Research to the Influence of Bolt Direction on the Surrounding Rock

2013 ◽  
Vol 353-356 ◽  
pp. 1749-1752
Author(s):  
Yu Cheng Zhao ◽  
Dan Feng Lu ◽  
Yao Chen
Keyword(s):  
Numerical Simulation ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Equivalent Plastic Strain ◽  
Surrounding Rock ◽  
Ansys Software ◽  
Stress Strain ◽  
Roadway Safety ◽  
Reasonable Range ◽  
Bolt Support

Bolt design has an important role to give full play to the effect of bolt support and ensure the roadway safety. Based on numerical simulation by ANSYS software, stress - strain is no longer as the analysis object in the study, but creating the paths mapped equivalent plastic strain to observe the changes in the plastic zone. This paper studies the influence of bolt direction on the surrounding rock, and proposes a reasonable range of support direction to provide a reference for the actual bolt. The result has shown that the large oblique bolt results in the equivalent plastic strain increasing and it is not conducive to control the deformation of the surrounding rock. The best supporting direction is from-30 ° to 30 °.

Numerical Simulation of Stress-Strain of AZ31 Mg Alloy Profile during Warm Tension-Rotation Bending Process

2013 ◽  
Vol 690-693 ◽  
pp. 2379-2382
Author(s):  
Han Xiao ◽  
Long Biao Wu
Keyword(s):  
Numerical Simulation ◽  
Plastic Strain ◽  
Tangential Stress ◽  
Cross Section ◽  
Equivalent Plastic Strain ◽  
Mg Alloy ◽  
Stress Strain ◽  
Az31 Mg Alloy ◽  
Bending Process ◽  
Distribution Of Stress

The warm tension-rotation bending process of AZ31 Mg alloy profile was simulated. The distribution of stress and equivalent plastic strain of the profile during the bending process were analyzed. The results indicate that tangential stress of cross-section of profile from the inside to outside after bending is shown as "tensile-compression-tensile-compression", which is appeared as "N"-shaped. Equivalent plastic strain of the outside of profile is maximum, which is 0.132; the inside of profile is lower, which is 0.069; the middle of profile is minimum, which is 0.003.

Influence of Elastic-Plastic Bending on the Relationship Between Applied Load and Maximum Bending Stress for Straight and Curved Bars

2020 ◽  
Author(s):  
Don Metzger
Keyword(s):  
Plastic Strain ◽  
Plastic Zone ◽  
Yield Point ◽  
Cross Section ◽  
Applied Load ◽  
Bending Stress ◽  
Stress Strain ◽  
Bending Load ◽  
Bending Capacity ◽  
The Relationship

Abstract Bending capacity in excess of the load required to cause yielding is due to a combination of work hardening and the effect of the plastic zone spreading toward the neutral axis. For materials of sufficiently high ductility, a fully developed plastic zone is achieved and the bulk of the section is stressed beyond yield. For lower ductility materials, failure may occur prior to full development of the plastic zone such that only a fraction of the cross section is at or above the yield stress. In such cases, the relationship between applied load and maximum bending stress becomes sensitive to the shape of the stress-strain curve near the yield point. This relationship is examined for straight and curved bars of rectangular and trapezoidal cross-section for tensile stress-strain curves characterized by nonlinear functions. The stress distribution as a function of applied load is determined analytically by enforcing moment equilibrium across the section. The strain distribution is determined through the classical condition of “planes remain plane” during deformation. The solutions provide analytically smooth load curves such that maximum stress can be directly plotted as a function of applied load. These plots exhibit three distinct regimes of response: 1) elastic, 2) development of plastic zone, and 3) fully developed plastic zone. Since the response is analytically smooth, the detailed relationship through the knee of the tensile curve can be examined. The results indicate that bending capacity is influenced significantly by the development of small amounts of plastic strain prior to reaching a yield point defined by the usual 0.2% plastic strain offset method. The results also show how loss of ductility with respect to tensile elongation translates into reduced bending load capacity in a non-linear relationship.

