Numerical Analysis of Temperature Fields and Thermal Stress Fields in Heating Process of Large-Diameter Seamless Steel Pipe Blanks

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Feng Liu ◽  
Shuai Yang ◽  
Yao Xiao ◽  
Yi Han ◽  
Enlin Yu ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Temperature Difference ◽  
Large Diameter ◽  
Pipe Blank ◽  
Temperature Fields ◽  
Stress Fields ◽  
Heating Process ◽  
Furnace Temperature ◽  
Pipe Blanks ◽  
Seamless Steel

Abstract In the piercing process of large-diameter seamless steel pipe blanks after heating, severe lateral cracks easily occur on the surface of pierced pipe blanks owing to the effects of the large temperature difference and thermal stress during the heating phase, influencing the finished product ratio and the safety and stability of use. Therefore, obtaining pipe blanks with uniform temperature distributions and low thermal stress peaks is the basis for the quality assurance of seamless pipes. In this paper, a study was conducted with large-diameter TP321 seamless pipe blanks with an example. The heating process of the pipe blank was investigated from two perspectives, temperature fields and thermal stress fields. Moreover, the effects of heating rate, initial furnace temperature, and hot-charging temperature were quantitatively analyzed. It was found that the peaks of the temperature difference and thermal stress both occurred at the early stage of heating. The temperature field and thermal stress distribution of the pipe blank gradually changed during heating. At the initial stage of heating, the temperature at the outer diameter edge was the highest, and the maximum thermal stress zones were concentrated on the inner hole edge and external surface. At the late stage of heating, the highest temperature zone and the maximum thermal stress zone were both focused on the inner hole surface. Lower initial furnace temperature and higher hot-charging temperature were more conducive to decreasing the maximum temperature difference and peak thermal stress, while the changes in heating rate had insignificant effects.

Numerical Simulation of Fracture Process of Concrete Dam due to Freezing and Thawing with Finite Element Method

2007 ◽  
Vol 348-349 ◽  
pp. 941-944
Author(s):  
Li Juan Cao ◽  
Shou Ju Li ◽  
Zi Chang Shangguan
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Cold Climate ◽  
Temperature Fields ◽  
Stress Fields ◽  
Freezing And Thawing ◽  
Concrete Dam ◽  
Element Method

Freezing and thawing damage is one of the major problems of concrete dams in cold climate. Cracking and splitting are the most common results of freezing and thawing deterioration in concrete dam. The cracking problem owing to freezing and thawing was investigated by making sue of finite element methods. The interpretation of the mechanism of failure was also given. In order to compute the thermal stress fields of concrete dam caused by freezing and thawing, the temperature changes versus seasons is determined according to measured data. The temperature fields of concrete dam versus seasons are simulated by using finite element method. Basing on the computational results of the temperature fields of concrete dam, the thermal stress fields are calculated numerically. The researches show that the first principal stress of concrete dam at downstream surface can exceed the tensile strength of concrete material. The numerical simulation results of fractured regions of concrete dam agreed with practical observed data.

Numerical Analysis on Cooling Process of Monocrystal Silicon Rod Manufactured with Czochralski Method

2012 ◽  
Vol 217-219 ◽  
pp. 1425-1428 ◽  
Author(s):  
Xiao Xia Liu ◽  
Li Jun He ◽  
Rui Zhou ◽  
Shao Lin Ma ◽  
Jing Mao
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Numerical Analysis ◽  
Czochralski Method ◽  
Temperature Fields ◽  
Stress Fields ◽  
Finite Element Code ◽  
Cooling Process ◽  
Thermally Induced ◽  
Thermal Stress Field

A numerical analysis was performed to investigate the temperature distribution and thermal stress field in monocrystal silicon rod in the cooling process of manufactured with Czochralski (CZ) method. The thermally-induced residual stress fields of silicon rod under different length of cool-down time conditions were obtained as well as temperature fields, respectively. All simulations were finished by using ANSYS finite element code. It showed that, maximum thermal stress was mainly appeared on rod surface, the influence of length of cool-down time on it was not remarkable, the magnitude of it was far below the critical strength of silicon throughout.

