Evaluation of Stress and Stress Concentration Degree Based on the Online Piezomagnetic Measurement

2021 ◽  
pp. 1-13
Author(s):  
Sheng Bao ◽  
Qiang Luo ◽  
Zhengye Zhao ◽  
Yibin Gu
Keyword(s):  
Stress Concentration ◽  
Concentration Degree

Finite Element Analysis of the Shell of GIS Busbar Tube

2014 ◽  
Vol 889-890 ◽  
pp. 1406-1409 ◽  
Author(s):  
Ming Jian Jian ◽  
Guang Cheng Zhang ◽  
Du Qing Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Gas Pressure ◽  
Thickness Direction ◽  
Element Analysis ◽  
Finite Element Software ◽  
Concentration Degree ◽  
Inside Out

By finite element software ANSYS a model of GIS busbar tube was established for investigating the effect of the gas pressure on the shell. The results shows that the stress concentration degree is higher on the shoulder between the main tube and the branch pipes under the internal pressure and the gravity, and the highest value is 44.92MPa which is far lower than the admissible stress. Stress changed along the thickness direction, and its value decreased gradually from the inside out. The distributions of the strain and deformation are similar to that of the stress.

scholarly journals Investigation of Stress Concentration and Casing Strength Degradation Caused by Corrosion Pits

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Wei Yan ◽  
Yun Xu ◽  
Yi Zhou ◽  
Kongyang Wang
Keyword(s):  
Stress Concentration ◽  
Pitting Corrosion ◽  
Strength Degradation ◽  
Corrosive Environment ◽  
Collapse Load ◽  
Mechanical Loads ◽  
Inner Surface ◽  
Casing Strength ◽  
Concentration Degree ◽  
Corrosion Pits

Downhole casing and tubing are subjected to corrosion in many cases because of the exposure to corrosive environment. A more serious problem is that pitting corrosion occurs in the casing inner surface. Meanwhile, downhole strings are subjected to various forms of mechanical loads, for example, internal pressure load, external collapse load, or both. These loads acting on the corrosion pits will cause stress concentration and degrade the casing strength. Thus, it is essential to evaluate the stress concentration degree reasonably. The SCF (stress concentration factor) is usually used to characterize the degree of stress concentration induced by corrosion pits. This paper presented a comparison on the SCFs regarding the analytical method for a single pit and experimental method for double pits. The results show that the SCF of a single pit depends mainly on the depth of the corrosion pit; however, the SCF of the double pits strongly depends on the pits distance. A correction factor of 1.3 was recommended in the double pits SCF prediction model.

Research on Reasonable Position of Roadway for close Multi-Seam and its Application

2013 ◽  
Vol 807-809 ◽  
pp. 2393-2397
Author(s):  
Ai Qing Liu
Keyword(s):  
Stress Concentration ◽  
Coal Seam ◽  
Abutment Pressure ◽  
Dynamic Pressure ◽  
Coal Pillar ◽  
Stress Zone ◽  
Concentration Degree ◽  
Residual Coal

The principle of roadway layout is in the low stress zone. Roadway will be difficult to support due to the lower seam face in the close multi-seam is affected by dynamic pressure of the upper seam face mining. The distribution of abutment pressure after the upper seam face mining were analyzed,concluded that: The layout of lower seam roadway should avoid the stress concentration area of residual coal pillar; Stress concentration of the coal pillar is related with mining order, and stress concentration degree is higher in the first mining side of the coal pillar; when the upper coal seam is gob, the layout of the roadway in the lower coal seam with the pattern of homodromous alternate interior layout will be easy to support.

Three Dimensional Numerical Simulation of Rock Core Discing Based on Strain Soft Model

2011 ◽  
Vol 187 ◽  
pp. 565-569
Author(s):  
An Nan Jiang ◽  
Zheng Wen Zeng
Keyword(s):  
Numerical Simulation ◽  
Stress Concentration ◽  
Three Dimensional ◽  
Drilling Depth ◽  
Feedback Analysis ◽  
Concentration Degree ◽  
Pressure Stress ◽  
Core Discing

Aiming at the complexity of rock discing mechanics, and the theory being not mature, the paper carried out three-dimensional numerical simulation for rock core discing based on strain soft model. The strain soft theory is introduced firstly, then numerically simulated how the depth of lug boss and original stress affect the rock core destroy pattern(discing if occurs, the thickness of disk), obtained the characters of rock core discing. Along with the drilling depth increases, the stress concentration scope below lug boss also increases, as well as the pressure stress concentration degree of side corner below of lug boss. Rock core discing can be induced respectively by shear action and tension action, sometimes it is combined by both of them. The destroy pattern of them especially destroy sequence are different. The strain soft numerical simulation could be used in original stress feedback analysis, has significant meaning.

scholarly journals Study on the Relationship between Stress and Charge of Coal Mass under Uniaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Gang Wang ◽  
Yishan Pan ◽  
Xiaochun Xiao ◽  
Di Wu ◽  
Hongrui Zhao ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Laboratory Test ◽  
Coal Mine ◽  
Coal Mass ◽  
Average Charge ◽  
Working Face ◽  
Close Relationship ◽  
Concentration Degree ◽  
The Relationship

