Numerical Study of the Rock Fragmentation by Three TBM Cutters

2012 ◽  
Vol 594-597 ◽  
pp. 3-7
Author(s):  
Yan Wang ◽  
Zheng Zhao Liang
Keyword(s):  
Numerical Study ◽  
Rock Breaking ◽  
Rock Fragmentation ◽  
Numerical Code ◽  
Time Interval ◽  
The Finite Element Method ◽  
Whole Process ◽  
Disc Cutters ◽  
Initiation And Propagation ◽  
Damage Theory

Based on the mesoscopic damage theory and the finite element method, a numerical code RFPA was applied to investigate the rock fragmentation by three TBM cutters loaded one after another in different time interval. The whole process of crack initiation and propagation was successfully simulated by the cutters loaded with different step intervals. The time interval of the disc cutters has significant influence on the fracture patterns and the rock breaking efficiency. The simulated results show that there are three types of breakage mode of the rock subjected to compression by the cutters.

Numerical Simulation of Rock Fragmentation Process Induced by Two Disc Cutters

2011 ◽  
Vol 366 ◽  
pp. 224-228 ◽  
Author(s):  
Lin Tao Man ◽  
Shou Ju Li
Keyword(s):  
Rock Breaking ◽  
Rock Fragmentation ◽  
Fragmentation Process ◽  
The Finite Element Method ◽  
Penetration Process ◽  
Disc Cutters ◽  
Adjacent Disc ◽  
Realistic Description ◽  
Cutter Spacing ◽  
Fragmentation Processes

Rock fragmentation processes induced by two cutters were simulated by ABAQUS software with different cutter spacing. A series of numerical experiments reproduce the progressive process of rock fragmentation in indentation. The influence of different cutter spacing on the penetration process can also be clearly researched. Rock fragmentation process induced by two TBM disc cutters was performed using the finite element method. The simulation not only provided a realistic description of the rock fragmentation mechanism, but also supported the sufficient proof for the cutter spacing optimization between adjacent disc cutters for a given penetration depth. When the penetration is 6 mm, the cutter spacing optimization is 48 mm. The result shows that the numerical simulations will contribute to an improved knowledge of rock fragmentation in indentation and will be useful for performance assessment of TBM, which will enhance the efficiency of rock breaking.

scholarly journals The Effects of Confining Stress on Rock Fragmentation by TBM Disc Cutters

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
S. F. Zhai ◽  
S. H. Cao ◽  
M. Gao ◽  
Y. Feng
Keyword(s):  
Confining Pressure ◽  
Numerical Results ◽  
Rock Fragmentation ◽  
Disc Cutter ◽  
Confining Stress ◽  
Disc Cutters ◽  
Initiation And Propagation ◽  
Maximum Angle ◽  
Indentation Tests ◽  
Crushed Zone

In this paper, General Particle Dynamics (GPD3D) is developed to simulate rock fragmentation by TBM disc cutters under different confining stress. The processes of rock fragmentation without confining pressure by one disc cutter and two disc cutters are investigated using GPD3D. The crushed zone, initiation and propagation of cracks, and the chipping of rocks obtained from the proposed method are in good agreement with those obtained from the previous experimental and numerical results. The effects of different confining pressure on rock fragmentation are investigated using GPD3D. It is found that the crack initiation forces significantly increase as the confining stress increases, while the maximum angle of cracks decreases as the confining stress increases. The numerical results obtained from the proposed method agree well with those in previous indentation tests. Moreover, the effects of equivalent confining stress on rock fragmentation are studied using GPD3D, and it is found that rock fragmentation becomes easier when the equivalent confining stress is equal to 15MPa.

Numerical Study of Crack Propagation in Stiff Clays

2006 ◽  
Vol 324-325 ◽  
pp. 201-204
Author(s):  
Shan Yong Wang ◽  
K.C. Lam ◽  
Ivan W.H. Fung ◽  
Wan Cheng Zhu ◽  
Tao Xu ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Numerical Method ◽  
Numerical Study ◽  
Propagation Direction ◽  
Shear Stresses ◽  
Stiff Clays ◽  
Whole Process ◽  
Initiation And Propagation ◽  
Normal And Shear Stresses ◽  
Natural Slopes

Many stiff clays forming part of natural slopes and earth dams exist in the fissured state. When these cracks are subjected to gravity induced normal and shear stresses they may propagate. The present discussion presents a numerical method to study the propagation direction of cracks under stress fields similar to those found in the field. Not only did the results on one crack propagation direction obtained from the numerical method and the analytical results agree well, but numerical results have been used to investigate the mechanisms of the whole process of two horizontal cracks initiation and propagation and coalescence in stiff soils.

