicability of the proposed nonlinear viscoelastic-plastic creep model. Through sensitivity analysis of the fractional order β2 and viscoelastic coefficient ξ2, the influence of these creep parameters on rock creep is clarified. The research results show that the nonlinear viscoelastic-plastic creep model of rock based on fractional calculus constructed in this paper can well describe the creep characteristics of rock, and this model has certain theoretical significance and engineering application value for long-term engineering stability research.

scholarly journals Nonlinear Viscoelastic–Plastic Creep Model Based on Coal Multistage Creep Tests and Experimental Validation

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3468 ◽  
Author(s):  
Junxiang Zhang ◽  
Bo Li ◽  
Conghui Zhang ◽  
Peng Li
Keyword(s):  
Creep Behavior ◽  
Physical Property ◽  
Creep Model ◽  
Creep Process ◽  
Creep Tests ◽  
Model Based ◽  
Nonlinear Viscoelastic ◽  
Improved Model ◽  
And Control ◽  
Plastic Creep

The development of fractures, which determine the complexity of coal creep characteristics, is the main physical property of coal relative to other rocks. This study conducted a series of multistage creep tests to investigate the creep behavior of coal under different stress levels. A negative elastic modulus and a non-Newtonian component were introduced into the classical Nishihara model based on the theoretical analysis of the experimental results to propose a nonlinear viscoelastic–plastic creep model for describing the non-decay creep behavior of coal. The validity of the model was verified by experimental data. The results show that this improved model can preferably exhibit decelerating, steady state, and accelerating creep behavior during the non-decay creep process. The fitting accuracy of the improved model was significantly higher than that of the classical Nishihara model. Given that acceleration creep is a critical stage in predicting the instability and failure of coal, its successful description using this improved model is crucial for the prevention and control of coal dynamic disasters.

Variable Parameters-Based Damage Creep Model of Weak Rock Layer and its Engineering Application

2014 ◽  
Vol 607 ◽  
pp. 835-838
Author(s):  
Wen Dong Yang ◽  
Jin Ping Chen ◽  
Feng Sun ◽  
Yan Mei Zhang
Keyword(s):  
Engineering Application ◽  
Creep Model ◽  
Dam Foundation ◽  
Weak Layer ◽  
Long Term Stability ◽  
Deterioration Effect ◽  
Loading Tests ◽  
Generalized Kelvin Model ◽  
Rock Parameters

In order to study the deformation mechanism of the weak layer in diabase dikes under long-term loading at a hydropower dam foundation, in situ plate loading tests were performed. A damage creep model which improved the five-parameter generalized Kelvin model was established to describe the creep behavior of the weak layer. In this model, the deterioration effect of the rock parameters is considered and the creep parameters of the rock deteriorate gradually. This model is applied in a slope design for a dam foundation at a hydropower station. Long-term stability of the slope after excavation is evaluated. It shows that when damage creep is considered, the displacement is larger compared with the case of ignoring damage creep. The study shows that the deterioration effect of the rock parameters is of full importance for the project design and construction safety.

A New Creep Constitutive Model for Eutectic Solder Alloy

2002 ◽  
Vol 124 (2) ◽  
pp. 85-90 ◽  
Author(s):  
X. Q. Shi ◽  
Z. P. Wang ◽  
W. Zhou ◽  
H. L. J. Pang ◽  
Q. J. Yang
Keyword(s):  
Constitutive Model ◽  
Testing Temperature ◽  
Creep Model ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Creep Flow ◽  
Reliability Of Solder Joints ◽  
Power Law Creep ◽  
Creep Constitutive Model

In this study, a large number of creep tests were carried out to study the effect of stress level and testing temperature on the creep behavior of 63 Sn/37Pb solder in a systematic manner. Based on the dislocation controlled creep mechanism and Gibbs’ free-energy theory, a new creep constitutive model was proposed. The model was found to describe accurately the creep flow of the solder and to be capable of explaining the issues of stress and temperature dependent stress exponent and activation energy in the Arrhenius power-law creep model. Furthermore, the model was employed to predict accurately the long-term reliability of solder joints in a PBGA assembly.

