scholarly journals Experimental and Numerical Study on Mechanical Properties and Deformation Behavior of Beishan Granite considering Heterogeneity

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Z. H. Wang ◽  
Y. L. Tan ◽  
S. M. Li ◽  
T. Z. Wang ◽  
X. C. Wu
Keyword(s):  
Numerical Simulation ◽  
Mechanical Response ◽  
Numerical Study ◽  
Failure Process ◽  
Confining Pressure ◽  
Sample Volume ◽  
Mechanical Tests ◽  
Peak Strength ◽  
Research Subjects ◽  
Beishan Granite

Disposal of high-level radioactive waste (HLW) deep underground is one of the most challenging research subjects in rock engineering. In China, Beishan granite is usually chosen as host rock for the construction of the HLW repository. In this study, mechanical tests are conducted on Beishan granite and the stress-strain state during the complete failure process is analyzed by numerical simulation. The results show that the tensile strength and uniaxial compressive strength of Beishan granite are 8.66 and 162.9 MPa, respectively. Dilatancy appears when the stress reaches about 81% of the peak strength. Heterogeneity is introduced by Weibull distribution in numerical simulation. With the increase of homogenization degree, the degraded elements are more easily to concentrate locally. Based on experimental and numerical simulation results, it is noticeable that the sample volume is basically in the state of compaction before reaching the peak strength. The elements are more likely to show expansion, and the splitting failure dominates the destroy mode when the confining pressure is relatively low. With increasing confining pressure, more and more degraded elements are concentrated in the shear band, which develops from the surface to the interior of the sample during loading. Therefore, the granite shows ductile mechanical response characteristics when the confining pressure is relatively high. The results are instructive for the construction of the repository.

Numerical Study of Deformation and Fracture of Ceramics Nanocomposite with Different Structural Parameters under Mechanical Loading

2016 ◽  
Vol 683 ◽  
pp. 601-608
Author(s):  
Igor S. Konovalenko ◽  
Egor M. Vodopjyanov ◽  
Evgenii V. Shilko
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Numerical Study ◽  
Structural Parameters ◽  
Phenomenological Approach ◽  
Sample Volume ◽  
Model Composite ◽  
Deformation And Fracture ◽  
Kinetics Of ◽  
Geometrical Dimensions

Deformation, fracture and effective mechanical properties of sintered ceramics composite under uniaxial compression were studied. To perform this investigation the plain numerical model of ceramics composites based on oxides of zirconium and aluminum with different structural parameters was developed. The model construction was carried out within the frame of particle based method, namely the movable cellular automaton method (MCA). The implementation of the phase transition in the MCA-model composite was carried out on the basis of the phenomenological approach, the main point of which was the formulation of the principle of irreversible mechanical behavior of the material. Increase the fracture toughness of ceramics after (T-M) transition in its structure was realized in the model by introducing transition kinetics of the automata pair from "bound" to an "unbound" state. The structure of model composite was generated on the basis of scanning electron microscope images of micro-sections of real composite. The influence of such structural parameters as geometrical dimensions of layers, inclusions, and their spatial distribution in the sample, volume content of the composite components and their mechanical properties, as well as the amount of zirconium dioxide undergone the phase transformation on the mechanical response were investigated

Numerical Study of Elastic-Brittle Failure of Notched Openings in Rocks

2005 ◽  
Vol 297-300 ◽  
pp. 2605-2611
Author(s):  
Shan Yong Wang ◽  
S.K. Au ◽  
K.C. Lam ◽  
Chun An Tang
Keyword(s):  
Numerical Study ◽  
Progressive Failure ◽  
Process Analysis ◽  
Failure Process ◽  
Confining Pressure ◽  
Numerical Code ◽  
Tunnel Wall ◽  
Model Studies ◽  
Borehole Breakout ◽  
Rock Failure Process

Borehole breakout is the process by which portions of borehole or tunnel wall fracture or spall when subjected to compressive stresses. The stress-strain characteristics of rock during loading and unloading confining pressure are studied firstly. To overcome the difficulties in analytical model studies, a numerical code, RFPA2D (Rock Failure Process Analysis), developed by CRISR, Northeastern University, China, is used to investigate the progressive failure of breakout around tunnel. The heterogeneity of rock was also taken into account in the software. The numerical simulation reproduces the formation notch in rocks by the growth, interaction and coalescence of randomly distributed macrocracks. It is illustrated from the numerical simulated results that breakout direction of tunnel is parallel with the minor stress tensor in the plane perpendicular to the borehole axis. Specifically due to the inclusion of heterogeneity, some peculiarities are studied both in the evolution of fracture and the influence of borehole on the peak intensity of specimen as well as the AE event patterns.