Numerical Study on Process of Breaking Rock with TBM Cutter in Different Cutting Orders

2010 ◽  
Vol 34-35 ◽  
pp. 1583-1586
Author(s):  
Ji Qiu Tan ◽  
Qing Tan ◽  
Yi Min Xia ◽  
Zi Jun Xu ◽  
Xi Long Qu
Keyword(s):  
Numerical Study ◽  
Simulation Models ◽  
Rock Breaking ◽  
Whole Process ◽  
Stress Contour ◽  
Breaking Mechanism ◽  
Rock Chip ◽  
Loading Modes ◽  
Tbm Cutter ◽  
Future Work

In order to research the effect of different cutting orders on breaking mechanism of TBM cutters for the rock without joints, this paper established the simulation models of breaking rock three TBM cutters in simultaneous and sequential orders, which is based on the 2D discrete element method. A series of numerical experiments were designed and the whole process of production and propagation of crack and rock breaking was successfully simulated. The simulation results showed that the cutter order determines the breaking mode, which is carefully analyzed: The chipping stress under the sequential order is higher than simultaneous way. The chips are formed by the side cracks under the two loading modes, while the shape of the rock chip are different. The distribution of the principal stress contour is almost symmetrical in different cutting order. Finally, conclusions and future work are summarized.

Study on Concrete Temperature Crack Based on Mesomechanics

2012 ◽  
Vol 212-213 ◽  
pp. 895-898
Author(s):  
Xing Hong Liu ◽  
Jing Ping Zhu ◽  
Xiao Lin Chang ◽  
Wei Zhou
Keyword(s):  
Brittle Damage ◽  
Whole Process ◽  
Concrete Crack ◽  
Initiation And Propagation ◽  
Three Phase ◽  
Temperature Load ◽  
Damage Theory ◽  
Point Bend ◽  
Complete Process ◽  
Temperature Crack

A three-phase mesomechanics model was established to simulate the aggregate, cement mortar and the interface between them. In order to reflect the meso characters and heterogeneity of concrete, the parameters were randomly valued on the Weibull distribution. Then, by using this model the complete process of concrete crack propagation was analyzed based on the elastic brittle damage theory. This method was verified by simulation of uniaxial tension and three-point bend beam test. Finally, concrete structure cracking at early age during a cold snap was simulated under different surface insulation conditions. The results show that this method can simulate the crack initiation and propagation effectively and reflect the whole process of concrete crack under temperature load.

On the Effect of Pad Clearance and Preload Manufacturing Tolerances on Tilting Pad Bearings Rotordynamic Coefficients

2013 ◽  
Author(s):  
Jose L. Gomez ◽  
Saira Pineda ◽  
Sergio E. Diaz
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Numerical Code ◽  
Perturbation Approach ◽  
The Finite Element Method ◽  
Rotordynamic Coefficients ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Manufacturing Tolerances ◽  
Tilting Pad Bearings

Tilting pad bearings (TPB) are commonly used in high-speed and high-power turbomachines, due to its contributions in avoiding rotor instabilities. Studies related to the estimation of dynamic coefficients have been carried out considering a uniform value of the geometric parameters (clearance, pre-load) for all bearing pads. These assumptions give a reasonable agreement on the direct coefficients prediction while, recently, some discrepancies have been found on the cross-coupled coefficients. In this work, a numerical study is devised to analyze the influence of the pre-load and clearance variations from pad to pad, due to manufacturing tolerances, on the dynamic coefficients prediction. The numerical code for the estimation of the dynamic coefficients uses the finite element method to integrate the Reynolds’s equation through a perturbation approach. Variations on the pre-load and clearance for each bearing’s pad were performed, producing plots quantifying the sensitivity of the tilting pad bearing cross coupled coefficients to manufacturing tolerances.

Research on the Optimal Disc Cutter Spacing for Rock-Breaking Based on ANSYS

2014 ◽  
Vol 664 ◽  
pp. 143-147
Author(s):  
Yan Li ◽  
Ke Zhang ◽  
Jian Sun ◽  
Hong Sun ◽  
Zi Nan Wang
Keyword(s):  
Finite Element ◽  
Rock Breaking ◽  
Rock Fragmentation ◽  
Cutting Process ◽  
Disc Cutter ◽  
Rock Stress ◽  
Fragmentation Efficiency ◽  
Finite Element Software ◽  
Disc Cutters ◽  
Cutter Spacing

Objective: To study the influence of disc cutter spacing on rock fragmentation efficiency and optimize cutter layout and improve the efficiency of disc cutter. Method: ANSYS, a finite element software was used to simulate double disc cutter cutting process. Result: Find a good corresponding relationship between penetration and cutter spacing. At the process of sandstone, if disc cutter spacing as 54 ~ 55 mm, rock crushing as the largest and rock fragmentation efficiency is the highest; with the penetration of 10 mm. If disc cutter spacing as 66~68.5mm, rock crushing as the largest and rock fragmentation efficiency is the highest with the penetration of 15 mm. Changing the cutter spacing and penetration, rock stress and broken degree will also change. Conclusion: Double disc cutters change within the range of best cutter spacing, cutter spacing is proportional to the rock crushing. If the cutter distance is greater than the best cutter spacing, the ledge will be appeared. For one type of rocks, the penetration would have some effects on the optimal cutter spacing. If the penetration increases, the optimal cutter spacing increases gradually, at the time of other construction parameters unchanged.

