scholarly journals The influence law of eccentric load on the performance of yielding bolt

2020 ◽  
Vol 7 (7) ◽  
pp. 200227
Author(s):  
Yang Tai ◽  
Hongchun Xia ◽  
Shaoping Huang ◽  
Jie Meng ◽  
Wei Li
Keyword(s):  
Numerical Simulations ◽  
Large Deformation ◽  
Absorptive Capacity ◽  
High Stress ◽  
Utilization Rate ◽  
Plastic Strains ◽  
Eccentric Load ◽  
Yielding Point

In order to adapt to the high stress and avoid the large deformation in roadways, the pre-stressed yielding bolt has been developed. Prior to the installation of the pre-stressed yielding bolt, boreholes need to be drilled. However, not all boreholes are perpendicular to the surface of the roadway, and the non-perpendicular holes make the pre-stressed yielding bolt exposed to eccentric loads. In order to reveal the influence of the eccentric load on the performance of the pre-stressed yielding bolt, some numerical simulations were carried out in this study. The influence of the eccentric load on the displacement–load relations, utilization rate of the yielding pipe, the plastic strains of the bolt components as well as the evolution of the absorptive capacity of the yielding pipe were analysed. The results are as follows: (i) eccentric loads affected the utilization rate of the yielding pipe, plastic strains of bolt components and the absorptive capacity was quite great when displacement was less than 2 mm, while these impacts could be neglected when displacement is greater than 2 mm; (ii) as the eccentric load increased, the yielding point and its corresponding displacement increased linearly while the yielding magnitude decreased linearly; and (iii) the eccentric load could be adjusted to control the yielding point and magnitude in order to meet the roadway support's requirement for the yielding bolt.

scholarly journals Research on Control Mechanism of Surrounding Rock of Deep Gob-Side Entry Retaining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jianxiong Liu ◽  
Jingke Wu ◽  
Yun Dong ◽  
Yanyan Gao ◽  
Jihua Zhang ◽  
...  
Keyword(s):  
Large Deformation ◽  
High Stress ◽  
Original System ◽  
Field Investigation ◽  
Surrounding Rock ◽  
Eccentric Load ◽  
Deformation And Failure ◽  
Body Fracture ◽  
Stress States ◽  
Term Creep

To address the large deformation of the surrounding rock of deep gob-side entry retaining under high stress, lithological characteristics of the surrounding rock and failure model of support body and their evolutionary processes are analyzed through field investigation and theoretical analysis. Failure mechanisms of surrounding rock and the technology to control it are studied systematically. The results show that the causes of the large deformation of the surrounding rock are weak thick mudstones with softening property and water absorption behavior, as well as its fragmentation, dilatancy, and long-term creep during strong disturbance and highly centralized stress states. The cross-section shape of the roadway after deformation and failure of the surrounding rock is obviously asymmetric in both the horizontal and vertical directions. Since the original system supporting the surrounding rock is unable to completely bear the load, each part of the supporting system is destroyed one after the other. The failure sequences of the surrounding rock are as follows: (1) roadway roof fracture in the filling area, (2) filling body fracture under eccentric load, (3) rapid subsidence of the roadway roof, and (4) external crack drum and rib spalling at the solid coal side. Due to this failure sequence, the entire surrounding rock becomes unstable. A partitioned coupling support and a quaternity control technology to support the surrounding rock are proposed, in which the roof of the filling area plays a key role. The technology can improve the overall stability of gob-side entry retaining, prevent support structure instability caused by local failure of the surrounding rock, and ensure the safety and smoothness of roadways.

Effects of conform, non-conform, and hybrid conformity toward stress distribution at the glenoid implant and cement: A finite element study

2021 ◽  
pp. 039139882199939
Author(s):  
Abdul Hadi Abdul Wahab ◽  
Nor Aqilah Mohamad Azmi ◽  
Mohammed Rafiq Abdul Kadir ◽  
Amir Putra Md Saad
Keyword(s):  
Stress Distribution ◽  
Daily Living ◽  
3D Model ◽  
Promising Result ◽  
High Stress ◽  
Constant Load ◽  
Posterior Region ◽  
Implant Stability ◽  
Eccentric Load ◽  
Standing Up