Thermal Stress Field Simualtion Research in Heating Process Based on FEM

2011 ◽  
Vol 361-363 ◽  
pp. 840-843
Author(s):  
Zhao Wei Dong ◽  
Xiao Hang Wan ◽  
Jie Ying Zhang
Keyword(s):  
Thermal Stress ◽  
Stress Field ◽  
Specific Heat ◽  
Heating Rate ◽  
Heating Process ◽  
Furnace Temperature ◽  
Heat Efficiency ◽  
Analysis Theory ◽  
Thermal Stress Field ◽  
Heating Model

For increasing heat efficiency and preventing crack resulting in thermal stress, the laws of heating slab must be accurately studied. The thermal stress field distribution in slab heating process is researched, which adopts FEM and bases on the transient non-linear heat analysis theory. The 3500 slab heating model is established in according to the heating technique in mills. The factor of conduction coefficient and specific heat changing with temperature also are considered. The heating process is simulated and the influence laws of furnace temperature and heating rate are drawn, which is very significant in engineering.

Research on Life Assessment and Monitoring System of Steam Turbine

2005 ◽  
Author(s):  
Qing He ◽  
Dongmei Du
Keyword(s):  
Thermal Stress ◽  
Stress Field ◽  
Steam Turbine ◽  
Monitoring System ◽  
Thermal Strain ◽  
Life Assessment ◽  
Temperature Fields ◽  
Stress Fields ◽  
Load Change ◽  
Assessment And Monitoring

Since steam turbine always operates at high temperature and pressure, life of the key components of steam turbine, such as, rotor, cylinder, bolt etc., must be considered. Furthermore, the involvement of large-scale steam turbine set in load adjustment makes the life assessment of those key components more important, which are main objects of life assessment and monitoring of steam turbine. Steam turbine suffers very large thermal stress and strain while startup, slowdown and load change, therefore, thermal stress is one of the significant monitoring parameters. Stress field is an important and full-distributed graphics. The 2-D discrete models and its finite element models of rotor and cylinder of steam turbine are analyzed in this paper. Taking rotor and cylinder as control objects; the boundary conditions are given, so that the temperature fields, thermal stress field and thermal strain, etc. are solved. Consequently, a life assessment and online monitoring system of steam turbine is developed, in which the temperature fields and stress fields of rotors and cylinders of high pressure (HP) and intermediate pressure (IP) of steam turbine are calculated and displayed on-line. In accordance with the stress fields, the life wastages caused by the operations, such as, start-up or slowdown or load change, etc., are calculated. The life remainder is the foundation of decision making of management and control of steam turbine operation, maintenance, safety etc.

Simulation of vibration piercing of pipe blank at press

2020 ◽  
Vol 76 (11) ◽  
pp. 1128-1138
Author(s):  
S. R. Rakhmanov
Keyword(s):  
High Frequency ◽  
Deformation Zone ◽  
Pipe Blank ◽  
Equipment Operation ◽  
Metal Deformation ◽  
Technological Tool ◽  
High Frequency Vibrations ◽  
Pipe Blanks ◽  
Wave Phenomena

In some cases, the processes of piercing or expanding pipe blanks involve the use of high-frequency active vibrations. However, due to insufficient knowledge, these processes are not widely used in the practice of seamless pipes production. In particular, the problems of increasing the efficiency of the processes of piercing or expanding a pipe blank at a piercing press using high-frequency vibrations are being solved without proper research and, as a rule, by experiments. The elaboration of modern technological processes for the production of seamless pipes using high-frequency vibrations is directly related to the choice of rational modes of metal deformation and the prediction resistance indicators of technological tools and the reliability of equipment operation. The creation of a mathematical model of the process of vibrating piercing (expansion) of an axisymmetric pipe blank at a piercing press of a pipe press facility is an actual task. A calculation scheme for the process of piercing a pipe plank has been elaborated. A dependence was obtained characterizing the speed of front of plastic deformation propagation on the speed of penetration of a vibrated axisymmetric mandrel into the pipe workpiece being pierced. The dynamic characteristics of the occurrence of wave phenomena in the metal being pierced under the influence of a vibrated tool have been determined, which significantly complements the previously known ideas about the stress-strain state of the metal in the deformation zone. The deformation fields in the zones of the disturbed region of the deformation zone were established, taking into account the high-frequency vibrations of the technological tool. It has been established that the choice of rational parameters (amplitude-frequency characteristics) of the vibration piercing process of a pipe blank results in significant increase in the efficiency of the process, the durability of the technological tool and the quality of the pierced blanks.