scholarly journals A 3DEC Numerical Analysis of the Interaction Between an Uneven Rock Surface and Shotcrete Lining

2021 ◽  
Author(s):  
Ping Zhang ◽  
Ering Nordlund
Keyword(s):  
Numerical Study ◽  
Support Effect ◽  
Influential Factors ◽  
Numerical Analyses ◽  
Numerical Code ◽  
Rock Surface ◽  
Stress Concentrations ◽  
Circular Tunnel ◽  
Rock Tunnels ◽  
Shotcrete Lining

AbstractRock tunnels excavated using drilling and blasting technique in jointed rock masses often have a very uneven and rough excavation surface. Experience from previous studies shows that the unevenness of a rock surface has a large impact on the support effect of shotcrete lining. However, clear conclusions regarding the effect of 2D and 3D uneven surfaces were not obtained due to limited studies in the literature. The numerical analyses reported in this paper were made to investigate the influence of the surface unevenness of a circular tunnel opening on the support effect of shotcrete using a 3D numerical code (3DEC). The models were first calibrated with the help of observations and measured data obtained from physical model tests. The influential factors were investigated further in this numerical study after calibration had been achieved. The numerical analyses show that, in general, the unevenness of a tunnel surface produces negative support effects due to stress concentrations in recesses (compressive) and at apexes (tensile) after excavation. However, shotcrete sprayed on a doubly waved uneven surface has better support effect compared to shotcrete sprayed on a simply waved tunnel surface. The development of shear strength (specifically frictional strength) on the uneven interface between the shotcrete and the rock contributes to this effect, in the condition where bonding of the shotcrete does not work effectively. The interface is a crucial element when the interaction between the rock and shotcrete is to be simulated. When an entire tunnel surface is covered by shotcrete with high modulus, more failures will occur in the shotcrete especially when rock surface is uneven. Based on the numerical model cases examined, some recommendations on how to incorporate tunnel surface conditions (2D or 3D unevenness) in the design of a shotcrete lining are given.

Numerical Study of the Flow Forming Process of AISI 630 Stainless Steel

2011 ◽  
Vol 264-265 ◽  
pp. 24-29 ◽  
Author(s):  
Seyed Mohammad Ebrahimi ◽  
Seyed Ali Asghar Akbari Mousavi ◽  
Mostafa Soltan Bayazidi ◽  
Mohammad Mastoori
Keyword(s):  
Feeding Rate ◽  
Surface Defects ◽  
Numerical Study ◽  
Internal Diameter ◽  
The Finite Element Method ◽  
Forming Process ◽  
Flow Forming ◽  
Cold Forming ◽  
External Variables ◽  
Experimental Process

Flow forming is one of the cold forming process which is used for hollow symmetrical shapes. In this paper, the forward flow forming process is simulated using the finite element method and its results are compared with the experimental process. The variation of thickness of the sample is examined by the ultrasonic tests for the five locations of the tubes. To simulate the process, the ABAQUS explicit is used. The effects of flow forming variables such as the angle of rollers and rate of feeding of rollers, on the external variables such as internal diameter, thickness of tube and roller forces are considered. The study showed that the roller force and surface defects were reduced with low feeding rate and low rollers attack angles. Moreover, the sample internal diameter increased at low feeding rate and low rollers attack angles. The optimum variables for flow forming process were also obtained.

scholarly journals Modeling of Size Effects in Bending of Perforated Cosserat Plates

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Roman Kvasov ◽  
Lev Steinberg
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Numerical Study ◽  
The Finite Element Method ◽  
Classical Elasticity ◽  
Element Analysis ◽  
Plate Deformation ◽  
The Finite Element Analysis ◽  
Circular Holes ◽  
Different Shapes

This paper presents the numerical study of Cosserat elastic plate deformation based on the parametric theory of Cosserat plates, recently developed by the authors. The numerical results are obtained using the Finite Element Method used to solve the parametric system of 9 kinematic equations. We discuss the existence and uniqueness of the weak solution and the convergence of the proposed FEM. The Finite Element analysis of clamped Cosserat plates of different shapes under different loads is provided. We present the numerical validation of the proposed FEM by estimating the order of convergence, when comparing the main kinematic variables with an analytical solution. We also consider the numerical analysis of plates with circular holes. We show that the stress concentration factor around the hole is less than the classical value, and smaller holes exhibit less stress concentration as would be expected on the basis of the classical elasticity.

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