scholarly journals Deviatoric Stress Evolution Laws and Control in Surrounding Rock of Soft Coal and Soft Roof Roadway under Intense Mining Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Dongdong Chen ◽  
Chunwei Ji ◽  
Shengrong Xie ◽  
En Wang ◽  
Fulian He ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Plastic Zone ◽  
Theoretical Calculations ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Deviatoric Stress ◽  
Anchor Cable ◽  
Soft Coal ◽  
Working Face ◽  
Failure Line

Aiming at the problem of large deformation and instability failure and its control of soft coal and soft roof roadway under intense mining, laboratory experiments, theoretical calculations, Flac3D numerical simulation, borehole peeping, and pressure observation were used to study the deflection characteristics of the deviatoric stress of the gas tailgate and the distribution and failure characteristics of the plastic zone in the mining face considering the strain softening characteristics of the roof and coal of roadway, and then the truss anchor cable-control technology is proposed. The results show the following: (1) The intense mining influence on the working face will deflect the peak deviatoric stress zone (PDSZ) of the surrounding rock of the gas tailgate. The influence distance of PDSZ is about 20 m in advance and 60 m in lag; the PDSZ at the gob side of the roadway is located in the range of 3–5.5 m from the surface of the coal pillar, while the coal wall side is mainly located in the range of 3–4.5 m at the shoulder corner and bottom corner of the solid coal. (2) The intense mining in the working face caused the nonuniform expansion of the surrounding rock plastic area of the gas tailgate. The two shoulder angles of the roadway and the bottom of the coal pillar have the largest damage range, and the maximum damage location is the side angle of the coal pillar (5 m). Angle and bottom angle of coal pillar are the key points of support control. (3) The plastic failure line of the surrounding rock of the gas tailgate is always between the inner and outer contours of the PDSZ, and the rock mass in the PDSZ is in a stable and unstable transition state, so the range of anchor cable support should be cross plastic failure line. (4) The theoretical calculations and numerical simulation results agree well with the drilling peep results. Based on the deflection law of the PDSZ and the expansion characteristics of the plastic zone, a truss anchor cable supporting system with integrated locking and large-scale support function is proposed to jointly control the roof and the two sides, which effectively solves the problem of weak surrounding rock roadway under severe mining deformation control problems realizing safety and efficient production in coal mines under intense mining.

Numerical Analysis of Damage for Y-Shape Tunnel

2011 ◽  
Vol 368-373 ◽  
pp. 2517-2520
Author(s):  
Da Ming Lin ◽  
Yan Jun Shang ◽  
Guo He Li ◽  
Yuan Chun Sun
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Numerical Analysis ◽  
Plastic Zone ◽  
Comprehensive Analysis ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Deformation And Failure ◽  
Single Beam ◽  
Flac 3D

There are many effective researches about tunnel at home and abroad, because the complexity of design and construction for Y-shape tunnel, in public there is no research about it yet, with the background of nanliang-tunnel which merge two single-beam into a two-lane tunnel as Y-shape. This paper obtains the rock mass mechanics parameters on the basis of nonlinear Hoek-Brown criterion first, and has a numerical simulation according the tunnel construction with FLAC-3D. we arrange many monitor sections in this model and discuss the law of deformation and failure in different section, at last have a comprehensive analysis of displacement, stress, plastic zone of different sites which caused by tunnel construction and discover that: with the distance of two single tunnels decreased, the interaction caused by the merging increase together with the compressive stress, tensile stress. The displacements of surrounding rock increase corresponding, the amplitude of variation is up to 44.8%, After the two-lane tunnel is 15m long, the stress and displacements redistribution of surrounding rock become stable.