Numerical Study on the Fracture Evolution around Cavities in Rock

2005 ◽  
Vol 297-300 ◽  
pp. 2598-2604
Author(s):  
Shan Yong Wang ◽  
S.K. Au ◽  
K.C. Lam ◽  
Chun An Tang
Keyword(s):  
Shear Fracture ◽  
Model Simulation ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Confining Pressure ◽  
Numerical Code ◽  
Tensile Fracture ◽  
Fracture Evolution ◽  
Rock Failure Process

By using numerical code RFPA2D (Rock Failure Process Analysis), the evolution of fracture around cavities subjected to uniaxial and polyaxial compression is examined through a series of model simulation. It is shown from the numerical results that the chain of events leading to the collapse of the cavity may involve all or some of the fractures designated as primary tensile, shear and remote fracture. Numerical simulated results reproduce the evolution of three types of fractures. Under the condition of no confining pressure, the tensile mode dominates with collapse coinciding with the sudden and explosive appearance of the secondary tensile fracture; at moderate higher confining pressure, the tensile mode is depressed, comparatively, the shear effect is strengthened. Nevertheless, tensile fractures especially in remote fractures stage still play a role; at higher pressure, the shear fracture dominates the remote fractures. In addition, the evolution and interact of fractures between multiple cavities is investigated, considering the stress redistribution and transference in compressive and tensile stress field.

scholarly journals Numerical simulation study on rheological failure characteristics of rock mass under high stress

2020 ◽  
Vol 192 ◽  
pp. 04003
Author(s):  
Liming Qiu ◽  
Xueqiu He ◽  
Dazhao Song ◽  
Zhenlei Li
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Failure Process ◽  
High Stress ◽  
Sudden Change ◽  
Confining Pressure ◽  
Simulation Software ◽  
The Body ◽  
Failure Characteristics ◽  
Rock Failure Process

This paper uses the RFPA numerical simulation software to establish a numerical model of the rheological failure of the rock mass under stress. Rheological failure characteristics of the body was researched, and the results shows: (1) The rupture sequence of rock rupture is from the corner to the middle. When the rock loses stability under pressure, the rock often ruptures from the corner. The corner gradually collapses and cracks. Then the cracks spread to the middle of the rock. Many cracks extending from the corners are in the rock. The central part intersects each other and eventually causes the rock to break. (2) Rock samples of different lithologies have different stress values when they break under the same confining pressure. From the experimental process, we know that granite>sandstone>mudstone. Therefore, the higher the strength of the rock, the harder the rock will be broken. (3) The weaker the plasticity at rupture, the stronger the brittleness and the stronger the sudden change of rupture. In the deep mining process, the greater the confining pressure, the more obvious the rheological characteristics of the rock, and the greater the total energy released during the rock failure process.

Meso-Level Numerical Study on Different Type of Fiber Reinforced Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 3730-3734
Author(s):  
Ya Fang Zhang ◽  
Hao Liu ◽  
Jiang Ping Chen
Keyword(s):  
Reinforced Concrete ◽  
Numerical Study ◽  
Failure Process ◽  
Temporal Distribution ◽  
Fiber Reinforced Concrete ◽  
Peak Strength ◽  
Fiber Reinforced ◽  
Meso Level ◽  
Failure Patterns ◽  
Complete Failure

To investigate failure mechanism and toughening features of fiber reinforced concrete (FRC) with different reinforced fibers, meso-level numerical simulations have been conducted on FRCs incorporated with steel, glass and polypropylene fibers, respectively (which were named as SFRC, PPRC and GRC). The complete failure process of crack initiation, coalescence and development, interaction and final break have been simulated. By analyzing the failure patterns of specimens, also the spatial and temporal distribution of acoustic emission and loading - step curves, it can be concluded that both peak strength and toughness of SFRC and GRC can be greatly improved. However, for PRC, the improvement of peak strength is little while its toughness can be enhanced significantly.

