scholarly journals Deformation Mechanism Analysis of Three-Roller Continuous and Synchronous Calibration Process of Straightness and Roundness For LSAW Pipes

2021 ◽  
Author(s):  
Xueying Huang ◽  
Gaochao Yu ◽  
Chunge Wang ◽  
Jun Zhao
Keyword(s):  
Deformation Mechanism ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Mechanism Analysis ◽  
Calibration Process ◽  
Theoretical Support ◽  
Bending Process ◽  
Axial Curvature ◽  
The Difference ◽  
Submerged Arc

Abstract Continuous and synchronous calibration process of straightness and roundness for LSAW (Longitudinally Submerged Arc Welding, LSAW) pipes with three rollers is a bidirectional reciprocating bending process that includes axial and circumferential directions. It is particularly important to reveal the deformation mechanism, which provides theoretical support for the calibration process to be applied to actual production. Based on this, through the combination of references, theoretical analysis and numerical simulation, the deformation mechanism is analyzed in this paper. The whole deformation process of pipe is modeled and then numerically simulated with FEM software of ABAQUS. The results show that reciprocating bending can eliminate the difference of initial curvature, so that the axial curvature and circumferential curvature are unified to the same direction and value respectively. The synergy between the axial reciprocating bending straightening process and the circumferential reciprocating bending rounding process realizes the calibration process of LSAW pipes. The simulation results support the theoretical results, and the deformation is mainly caused by axial stress and circumferential stress.

scholarly journals Thermoelastic analysis of FGM hollow cylinder for variable parameters and temperature distributions using FEM

2020 ◽  
Vol 9 (1) ◽  
pp. 256-264
Author(s):  
Dinkar Sharma ◽  
Ramandeep Kaur
Keyword(s):  
Stress Field ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Functionally Graded ◽  
Gradient Index ◽  
Variable Parameters ◽  
Graded Material ◽  
Governing Differential Equation

AbstractThis paper presents, numerical study of stress field in functionally graded material (FGM) hollow cylinder by using finite element method (FEM). The FGM cylinder is subjected to internal pressure and uniform heat generation. Thermoelastic material properties of FGM cylinder are assumed to vary along radius of cylinder as an exponential function of radius. The governing differential equation is solved numerically by FEM for isotropic and anistropic hollow cylinder. Additionally, the effect of material gradient index (β) on normalized radial stresses, normalized circumferential stress and normalized axial stress are evaluated and shown graphically. The behaviour of stress versus normalized radius of cylinder is plotted for different values of Poisson’s ratio and temperature. The graphical results shown that stress field in FGM cylinder is influenced by some of above mentioned parameters.

scholarly journals INTERVENSI KEBIJAKAN MONETER TERHADAP INVESTASI PORTOFOLIO: KASUS INDONESIA DAN AMERIKA SERIKAT

2020 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Nanda Alfarina ◽  
Hasdi Aimon
Keyword(s):  
United States ◽  
Interest Rate ◽  
Secondary Data ◽  
The United States ◽  
Portfolio Investment ◽  
Mechanism Analysis ◽  
Long Run ◽  
Negative Effect ◽  
The Difference ◽  
Effect Of Monetary Policy

This study aims to determine the effect of monetary policy measured by the central bank’s policy rate (X1) on portfolio investment (Y) in Indonesia and United States in the long run. The data used are secondary data seouced from SEKI BI, FRED The FEd, coinmarketcap.com, and investing.com, with the VECM (Vector Error Correction Mechanism) analysis methode. The study show The study shows the differences between the results that occur in Indonesia and the United States. The policy interest rate has a significant positive effect on portfolio investment in the long run in Indonesia, while in the United States the interest rate in the long run has a significant negative effect on portfolio investment. The difference in research results between the two countries shows the need for different treatment for monetary authorities in encouraging portfolio investment 

X-ray residual stress analysis of cylindrically curved surfaces—estimation of circumferential distributions of residual stresses