This paper presents a new method to identify the stress concentration degree and stress distribution characteristics in front of working face in coal mine, based on the close relationship between charge and stress during fracture of coal mass. This method overcomes many disadvantages of conventional stress-monitored methods. First, the stress and charge relationship of coal mass was established through damage theory and statistical strength theory. Then, the relationship between stress and charge was studied by a laboratory test, and finally, the field charge monitoring test was performed. The results show that there is a nonlinear relationship between loading stress (σ) and cumulative charge (Q), which can be represented by polynomials. The fitting results of the laboratory test between σ and Q conform to a cubic polynomial function, Q=aσ3+bσ2+cσ+d. It verifies the rationality of the theoretical relationship formula. The field monitoring results show that average charge is great and cumulative charge changes from rapid upward to sharp upward before roof falling. The magnitude and position of average charge and the upward trend of cumulative charge can be used to identify the stress concentration and stress distribution in front of working face, and the abnormal stress area can be predicted. The results can provide certain guidance for the forecast of rock burst in coal mine.

Simulation Study on the Stability of Mining Thin Flat-Grade Iron Ore Body with Hydraulic Support Longwall Method

2012 ◽  
Vol 170-173 ◽  
pp. 3706-3710
Author(s):  
Shu Guo Zhao ◽  
Wei Dong Song ◽  
Wen Bin Xu ◽  
Huan Hu Song
Keyword(s):  
Stress Concentration ◽  
Simulation Method ◽  
Small Range ◽  
Rock Stress ◽  
Coal Face ◽  
Hydraulic Support ◽  
Plastic Zones ◽  
Concentration Degree ◽  
Mining Face ◽  
The Stability

This paper proposed hydraulic support longwall method for mining glacis thin orebody. The DaZhuang ore section of Guandian Ore Mining whose orebody in the line of -8＇—-16＇was chosen as the research object. It applied the FLAC numerical simulation method to study the changes of surrounding rock stress in the mining face, displacement and plastic zones, and put forward the changing law of the rock stress, displacement and plastic zones in the mining process. Besides, it proved that the mechanical condition of the roofs changed in different stages. When the distance between pillar and mining face was in the range of 4m—8m, the state was relatively stable, and the pillar and surrounding rocks were in small range of shearing and tensile yield. When distance was 12m, the roof suffered from compression. When it was up to 16m, the roof and bottom rock displayed tension. However，the appreciation of stress changed very little at different stages. The stress concentration circle formed between the top and bottom of the pillar, and the unloading appeared in the top and bottom gap. The nearer to the coal face, the more powerful of stress concentration, and the influence of pillar’s position on stress concentration degree is very little in the front of coal face. The structure would be in stable equilibrium when the distance between single stent and coal face is 12m. In such circumstances, the security of roof would be improved if more stents are added

Correlation Between Stress Concentration Degree and Residual Magnetic Field

2016 ◽  
Author(s):  
Sheng Bao ◽  
Ashri Mustapha ◽  
Huangjie Lou
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Tensile Tests ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Residual Magnetic Field ◽  
Concentration Degree ◽  
Qualitative Relationship ◽  
Ferromagnetic Steels

In this research, the correlation between the stress concentration degree and the residual magnetic field (RMF) of ferromagnetic steels is investigated. Tensile tests were carried out to measure the RMF signals on the surface of steel specimens with different stress concentration degrees. The effectivity of the metal magnetic memory (MMM) technique in defective specimens was investigated in comparison with a non-defective specimen. Analysis of the qualitative relationship between the stress concentration degree and the RMF components was subsequently performed on two types of defective specimens. The qualitative correlation between the planar distributions of the RMF components and the stress concentration degree was further studied. It was validated that both the RMF signal and its planar distribution are effective in characterizing the stress concentration degree. The results obtained in this research will be a complement to the MMM technique.

Characterization of Stress Concentration Degree Based on 2-Dementional Magnetic Memory Signals

2012 ◽  
Vol 268-270 ◽  
pp. 396-400 ◽  
Author(s):  
Hui Peng Wang ◽  
Li Hong Dong ◽  
Shi Yun Dong ◽  
Nan Xue ◽  
Bin Shi Xu
Keyword(s):  
Stress Concentration ◽  
Fatigue Test ◽  
Tangential Component ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Concentration Factors ◽  
Memory Signals ◽  
Concentration Degree ◽  
Stress Concentration Factors ◽  
Peak Value

To explore a way to characterize fatigue damage degree of ferromagnetic materials by metal magnetic memory testing (MMMT), tension-compression fatigue test of specimens with different stress concentration factors made of 45% C steel were carried out. Both normal and tangential component of magnetic memory signals, Hp(y) and Hp(x), of specimens under different fatigue cycles were measured by EMS-2003 and RM-1 magnetic memory testing apparatus respectively. The results show that, the gradient variation of Hp(y) signals during the fatigue test is similar to each other, but the gradient value is different due to the different stress concentration factors. And so is the relative peak value of Hp(x) signals. Both gradient of Hp(y) and relative peak value of Hp(x) can be used to distinguish the stress concentration degree of specimens.

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