Numerical Simulation of Compressive Experiment for Rock with a Natural Interlayer

2012 ◽  
Vol 217-219 ◽  
pp. 1389-1392
Author(s):  
Feng Shan Han ◽  
Li Song
Keyword(s):  
Numerical Simulation ◽  
Compressive Strength ◽  
Process Analysis ◽  
Failure Process ◽  
Peak Load ◽  
Strain Curve ◽  
Confining Pressure ◽  
Physical Experiment ◽  
Stress Strain Curve ◽  
Rock Failure Process

It is difficulty to make physical experiment for compressive experiment of rock with a natural interlayer I Natural interlayer affect greatly on mechanical property of rock. In this paper, Rock Failure Process Analysis Code RFPA is used to simulate influence of natural interlayer to compressive strength of rock by numerical simulation under compression. Through numerical simulation complete stress strain curve and peak load can be obtained for compressive experiment of rock with a natural interlayer. RFPA can be effectively used to investigate anisotropy of compression for rock with natural interlayer under different confining pressure. Numerical simulation show that anisotropy of compressive strength of rock with a natural interlayer varies with inclination of natural interlayer, as the confining pressure increase, the compressive strength, the plasticity and ductility increase for rock with a natural interlayer. That provides new method to analyze and investigate mechanical behavior for multilayer composite material such as rock mass with a natural interlayer，finally Index of Anisotropy for rock with a natural interlayer are put forward

scholarly journals Experimental and Numerical Study on the Compressive Failure of Composite Laminates with Fiber Waviness Defects

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3204
Author(s):  
Yuequan Wang ◽  
Shuhua Zhu ◽  
Hongshuang Li ◽  
Long Zhou ◽  
Wentao Yi
Keyword(s):  
Numerical Simulation ◽  
Failure Load ◽  
Numerical Study ◽  
Experimental Testing ◽  
Failure Process ◽  
Experimental Results ◽  
Compressive Failure ◽  
Fiber Waviness ◽  
Acceptance Criterion ◽  
The Impact

Fiber waviness defects are found in the inner surface of the hat-shaped stringers manufactured by a process system. In order to establish the acceptance criterion for the stringers with the fiber waviness defects, experimental testing and numerical simulation were carried out in this study. Specially induced fiber waviness defects of four pre-defined severity levels were manufactured and tested. A maximum of a 58.1% drop in compressive failure load is observed for the most severe level in the experimental results. A finite element model with progressive damage method and cohesive zone technique was developed to simulate the failure process and the impact of fiber waviness defects. The numerical simulation results of compressive failure load have a good agreement with experimental results qualitatively and quantitatively. In addition, two simple parameters, i.e., aspect ratio A/H and the number of plies with fiber waviness, are proposed to characterize the influence of the fiber waviness on the compressive failure load for the purpose of fast engineering quality checks.

scholarly journals Stress wave propagation in different number of fissured rock mass based on nonlinear analysis

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiaoming Lou ◽  
Mingwu Sun ◽  
Jin Yu
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Confining Pressure ◽  
Displacement Discontinuity ◽  
Stress Wave Propagation ◽  
Theoretical Derivation ◽  
Mechanics Model ◽  
Fissured Rock ◽  
Deep Rock ◽  
Theoretical Accuracy

AbstractThe fissures are ubiquitous in deep rock masses, and they are prone to instability and failure under dynamic loads. In order to study the propagation attenuation of dynamic stress waves in rock mass with different number of fractures under confining pressure, nonlinear theoretical analysis, indoor model test and numerical simulation are used respectively. The theoretical derivation is based on displacement discontinuity method and nonlinear fissure mechanics model named BB model. Using ABAQUS software to establish a numerical model to verify theoretical accuracy, and indoor model tests were carried out too. The research shows that the stress attenuation coefficient decreases with the increase of the number of fissures. The numerical simulation results and experimental results are basically consistent with the theoretical values, which verifies the rationality of the propagation equation.

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

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