2003 ◽  
Vol 38 (5) ◽  
pp. 459-468 ◽  
Author(s):  
T Oguri ◽  
K Murata ◽  
Y Sato
Keyword(s):  
Residual Stresses ◽  
Least Squares Method ◽  
Stress Measurement ◽  
Incident Angle ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Distribution Functions ◽  
Scanning Method ◽  
X Ray ◽  
Reference Axis

A new measuring technique utilizing X-ray diffraction is proposed in order to estimate the circumferential distributions of residual stresses on convex/concave cylindrical surfaces. This technique requires neither tilting X-ray beams in the circumferential direction in which the X-ray incident angle tends to be limited nor adjusting the normal of the irradiation area to the reference axis of the ψ angle. The circumferential distributions of the circumferential stress and of the axial stress are estimated from the diffraction angles at ψ = 0° and the axial stresses obtained by the stress measurement on multiple inclined areas on the cylindrical surfaces under the configuration of the axial stress measurement using the iso-inclination scanning method. This estimate technique was applied to two round bars of steel, one with circumferential distributions of the residual stresses and the other with almost uniform stresses. The distribution functions of the residual stresses were expanded to a couple of Fourier series, and the coefficients of them were determined by the least-squares method. The estimated distributions of the residual stresses were in good agreement with the actual ones.

scholarly journals High-temperature axial stress evolution mechanism of polyacrylonitrile-based carbon fiber

2020 ◽  
Vol 15 ◽  
pp. 155892502094885
Author(s):  
Yu Wang ◽  
Lian-Wei Ye ◽  
Ru-yu Ruan ◽  
Ai-Jun Gao ◽  
Yuan-Jian Tong
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Carbon Fiber ◽  
Graphite Furnace ◽  
Axial Stress ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Stress Evolution ◽  
Carbon Structure ◽  
The Difference

Temperature and stretching are important factors in the high-temperature treatment of carbon fiber. The axial stress during carbon-fiber high-temperature treatment affects its ability to stretch. The high-temperature axial stress evolution mechanism of polyacrylonitrile-based carbon fiber was studied through in situ tension tests, Raman spectroscopy, X-ray diffractometry, elemental analysis, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, thermal expansion coefficient tests, and density methods. The high-temperature axial stress evolution of polyacrylonitrile-based carbon fiber involved three stages: rapid increase, rapid decrease, and relaxation. The highest stress and relaxation temperatures of the polyacrylonitrile-based carbon fiber were 1600°C and 1950°C, respectively. The main factors that affected the fiber axial stress included carbon-structure rearrangement and the effect of thermal expansion and cold shrinkage on fiber length. During the first stage ( T < 1600°C), carbon-structure rearrangement after nitrogen atom removal increased the fiber axial stress. In the second stage (1600 ⩽  T ⩽ 1950°C), the difference in the thermal expansion of fibers that entered the graphite furnace and the cold shrinkage of fibers that exited the graphite furnace increased gradually, which resulted in a decrease in fiber axial stress by up to 1950°C, where the fiber relaxed and the third stage ( T > 1950°C) began. The difference between expansion and shrinkage increased significantly, which increased fiber relaxation. Carbon fibers with fewer nitrogen atoms and more regular structures had a lower axial stress during high-temperature treatment, but the trend and characteristic temperature remained unchanged. The corresponding fiber high-temperature maximum stretching ratio and axial stress showed opposite trends below 1950°C. The ability to stretch the carbon fiber increased above 1950°C, which differed from the axial stress relaxation.