Study on Influence of Rock Strength on Anchorage Performance of Resin Anchored Bolts

2014 ◽  
Vol 962-965 ◽  
pp. 968-972
Author(s):  
Bin Hu
Keyword(s):  
Numerical Simulation ◽  
Finite Difference ◽  
Plastic Zone ◽  
Rock Strength ◽  
Soft Rock ◽  
Support Effect ◽  
Surrounding Rock ◽  
Small Scale ◽  
Stress Distributions ◽  
Anchorage Length

Based on the introduction of the researches on the influence of the surrounding rock strength on the anchorage performance of resin anchored bolts at home and abroad, the numerical simulation was adopted to analyse anchorage system of single bolt support small-scale by using the finite difference program FLAC3D. The results showed that the stress distributions in resin capsules and surrounding rocks were different with the different strengths of surrounding rocks. The stresses in the surrounding rocks gradually decreased with the reduction of rock strength, but the plastic zone gradually expanded. On the basis, such technological approaches were brought forward to ensure support effect in the soft rock roadways by improving the materials and formulations of the resin capsules and increasing the support density and the anchorage length appropriately.

Numerical Simulation Study of Quasi-Static Loading and Dynamic Loading for Micro Bending Forming of Copper Foil

2016 ◽  
Vol 723 ◽  
pp. 503-511
Author(s):  
Wen Hao Zhang ◽  
Qing Qian ◽  
Zong Bao Shen ◽  
You Juan Ma ◽  
Hui Xia Liu
Keyword(s):  
Numerical Simulation ◽  
Plastic Strain ◽  
Strain Rate ◽  
Dynamic Loading ◽  
Static Loading ◽  
Shock Loading ◽  
Equivalent Plastic Strain ◽  
Plastic Strain Rate ◽  
Laser Shock ◽  
Feature Size

A variety of micro forming processes has been invented, and the size effects have become a research hotspot at home and abroad. Micro bending molds with different feature sizes were designed. Quasi-static tester loading and dynamic laser shock loading with soft punch for micro bending forming was studied by numerical simulation respectively based on ANSYS implicit analysis and LS-DYNA explicit analysis. The constitutive models of workpiece are bilinear kinematic hardening model and Johnson-cook model respectively. The effects of different loading conditions and feature sizes of the die on the forming depth, equivalent plastic strain and equivalent plastic strain rate were studied. The results of numerical simulation show that, with the increasing of feature size of the mold, the forming depth under two kinds of loading conditions shows a tendency to increase. In dynamic laser shock loading, the equivalent plastic strain and equivalent plastic strain rate of the key position of the bent part would decrease with the increasing of the feature size of the die. While in quasi-static loading, the opposite law is shown. The research shows that, the flexible micro-bending processes with different loading models showed similar size effect. However, compared with quasi-static loading, in dynamic loading, the strain of forming parts is more centralized, and there is a high strain rate and better formability of the workpiece.

An experimental and numerical investigation on impact spot welding of metallic plates using gas mixture detonation technique

2020 ◽  
pp. 146442072098232
Author(s):  
Sedigheh Hosseinzadeh ◽  
Hashem Babaei ◽  
Tohid Mirzababaie Mostofi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Plastic Strain ◽  
Spot Welding ◽  
Equivalent Plastic Strain ◽  
Welding Process ◽  
Gas Mixture ◽  
The Impact ◽  
Base Plates ◽  
Metallic Plates

In this paper, the impact spot welding of metallic plates was investigated both experimentally and numerically using a single-stage gas mixture detonation apparatus. The impact spot welding process was carried out on aluminum alloy and steel materials using rigid steel projectiles. In this process, the mixture of oxygen and acetylene was detonated in a combustion chamber to launch the projectile. The masses of flat- and spherical-nosed projectiles were 270 and 230 g, respectively. The impact velocity was measured in all experiments. The cross-sections of the weld spots were inspired by a scanning electron microscope to assess the quality of welding. For several experiments, wavy interfaces were observed showing there is a good bonding. For numerical simulation of the process, Abaqus/Explicit software was used and the deformation and failure mechanisms of impact spot-welded specimens were further investigated. The Johnson–Cook thermoplasticity model along with its failure model was utilized to predict the behavior of metallic materials. The numerical simulation results were in good agreement with those obtained from experiments in terms of the deformation mode and failure pattern. The propagation of the wave on the surface of the flyer plate was further studied. The results showed that the stress waves start from the center and propagate to the corners of the plate. To numerically evaluate the welding quality, two parameters of the shear stress at the collision point as well as the equivalent plastic strain for the flyer and target plates were obtained in the numerical simulation. The numerical results showed opposite directions of shear stress for flyer and base plates at the contact point, which can be used as proof for good bonding. Besides, the magnitudes of the equivalent plastic strain for both flyer and base plates were higher than those reported values in the open literature that confirms successful welding.