Glenoid conformity is one of the important aspects that could contribute to implant stability. However, the optimal conformity is still being debated among the researchers. Therefore, this study aims to analyze the stress distribution of the implant and cement in three types of conformity (conform, non-conform, and hybrid) in three load conditions (central, anterior, and posterior). Glenoid implant and cement were reconstructed using Solidwork software and a 3D model of scapula bone was done using MIMICS software. Constant load, 750 N, was applied at the central, anterior, and posterior region of the glenoid implant which represents average load for daily living activities for elder people, including, walking with a stick and standing up from a chair. The results showed that, during center load, an implant with dual conformity (hybrid) showed the best (Max Stress—3.93 MPa) and well-distributed stress as compared to other conformity (Non-conform—7.21 MPa, Conform—9.38 MPa). While, during eccentric load (anterior and posterior), high stress was located at the anterior and posterior region with respect to the load applied. Cement stress for non-conform and hybrid implant recorded less than 5 MPa, which indicates it had a very low risk to have cement microcracks, whilst, conform implant was exposed to microcrack of the cement. In conclusion, hybrid conformity showed a promising result that could compromise between conform and non-conform implant. However, further enhancement is required for hybrid implants when dealing with eccentric load (anterior and posterior).

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

Numerical Simulations of Dynamic Fracture in Thin Pipes

2009 ◽  
Author(s):  
Y. Shie
Keyword(s):  
Numerical Simulations ◽  
Large Deformation ◽  
Dynamic Fracture ◽  
Thin Shell ◽  
Large Scale ◽  
Shell Structures ◽  
Theory Approach ◽  
Continuum Approach ◽  
Ill Conditioning ◽  
High Flexibility

We present a meshless methodology for large scale computations of fractureing thin shell structures subjected to internal pressure loads. The contribution is the first step of an efficient numerical methodology for such kind of events. In this paper, numerical simulations of large deformation dynamic fracture in thin shell structures using 3-D meshfree methods is presented. Due to the smoothness of the meshfree shape functions, they are well suited to simulate large deformation of thin shell structures while avoiding ill-conditioning as well as stiffening in numerical computations. The 3D meshfree representation allows high flexibility since thin structures as well as thick structures can be studied by the same methodology. The meshfree approach makes the methodology more flexible and independent as compared to finite elements, i.e. there is no need for creation of mesh. Dynamic fracture is modeled by a simple criterion, i.e. removing connectivity between adjacent nodes once a fracture criterion is met. The main advantage of such a 3-D meshfree continuum approach is its simplicity in both formulation and implementation as compared to shell theory approach, or degenerated continuum approach. Moreover, it is believed that the accuracy of the computation may increase because of using 3-D exact formulation.

Study on the Supporting Technology of Complex Deep Coal Roadways

2012 ◽  
Vol 524-527 ◽  
pp. 743-746
Author(s):  
Zhi Yang Liu
Keyword(s):  
Large Deformation ◽  
Experimental Test ◽  
High Stress ◽  
Surrounding Rock ◽  
Abscission Layer ◽  
Ground Pressure ◽  
Pressure Water ◽  
Observation Results

Suffering from the effect of the high ground pressure, water spraying from roof surrounding rock or geological tactics such as faults or collapse columns, roadways used to have large deformation, even lead to caving accidents. Based on the supporting research of the above complex conditions, the supporting background of a typical roadway No.202 affected by high stress, water spraying and large faults is analyzed and the corresponding technology is put forward. In addition, the support experimental test is conducted on the roadway, and the observation results show that the convergence of both sides is controlled well, and abscission layer is little.

scholarly journals Numerical Simulations of 3D Metallic Auxetic Metamaterials in both Compression and Tension

2016 ◽  
Vol 846 ◽  
pp. 565-570 ◽  
Author(s):  
Xin Ren ◽  
Jian Hu Shen ◽  
Arash Ghaedizadeh ◽  
Hong Qi Tian ◽  
Mike Xie
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulations ◽  
Large Deformation ◽  
Scale Factor ◽  
Research Interest ◽  
Preliminary Results ◽  
Auxetic Materials ◽  
Tension And Compression ◽  
Pattern Scale ◽  
Intense Research

Auxetic materials exhibit uncommon behaviour, i.e. they will shrink (expand) laterally under compression (tension). This novel feature has attracted intense research interest. However, most of previous works focus on auxetic behaviour in either compression or tension. Most of the auxetic materials are not symmetric in tension and compression under large deformation. Studies on the auxetic performance of metamaterials both in compression and tension are important but rare. As an extension of our previous research on compressive auxetic performance of 3D metallic auxetic metamaterials, numerical simulations were carried out to investigate the auxetic and other mechanical properties of the 3D metallic auxetic metamaterials in tension. The preliminary results indicated that the designed 3D metallic auxetic metamaterials exhibited better auxetic performance in compression than in tension. By increasing a pattern scale factor, auxetic performance of the 3D metallic auxetic metamaterials under tension can be improved. With proper adjustment of the pattern scale factor, an approximately symmetric auxetic performance could be achieved in compression and tension.

