scholarly journals Elastic-Viscoplastic Constitutive Model of Soil under Cyclic Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yuan Ma ◽  
Hua Liang ◽  
Yongxue You ◽  
Weiguang Zhang ◽  
Limin Guo ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Yield Criterion ◽  
Case Analysis ◽  
Research Field ◽  
Constant Amplitude ◽  
Bingham Model ◽  
Viscoplastic Model ◽  
Flow Criterion

The creep problems are often involved in soil under cyclic loading, and its behaviors of soil under cyclic loading sparks many arguments in current research field. To propose one new model to demonstrate these creep behaviors of soil under cyclic loading, the cyclic loading was simplified equivalently, and the elastic-viscoplastic model (EVPM) for soil under cyclic loading was established based on the Bingham model. The yield criterion for soil under cyclic loading with constant amplitude was proposed following the simplified load. A constitutive equation based on the EVPM was constructed by using the flow criterion related to the yield criterion. Meanwhile, the parameters of EVPM were identified and discussed. In addition, the case analysis of the EVPM was also performed. The results indicate that the stable and destructive creep behaviors of soil under cyclic loading could be well described by the recommended EVPM, and the obtained parameters in the model exhibited a clear regularity with the increase of dynamic stress amplitude. Besides, the established model could be selected to predict the stable and destructive creep behavior of soil under cyclic loading.

The Deformation Characteristics of Soft Clay under Cyclic Loading

2012 ◽  
Vol 446-449 ◽  
pp. 1709-1712 ◽  
Author(s):  
Yong Zhang ◽  
Li Wan ◽  
Xiong Wei Li
Keyword(s):  
Elastic Modulus ◽  
Cyclic Loading ◽  
Elastic Strain ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Soft Clay ◽  
Dynamic Elastic Modulus ◽  
Deformation Characteristics ◽  
Cycle Number ◽  
Critical Type

Through the undrained dynamic triaxial experiment, the deformation characteristics of saturated soft clay under cyclic loading are investigated. The cyclic loading was simplified as sine wave. It is found that under different dynamic stress, the deformation patterns of specimen in this experiment can be divided into three kinds, such as dense compressed, tensile break-up and shear failure type. In the process of vibration, the deformation forms of samples can also be divided into three types by dynamic stress amplitude, such as stable, destructive and critical type. The dynamic stress amplitude corresponding to the critical type is called critical dynamic stress. With the dynamic elastic strain increasing gradually, the dynamic elastic modulus decreases and rigidity softening occurs. Furthermore, dynamic elastic modulus and dynamic elastic strain curve decrease while the cyclic number is increasing. Finally, to establish the equation of the relationship between dynamic elastic modulus and dynamic elastic strain, the factor of cycle number should be considered.

scholarly journals Experimental Study on Acoustic Emission and Resistivity Response of Sandstone under Constant Amplitude Cyclic Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Kui Wang ◽  
Xue Li ◽  
Zheng Huang ◽  
Mingjie Zhao
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Cyclic Load ◽  
Stress Amplitude ◽  
Rate Of Change ◽  
Rapid Decline ◽  
Engineering Practice ◽  
Loading Frequency ◽  
Constant Amplitude ◽  
Ae Signal

A lot of engineering practice shows that, during the construction and operation of rock mass projects, in addition to the static load, the rock is more subjected to cyclic load. Constant amplitude cyclic load is one of the simpler cyclic loading methods. The damage of rocks gradually accumulates under the action of periodic cyclic load, and finally, fatigue damage occurs, which affects the stability of the project. Therefore, it is necessary to study the mechanical properties of the rock under the action of constant amplitude cyclic load. Acoustic emission (AE) parameters and resistivity are both sensitive to the damage process of the rock and can well describe the damage evolution law of the rock. Under the action of constant amplitude cyclic loading, different loading conditions, different state specimens, and so on, factors will make a big difference to the AE signal and resistivity, such as the difference in stress amplitude, loading rate, and saturation. Therefore, in this paper, the typical sandstone in the Chongqing area is taken as the research object, the AE characteristics and resistivity characteristics of sandstone under different test conditions such as different stress amplitude, different loading frequency, and different saturation are tested, and the evolution of AE is found. It also has a three-stage rule: in the initial stage, the deformation is faster and the AE signal is strong; in the constant velocity stage, the deformation develops slowly and the AE signal is also stable; in the acceleration stage, the deformation develops sharply and the AE signal also becomes more intense. With the increase of cyclic loading stress amplitude, or the decrease of cyclic loading frequency, or the decrease of rock sample saturation, the acoustic emission signal generated in each cycle will be stronger. The resistivity as a whole shows a rapid decline in the loading phase and a rapid rebound in the unloading phase. The changes in resistivity at different stress amplitudes show differences in the first few cycles; the overall change trend of resistivity at different frequencies is consistent, but the rate of change increases with decreasing frequency, and the variation trend of resistivity is very different under different saturation.

scholarly journals Undrained Dynamic Behavior of Reinforced Subgrade under Long-Term Cyclic Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Min Geng ◽  
Debin Wang ◽  
Peiyong Li
Keyword(s):  
Elastic Modulus ◽  
Cyclic Loading ◽  
Dynamic Behavior ◽  
Vibration Frequency ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Confining Pressure ◽  
Reinforced Soil ◽  
Dynamic Elastic Modulus