scholarly journals Stability Analysis of Underground Pillar Supporting System under Different Disturbed Stresses

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Yang Li ◽  
Limin Liu ◽  
Jinpeng Zhang ◽  
Chuanxiao Liu ◽  
Mengyao Zhang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Maximum Stress ◽  
Equivalent Plastic Strain ◽  
Stress Transfer ◽  
Mechanical Analysis ◽  
External Disturbances ◽  
Supporting System ◽  
Increase Rate

Small external disturbances may destabilize the bearing pillar, which in turn will change the stress distribution of the pillar supporting system, leading to its overall instability. Based on the engineering background of a mine and the mechanical analysis of pillar under disturbed stress, this paper investigated the stress, strain, and plastic zone of the pillar supporting system under different disturbed stresses. Then, the chain instability of the pillar supporting system was achieved. The law of stress transfer and plastic development of the pillar supporting system was explored. The results showed that the greater the disturbed stress, the faster the increase rate of the maximum stress of the pillar supporting system. As the width of the pillar increased, the maximum stress of the pillar decreased, so its risk of damage decreased. As the disturbed stress increased, the maximum principal strain and equivalent plastic strain of the 6 m wide pillar increased approximately linearly, and their growth rates of the 4 m wide pillar gradually increased. In the process of chain instability of the pillar supporting system, the sides of the middle pillar were destroyed first, and then the plastic zone gradually penetrated, causing the stress of the adjacent pillar to increase, which in turn led to its destruction. By analyzing the monitoring data of stress, displacement, or plastic strain, the instability of the pillar can be predicted.

The Numerical Study of the Stability of Roadway Seeping in the Roof

2012 ◽  
Vol 178-181 ◽  
pp. 1293-1296
Author(s):  
Feng Zhen Liu ◽  
Wei Guo Qiao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Plastic Zone ◽  
Numerical Study ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Key Factors ◽  
Roadway Stability ◽  
The Stability ◽  
Roadway Deformation

Seepage in the roof is one of main reasons resulting softening rock and roadway deformation, in order to make sure about the influence of seepage on the roadway stability, we established corresponding models by using numerical simulation software, and analyzed the stress distribution, the deformation of surrounding rock, and the distribution range and shape of the plastic zone, the results show that water is one of the key factors to influence the stability of roadway, seepage makes the strength of surrounding rock sharply reduce, and the roof, two ribs and floor appear serious deformation.

Numerical Simulation Analysis of the Nanyangpo Coal Mine Anchor Support Method

2012 ◽  
Vol 619 ◽  
pp. 231-238
Author(s):  
Mei Chang Zhang ◽  
Peng Cheng Fei ◽  
De Long Zou
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Nursing Program ◽  
Load Carrying ◽  
Deformation Law ◽  
The Stability ◽  
Surrounding Rock Deformation ◽  
Bolt Support

The bolt support is important to ensure the stability of surrounding rock. Of Nan Yangpo mines as the research background. The application of numerical simulation software FLAC3D mine deep Bolt bolt support after the surrounding rock deformation law of the numerical simulation, Comparison and analysis of rock displacement and plastic zone under the support program changes. The results show that, The third bolt support nursing program, Significantly improve the strength and load carrying capacity of the surrounding rock, Effectively control the damage of the deep tunnel deformation that can control the roof of 4101 the return airway and two to help the stability.

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