Impact of Environment Temperature Reduction on Force Performance of Steel Silos

2012 ◽  
Vol 204-208 ◽  
pp. 917-920
Author(s):  
Yue Dong Sun ◽  
Yan Pu Wang
Keyword(s):  
Axial Stress ◽  
Circumferential Stress ◽  
Stress Increase ◽  
Temperature Reduction ◽  
Environment Temperature ◽  
Cold Area ◽  
Steel Silos ◽  
The Impact

Based on the engineering case of a steel silo used for storage cement, the circumferential stress and axial stress of steel silo wall was carried out by ANSYS, when environment temperature falls. Result shows that the impact of environment temperature reduction on the silo wall circumferential stress is significant while the impact on axial stress is small. Circumferential stress increase about 21MPa and axial stress increase 4.1MPa when the environment temperature falls 10°C.The impact of temperature reduction should be taking into account in the design of steel silos in cold area.

Stress and Strain Distribution in Hypertensive and Normotensive Rat Aorta Considering Residual Strain

1996 ◽  
Vol 118 (1) ◽  
pp. 62-73 ◽  
Author(s):  
Takeo Matsumoto ◽  
Kozaburo Hayashi
Keyword(s):  
Residual Stresses ◽  
Wall Thickness ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Circumferential Direction ◽  
Wall Thickening ◽  
Left Renal Artery ◽  
Stress And Strain ◽  
Stress Distributions ◽  
Cross Sectional

The effects of hypertension on the stress and strain distributions through the wall thickness were studied in the rat thoracic aorta. Goldblatt hypertension was induced by constricting the left renal artery for 8 weeks. Static pressure-diameter-axial force relations were determined on excised tubular segments. The segments were then sliced into thin ring specimens. Circumferential strain distributions were determined from the cross-sectional shape of the ring specimens observed before and after releasing residual stresses by radial cutting. Stress distributions were calculated using a logarithmic type of strain energy density function. The wall thickness at the systolic blood pressure, Psys, significantly correlated with Psys. The mean stress and strain developed by Psys in the circumferential direction were not significantly different between the hypertensive and control aortas, while those in the axial direction were significantly smaller in the hypertensive aorta than in the control. The opening angles of the stress-free ring specimens correlated well with Psys. The stress concentration factor in the circumferential direction was almost constant and independent of Psys, although the stress distributions were not uniform through the wall thickness. Histological observation showed that the wall thickening caused by hypertension is mainly due to the hypertrophy of the lamellar units of the media, especially in the subintimal layer where the stress increase developed by hypertension is larger than in the other layers. These results indicate that: (a) the aortic wall adapts itself to the mechanical field by changing not only the wall dimensions but also the residual stresses, (b) this adaptation is primarily related to the circumferential stress but not to the axial stress, and (c) the aortic smooth muscle cells seem to change their morphology in response to the mechanical stress.

The Experimental Study and Mechanism Analysis on Flotation Separation of Tetradymite and Pyrite

2015 ◽  
Vol 1092-1093 ◽  
pp. 1490-1496
Author(s):  
Hai Liang Feng ◽  
Xiao Kui Che ◽  
Qi Zheng ◽  
Li Cheng Ma
Keyword(s):  
Experimental Study ◽  
Chemical Adsorption ◽  
Mechanism Analysis ◽  
Butyl Xanthate ◽  
Mineral Flotation ◽  
Ftir Spectral Analysis ◽  
The Common ◽  
The Difference ◽  
Adsorption Quantity ◽  
Dithiocarbamate Group

The experimental results of flotation of pure tetradymite and pyrite show that HL-1 is an efficient collector for tetradymite flotation. Comparing to the butyl xanthate, HL-1 has stronger collector ability and higher selectivity. It solves the common problem of the separation of tetradymite and pyrite. The difference of adsorption quantity is consistent with results of the single mineral flotation test. Through the measurements of adsorption, zeta-potential, and FTIR spectral analysis, the flotation mechanism of tetradymite with HL-1 has been discussed. It is concluded that the adsorption of HL-1 on tetradymite surface is chemical adsorption through the dithiocarbamate group of the collector chelating the Bi (III) of tetradymite to form metal complex.