Study on Improved Nonlinear Viscoelastic-Plastic Creep Model Based on the Nishihara Model

2020 ◽  
Vol 38 (3) ◽  
pp. 3203-3214
Author(s):  
Mingyuan Yu ◽  
Baoguo Liu ◽  
Jinglai Sun ◽  
Wenlin Feng ◽  
Qi Wang
Keyword(s):  
Creep Model ◽  
Model Based ◽  
Nonlinear Viscoelastic ◽  
Plastic Creep

The Rock Creep Evaluation in the Analysis System for the Long-Term Behavior of TRU Waste Disposal System

2009 ◽  
Author(s):  
Shintaro Ohno ◽  
Seiji Morikawa ◽  
Morihiro Mihara
Keyword(s):  
Mechanical Behavior ◽  
Waste Disposal ◽  
Creep Model ◽  
Elastic Behavior ◽  
Elastic Model ◽  
Barrier Materials ◽  
Rock Creep ◽  
Cement Based Materials ◽  
Analysis System

MACBECE (Mechanical Analysis system considering Chemical transitions of BEntonite-based and CEment-based materials) is an analysis system to evaluate the long term mechanical behavior in the TRU (TRans Uranium) waste disposal system. TRU wastes are low level radioactive wastes that include long-lived nuclides. MACBECE is the system to calculate mechanical and chemical behavior in the near field including engineered barriers in the TRU waste disposal system, and subsequently to evaluate the hydraulic property in various components. MACBECE can evaluate the mechanical/ hydraulic alterations of two types of barrier materials, cement-based and bentonite-based materials. These materials, in the long-term, may be altered internally by chemical reaction. To evaluate the long-term mechanical behavior due to the chemical transitions, the nonlinear elastic model for the cement-based materials and the elasto-viscoplastic model for the bentonite-based materials were applied, based on the data from various laboratory tests. Also, proposed models based on the data from permeability tests were applied to evaluate the alteration of hydraulic conductivity. So as to realize the high reliable evaluation, the variable-compliance-type constitutive model proposed by Okubo (1992) was newly adopted for the rock creep evaluation in MACBECE. This creep model can express analytically nonlinear visco-elastic behavior and the over-peak-strength state behavior. This paper focuses on the adoptability of rock creep model in MACBECE. Applicability of the rock creep model is verified by conducting the numerical simulations with the long-term mechanical interaction between the TRU waste disposal system and the host rock.

scholarly journals A fractional order viscoelastic-plastic creep model for coal sample considering initial damage accumulation

2021 ◽  
Vol 60 (4) ◽  
pp. 3921-3930
Author(s):  
Peng Huang ◽  
Jixiong Zhang ◽  
Ntigurirwa Jean Damascene ◽  
Chaowei Dong ◽  
Zhaojun Wang
Keyword(s):  
Fractional Order ◽  
Coal Sample ◽  
Damage Accumulation ◽  
Creep Model ◽  
Initial Damage ◽  
Plastic Creep

Evaluation of Time-Independent and Time-Dependent Strains of Lead-Free Solder by Stepped Ramp Loading Test

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Ken-ichi Ohguchi ◽  
Katsuhiko Sasaki ◽  
Setsuo Aso
Keyword(s):  
Time Dependent ◽  
Lead Free ◽  
Creep Model ◽  
Basic Material ◽  
Loading Test ◽  
Material Constants ◽  
Instantaneous Strain ◽  
Free Solder ◽  
Creep Constitutive Model ◽  
Plastic Creep

This paper proposes a method to estimate basic material constants in an elasto-plastic-creep constitutive model for lead-free solders by conducting only a tensile test. The test employs a stepped ramp wave loading, which repeats instantaneous strain and strain maintenance. Time-independent strains are obtained from the stress-strain relations at the instantaneously strained parts, while the time-dependent strains are obtained from the stress-time relations during the strain maintaining periods. Based on the obtained time-independent and time-dependent strains, the values of the material constants in the elasto-plastic-creep model proposed by the authors are determined. Simulations of the viscoplastic deformations of a Sn–3.0Ag–0.5Cu solder alloy are also conducted to verify the validity of the proposed method.

scholarly journals Creep Behaviours of Argillaceous Sandstone: An Experimental and Modelling Study