Die Forging Process Simulation of a Connecting Rod

2011 ◽  
Vol 704-705 ◽  
pp. 302-307
Author(s):  
Lei Xu ◽  
Guang Ze Dai ◽  
Xing Ming Huang ◽  
Jing Han ◽  
Jun Wen Zhao
Keyword(s):  
Reduction Rate ◽  
Temperature Fields ◽  
Stress Fields ◽  
Connecting Rod ◽  
Preheat Temperature ◽  
Forging Process ◽  
Optimum Parameters ◽  
Die Forging ◽  
High Level ◽  
Deform 3D

Numerical simulation of connecting rod die forging processing was performed by finite element method (FEM) software Deform 3D. The changes of the temperature fields, stress fields of the billet and dies, and upper setting force-stroke curve during the die forging were obtained. The simulation results show that (1) the increase of the fillet radius of dies could effectively reduce the stress concentration so that to prevent the die crack arising at high level stress; (2) the optimum parameters of die forging process are 430°C for forging temperature, 200°C for preheat temperature of dies and 80mm/s for reduction rate by comparing both fields of the stress and temperature during different forging process..

Analysis of the Thermal Stress at the Tubesheet in Floating-Head or U-Tube Heat Exchangers

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Jiuyi Liu ◽  
Caifu Qian ◽  
Huifang Li
Keyword(s):  
Thermal Stress ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Influence Factors ◽  
Area Ratio ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Numerical Tests ◽  
Hole Area

Thermal stress is an important factor influencing the strength of a heat exchanger tubesheet. Some studies have indicated that, even in floating-head or U-tube heat exchangers, the thermal stress at the tubesheet is significant in magnitude. For exploring the value, distribution, and the influence factors of the thermal stress at the tubesheet of these kind heat exchangers, a tubesheet and triangle arranged tubes with the tube diameter of 25 mm were numerically analyzed. Specifically, the thermal stress at the tubesheet center is concentrated and analyzed with changing different parameters of the tubesheet, such as the temperature difference between tube-side and shell-side fluids, tubesheet diameter, thickness, and the tube-hole area ratio. It is found that the thermal stress of the tubesheet of floating-head or U-tube heat exchanger was comparable in magnitude with that produced by pressures, and the distribution of the thermal stress depends on the tube-hole area and the temperature inside the tubes. The thermal stress at the center of the tubesheet surface is high when tube-hole area ratio is very low. And with increasing the tube-hole area ratio, the stress first decreases rapidly and then increases linearly. A formula was numerically fitted for calculating the thermal stress at the tubesheet surface center which may be useful for the strength design of the tubesheet of floating-head or U-tube heat exchangers when considering the thermal stress. Numerical tests show that the fitted formula can meet the accuracy requirements for engineering applications.

Numerical Analysis of Flow Fields and Temperature Fields in a Regenerative Heating Furnace for Steel Pipes

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Yi Han ◽  
Feng Liu ◽  
Xin Ran
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Flow Velocity ◽  
Gas Flow ◽  
Flow Fields ◽  
Heating Furnace ◽  
Temperature Fields ◽  
Turbulent Layer ◽  
Steel Pipes ◽  
Pipe Blanks

In the production process of large-diameter seamless steel pipes, the blank heating quality before roll piercing has an important effect on whether subsequently conforming piping is produced. Obtaining accurate pipe blank heating temperature fields is the basis for establishing and optimizing a seamless pipe heating schedule. In this paper, the thermal process in a regenerative heating furnace was studied using fluent software, and the distribution laws of the flow field in the furnace and of the temperature field around the pipe blanks were obtained and verified experimentally. The heating furnace for pipe blanks was analyzed from multiple perspectives, including overall flow field, flow fields at different cross sections, and overall temperature field. It was found that the changeover process of the regenerative heating furnace caused the temperature in the upper part of the furnace to fluctuate. Under the pipe blanks, the gas flow was relatively thin, and the flow velocity was relatively low, facilitating the formation of a viscous turbulent layer and thereby inhibiting heat exchange around the pipe blanks. The mutual interference between the gas flow from burners and the return gas from the furnace tail flue led to different flow velocity directions at different positions, and such interference was relatively evident in the middle part of the furnace. A temperature “layering” phenomenon occurred between the upper and lower parts of the pipe blanks. The study in this paper has some significant usefulness for in-depth exploration of the characteristics of regenerative heating furnaces for steel pipes.

Thermal stress inhibition in double crucible Czochralski large diameter crystal growth

2005 ◽  
Vol 274 (1-2) ◽  
pp. 307-316 ◽  
Author(s):  
O.A. Louchev ◽  
S. Kumaragurubaran ◽  
S. Takekawa ◽  
K. Kitamura
Keyword(s):  
Thermal Stress ◽  
Crystal Growth ◽  
Large Diameter ◽  
Double Crucible
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