Simulation Research on Stress of Polymeric Patterns during Micro Hot Embossing

2011 ◽  
Vol 80-81 ◽  
pp. 339-345 ◽  
Author(s):  
Ting Zhang ◽  
Yong He ◽  
Jian Zhong Fu
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
High Stress ◽  
Hot Embossing ◽  
Duty Ratio ◽  
Simulation Research ◽  
High Stress Concentration ◽  
Simulation Results

The properties of polymeric components made by hot embossing are obviously affected by the geometry of the mold such as the duty ratio, the aspect ratio, width to thickness ratio and the mold cavity position. This paper focuses on numerical simulations with isothermal embossing conditions in order to observe the stress distribution and the stress concentration of the polymeric patterns. The simulation results show that stress concentration in the PMMA resist accumulates at the contact corner between the mold and the polymer, and the location of the stress distribution is mainly on the profile of the replicated patterns. Small duty ratio will result in high stress concentration at the corner of the replicated components. The stress concentration also increases rapidly while the aspect ratio of the mold increases. The thicker the polymer is, the more difficult the adequate flow of the polymer becomes, and the stress concentration rises up. A stress barrier can be used in the mold in order to reduce the stress concentration in the middle of the replicated polymeric patterns.

scholarly journals Vibration isolation characteristics and control strategy of parallel air spring system for transportation under abnormal road and eccentric load conditions

2021 ◽  
pp. 002029402199663
Author(s):  
Di Qu ◽  
Xiandong Liu ◽  
Guangtong Liu ◽  
Tian He
Keyword(s):  
Large Deformation ◽  
Control Strategy ◽  
Vibration Isolation ◽  
Air Spring ◽  
Eccentric Load ◽  
Height Control ◽  
Precision Equipment ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Equal Height

The precision equipment bears the vibration excited by the road roughness during transportation, and faces the risk of damage arising from the vibration. The parallel air spring vibration isolation system (PAVS) has an excellent vibration isolation performance, so has a good application prospect in the precision equipment transportation. But under the conditions of abnormal road and eccentric load, PAVS bears great vibration excitation, and the resulting large deformation of air spring makes the air spring stiffness nonlinear, so to obtain an excellent vibration isolation performance faces a great challenge. Aiming at this problem, based on the measured parameters, the nonlinear dynamics model of PAVS is proposed. Then, the influence of air spring under large deformation on the vibration isolation characteristics is discussed. Finally, under the condition of eccentricity of precision equipment, the vibration isolation characteristics of PAVS with equal height control strategy is investigated. The results show that PAVS with the equal height control strategy has good vibration isolation characteristics. So for the transportation of large precision equipment, PAVS is a potentially useful method.

scholarly journals Numerical Analysis of the Width Design of a Protective Pillar in High-Stress Roadway: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
FuZhou Qi ◽  
ZhanGuo Ma ◽  
Ning Li ◽  
Bin Li ◽  
Zhiliu Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Energy Density ◽  
Large Deformation ◽  
High Stress ◽  
Vertical Stress ◽  
Pillar Width ◽  
Modeling Approach ◽  
Roadway Stability ◽  
The Stability

The width design of protective pillars is an important factor affecting the stability of high-stress roadways. In this study, a novel numerical modeling approach was developed to investigate the relationship between protective pillar width and roadway stability. With the 20 m protective pillar width adopted in the field test, large deformation of roadways and serious damage to surrounding rocks occurred. According to the case study at the Wangzhuang coal mine in China, the stress changes and energy density distribution characteristics in protective pillars with various widths were analysed by numerical simulation. The modeling results indicate that, with a 20 m wide protective pillar, the peak vertical stress and energy density in the pillar are 18.5 MPa and 563.7 kJ/m3, respectively. The phenomena of stress concentration and energy accumulation were clearly observed in the simulation results, and the roadway is in a state of high stress. Under the condition of a 10 m wide protective pillar, the peak vertical stress and energy density are shifted from the pillar to roadway virgin coal region, with peak values of 9.5 MPa and 208.3 kJ/m3, respectively. The decrease in vertical stress and energy density improves the stability of the protective pillar, resulting in the roadway being in a state of low stress. Field monitoring suggested that the proposed 10 m protective pillar width can effectively control the large deformation of the surrounding rock and reduce coal bump risk. The novel numerical modeling approach and design principle of protective pillars presented in this paper can provide useful references for application in similar coal mines.

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