2020 ◽  
Vol 10 (21) ◽  
pp. 7602
Author(s):  
Huaiguo Zheng ◽  
Qingxiang Cai ◽  
Wei Zhou ◽  
Xiang Lu ◽  
Ming Li ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Creep Model ◽  
Nonlinear Creep ◽  
Underground Excavations ◽  
Creep Theory ◽  
Term Stability ◽  
Long Term Stability ◽  
Rock Creep ◽  
Confining Pressures

Understanding the creep behaviours of rocks is essential for the long-term stability of underground excavations in mining engineering. Creep behaviours are more important when the mining depth is greater, which leads to the emergence of weak rock masses and high in situ stresses. In this study, the creep behaviours of argillaceous sandstone (AS) were systematically investigated. For the experimental investigation, creep tests were conducted on AS with different confining pressures (3, 6, 9, 12, 15, and 18 MPa) using an MTS815.02 rock mechanics test system. The mechanical characteristics of AS were analysed. For the numerical study, a nonlinear creep model of AS under equal and different confining pressures was established based on rock creep theory and plastic theory. The results showed that confining pressure could effectively improve the creep failure strength of AS, accelerating its creep deformation rate and process and reducing the final expansion volume. The nonlinear creep model was embedded in the FLAC3D software, and the experimental and numerical results agreed well. The experimental investigation and proposed creep model can provide important guidance in underground mines for safe long-term stability of underground excavations.

scholarly journals The 3D Nonstationary Creep Constitutive Model of Sandstone Based on Fractional Order

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Shuguang Zhang ◽  
Wenbo Liu
Keyword(s):  
Fractional Order ◽  
Creep Test ◽  
Creep Model ◽  
Good Prediction ◽  
Test Machine ◽  
Nonlinear Creep ◽  
Creep Characteristics ◽  
Marquardt Algorithm ◽  
Rock Creep ◽  
Triaxial Creep

Based on nonlinear creep characteristics of rock, triaxial creep tests were conducted on sandstone by using an MTS812.02 test machine. The creep properties of rocks under different conditions were analyzed. Establishing a creep model that describes parameter degradation is necessary to address the deterioration of rock creep parameters over time. A nonstationary Abel pot was constructed on the basis of laws of damage accumulation and deterioration. Then, the nonstationary creep model was established according to fractional order theory. The parameters of the triaxial creep test curve under different confining pressures were identified on the basis of Levenberg–Marquardt algorithm in Hengda coal mine in Fuxin, China. By comparing the model curve with the experimental curve, we found that the nonlinear model not only accurately reflected the creep characteristics of the decay and steady creep stages but also overcame the limitation of traditional creep model, that is, difficulty in describing the accelerated creep. Finally, the influence of fractional order and nonstationary parameters on rock creep was obtained by parameter sensitivity analysis. Overall, the model had high fitting degree as well as good prediction and analysis for 3D creep test data.

scholarly journals A Time-Dependent Creep Constitutive Model of Deep Surrounding Rock under Temperature-Stress Coupling

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaofeng Li ◽  
Zhixiang Yin
Keyword(s):  
Creep Deformation ◽  
Test System ◽  
Surrounding Rock ◽  
Creep Model ◽  
Spring Element ◽  
Rock Creep ◽  
Accelerated Creep ◽  
Different Temperatures ◽  
Creep Constitutive Model ◽  
Triaxial Creep Test

In order to study the creep behavior of the surrounding rock of Hengda coal mine in Fuxin under different temperatures, the triaxial creep test of sandstone is carried out by the MTS815.02 test system. The relationship between damage variables and temperature is constructed based on the Weibull distribution of the meso-probability voxel intensity. Aiming at the nonlinear characteristics of rock creep, a nonlinear viscous pot element and a nonlinear spring element are proposed. The two linear viscous pot elements and one linear spring element in the Nishihara model can be replaced separately. Thus, an unsteady parameter creep model is established. The comparison between the Nishihara model curve and the model and the experimental curves in this article has been added to the article. Furthermore, the superiority of this model can be proved. The results show that the established variable-time aging creep model not only can describe the rock attenuation creep and stable creep deformation characteristics but also can make up for the shortcomings of the traditional creep model that cannot describe the accelerated creep characteristics. Moreover, it predicts the development law of creep deformation well. The model is in good agreement with the test curve, which shows the correctness and rationality of the model. It has guiding significance for actual engineering support and prediction of long-term deformation of surrounding rock.

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