Using MFL Corrosion Signals to Determine Biaxial Stress in Operating Pipelines

2000 ◽  
Author(s):  
Alfred E. Crouch
Keyword(s):  
Magnetic Flux ◽  
Internal Pressure ◽  
Pipe Wall ◽  
Axial Stress ◽  
Wall Stress ◽  
Biaxial Stress ◽  
Metal Loss ◽  
Pipe Surface ◽  
The Difference ◽  
Hoop Stresses

Previous work has shown that a corrosion assessment more accurate than B31.G or RSTRENG can be made if pipeline stresses are considered. A shell analysis can be carried out if both the corrosion profile and local pipe wall stresses are known. The corrosion profile can be approximated from analysis of magnetic flux leakage (MFL) signals acquired by an inline inspection tool (smart pig), but a measure of pipe wall stress has not been available. Approximations have been made based on pipe curvature, but a more direct measurement is desirable. Recent work has produced data that show a correlation between multi-level MFL signals from metal-loss defects and the stress in the pipe wall at the defect location. This paper presents the results of MFL scans of simulated corrosion defects in pipe specimens subjected to simultaneous internal pressure and four-point bending. MFL data were acquired at two different magnetic excitations using an internal scanner. The scanner’s sensor array measured axial, radial and circumferential magnetic flux components on the inner pipe surface adjacent to the defect. Comparison of the signals at high and low magnetization yields an estimate of the difference between axial and hoop stresses. If internal pressure is known, the hoop component can be determined, leaving data proportional to axial stress.

Experimental Investigation of Coke Drum Material Behavior Under Complex Thermal-Mechanical Loading

2011 ◽  
Author(s):  
Jie Chen ◽  
Zihui Xia
Keyword(s):  
Experimental Investigation ◽  
Mechanical Stress ◽  
Mechanical Loading ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Pressure Vessels ◽  
Material Behavior ◽  
Damage Mechanisms ◽  
Delayed Coking ◽  
Stress Cycling

Coke drums are vertical pressure vessels used in the delayed coking process in petroleum refineries and oil sands plants. Significant temperature variation during the delayed coking process causes damage in coke drums in the form of bulging and cracking. In order to better understand the damage mechanisms, an experimental investigation of coke drum material behavior under various thermal-mechanical loading conditions was performed. A thermal-mechanical material testing system is successfully designed and implemented. Six types of various thermal-mechanical cyclic tests were performed: 1. cyclic thermal loading under constant uniaxial stress; 2. in-phase thermal and mechanical stress cycling; 3. out-of-phase thermal and mechanical stress cycling; 4. fully-reversed uniaxial cyclic loading with in-phase thermal cycling; 5. in-phase thermal-axial stress cycling with constant circumferential stress; 6. in-phase thermal-axial stress cycling with mean stress. Some of theses tests are similar to the actual loading scenario experienced by the coke drums. The experimental findings lead to better understanding of the damage mechanisms occurring in coke drums such as bulging.

The Mechanics of the Flame Bending Process: Theory and Applications

1987 ◽  
Vol 31 (04) ◽  
pp. 269-281
Author(s):  
Amiram Moshaiov ◽  
William S. Vorus
Keyword(s):  
Solution Technique ◽  
Plastic Behavior ◽  
Plate Bending ◽  
Elastic Plastic ◽  
The Past ◽  
Bending Process ◽  
Analytical Research ◽  
Beam Bending ◽  
The Difference ◽  
Future Work

The flame bending process can be most useful in the present effort to automate the plate bending process in shipyards. To achieve this goal, the complicated thermo-elastic-plastic behavior of the plate during the process must be understood. A review of the past analytical research efforts reveals that these attempts have been restricted to beam bending. Here a theory for the thermo-elastic-plastic plate bending is developed. Furthermore, using a boundary element method as a solution technique, the difference between the mechanics of beam bending versus plate bending is shown. Recommendations for future work are given.

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