To study the dynamic behavior of reinforced subgrade, a series of undrained cyclic triaxial tests of reinforced soil (the specimen a height of 50 cm and a diameter of 20 cm) were performed in this paper. The specimens were tested by varying confining pressure, vibration frequency, dynamic stress amplitudes, and reinforced layers. Orthogonal experiment is a better way to optimize the process of experiment. Impact on dynamic behavior of the reinforced soil specimens is discussed through orthogonal design of experiments in four factors and three levels. This study has demonstrated that the order of dynamic elastic modulus of reinforced soil is influenced by dynamic stress amplitude, frequency, reinforced layer, and confining pressure within changing in factor level. The dynamic stress amplitude has great influence on the dynamic elastic modulus of reinforced soil. The bearing capacity and dynamic elastic modulus of reinforced subgrade decrease slightly with the increase of dynamic strain. Frequency has an influence on the dynamic elastic modulus. It is shown that the cumulative strain of reinforced soil is related to the vibration frequency. The test results also exemplify the reinforced subgrade restrict lateral displacement of subgrade and reduce settlement of subgrade under long-term cyclic loading.

scholarly journals Visco-Elastoplastic Constitutive Fatigue Model for Rocks

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jianhao Liu ◽  
Shaoyun Pu ◽  
Junying Rao
Keyword(s):  
Steady State ◽  
Cyclic Loading ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Fatigue Properties ◽  
Test Results ◽  
One Dimensional ◽  
Fatigue Model ◽  
Flow Criterion ◽  
Important Significance

The study on the constitutive fatigue model for rocks under cyclic loading has an important significance in rock engineering. In order to study the fatigue properties of rocks under cyclic loading, according to the theory of rheological mechanics and the existing three basic one-dimensional fatigue elements, i.e., elastic, viscous, and plastic fatigue elements, the three-dimensional elastic, viscous, and plastic fatigue elements were constructed. Meanwhile, a fatigue yield criterion for rocks under cyclic loading was proposed, and a three-dimensional nonlinear visco-elastoplastic fatigue constitutive model (NVPFM) for rocks was established by using the flow criterion related to the proposed fatigue yield criterion. Compared with the test results of rocks under cyclic loading, the three-dimensional NVPFM could be used to describe the transient, steady-state, and tertiary creep phases of rocks under cyclic loading.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

scholarly journals Damage and fractal evolution trends of sandstones under constant-amplitude and tiered cyclic loading and unloading based on acoustic emission

2019 ◽  
Vol 15 (7) ◽  
pp. 155014771986102
Author(s):  
Dongxu Liang ◽  
Nong Zhang ◽  
Lixiang Xie ◽  
Guangming Zhao ◽  
Deyu Qian
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Damage Evolution ◽  
Damage Accumulation ◽  
Fractal Dimensions ◽  
Damage Variable ◽  
Constant Amplitude ◽  
Kaiser Effect ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading

It is of significance to study the damage and destruction of rock under cyclic loading in geotechnical engineering. We determined the trends in damage evolution of sandstone under constant-amplitude and tiered cyclic loading and unloading under uniaxial compression. The results of the study show that (1) the variation of acoustic-emission events was consistent with the stress curves and 89% of all acoustic-emission events occurred during the cycling stages. The observed Kaiser effect was more notable in tiered cycling. (2) The damage variable increased sharply in the cycling stages and its increment was 0.07 higher for tiered cycling than constant-amplitude cycling. Sandstone exhibited greater damage under tiered cyclic loading and unloading. (3) Equations for the evolution of the damage variable under the two cycle modes were obtained by fitting of experimental data. (4) The fractal dimensions of the constant-amplitude cycle were larger than those of the tiered cycle. The process of damage and destruction presents a trend of reducing fractal dimension. The damage accumulation of sandstone under tiered cycling was faster than under constant-amplitude cycling. These results provide references for damage and early warning of rock under both constant-amplitude and tiered cyclic loading and unloading.

scholarly journals Effects of Constant Amplitude Cyclic Loading on the Nonuniform Deformation of Sandstone Specimens

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Xiao-Bin Yang ◽  
Xin-Xing Han ◽  
Xiao-Yao Wang ◽  
Zi-Peng Zhang
Keyword(s):  
Cyclic Loading ◽  
Stress Condition ◽  
Mechanical Response ◽  
Correlation Method ◽  
Image Correlation ◽  
Constant Amplitude ◽  
Nonuniform Deformation ◽  
Evolution Stage ◽  
Number Of Cycles ◽  
Cyclic Loading Tests

In order to explore the mechanical response mechanism of rock materials under cyclic loading, uniaxial constant amplitude cyclic loading tests for sandstone specimens were carried out. The images of specimen deformation during the tests were captured by charge-coupled device (CCD) cameras. Based on the digital image correlation method (DICM), the evolution laws of nonuniform deformation and displacements around localization bands during cyclic loading were investigated. The experimental results show that, during the cyclic loading process, the nonuniform deformation continually escalates with the number of cycles increasing and fluctuates with the cyclic loading stress condition; the nonuniform deformation lags behind the variation of loading stress; and the whole nonuniform deformation experiences a slow evolution stage and a fast evolution stage. At the loading stage or unloading stage, the nonuniform deformation of rock deteriorates with the number of cycles increasing under the same stress condition. In each loading cycle, the nonuniform deformation at the unloading stage is more than that at the loading stage under the same stress condition. The time of dislocation displacements and tension displacements meets hysteresis, compared with the time of stress change. In addition, the dislocation displacements and tension displacements around localization bands in general increase with the number of cycles increasing. The displacement evolution around localization bands has the same hysteresis and accumulation laws as that of nonuniform deformation.

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