Three-Dimensional Numerical Analysis for Bolted Flange Joints Considering Effect of Creep

2018 ◽  
Author(s):  
Lewen Bi ◽  
Lanzhu Zhang
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Numerical Analysis ◽  
Yield Strength ◽  
Room Temperature ◽  
Three Dimensional ◽  
Short Term ◽  
Flange Connection ◽  
Petroleum Chemical ◽  
Bolted Flange

Bolted flange joints are widely used in petroleum, chemical, nuclear and power industries, etc. With more and more devices are used at high temperature, the performance of flange connections becomes more complex, especially with creep of different components in flange connection. At elevated temperature, with the loss of bolt force and gasket force due to creep, the joints are prone to leak. Based on this, this paper analyzed the relaxation of bolt force at elevated temperature due to creep of bolt, flange and gasket separately and simultaneously. Besides, the influence of different initial installation stress of bolts was also studied. The results showed bolted flange joints relaxed due to gasket creep during early short term service. However, contribution of bolt and flange creep became more and more significant with the extension of time. With considering the creep of bolt, flange and gasket simultaneously, 50% to 60% of the bolt material yield strength at room temperature was recommended as the bolt initial installation stress for the joint case studied in this paper.

scholarly journals Microstructure and Tensile Properties of Graphene-Oxide-Reinforced High-Temperature Titanium-Alloy-Matrix Composites

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3358 ◽  
Author(s):  
Hang Chen ◽  
Guangbao Mi ◽  
Peijie Li ◽  
Xu Huang ◽  
Chunxiao Cao
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
Graphene Oxide ◽  
High Temperature ◽  
Yield Strength ◽  
Room Temperature ◽  
Second Phase ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
The Matrix

In this study, graphene-oxide (GO)-reinforced Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium-alloy-matrix composites were fabricated by powder metallurgy. The mixed powders with well-dispersed GO sheets were obtained by temperature-controlled solution mixing, in which GO sheets adsorb on the surface of titanium alloy particles. Vacuum deoxygenating was applied to remove the oxygen-containing groups in GO, in order to reduce the introduction of oxygen. The compact composites with refined equiaxed and lamellar α phase structures were prepared by hot isostatic pressing (HIP). The results show that in-situ TiC layers form on the surface of GO and GO promotes the precipitation of hexagonal (TiZr)6Si3 particles. The composites exhibit significant improvement in strength and microhardness. The room-temperature tensile strength, yield strength and microhardness of the composite added with 0.3 wt% GO are 9%, 15% and 27% higher than the matrix titanium alloy without GO, respectively, and the tensile strength and yield strength at 600 °C are 3% and 21% higher than the matrix alloy. The quantitative analysis indicates that the main strengthening mechanisms are load transfer strengthening, grain refinement and (TiZr)6Si3 second phase strengthening, which accounted for 48%, 30% and 16% of the improvement of room-temperature yield strength, respectively.

Effect of High Temperature Caliber Rolling on Microstructure and Room Temperature Tensile Properties of Mg-3Al-1Zn (AZ31) Alloy

2013 ◽  
Vol 209 ◽  
pp. 6-9 ◽  
Author(s):  
Rajendra Doiphode ◽  
S.V.S. Narayana Murty ◽  
Nityanand Prabhu ◽  
Bhagwati Prasad Kashyap
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Yield Strength ◽  
Strain Rate ◽  
Tensile Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Az31 Alloy ◽  
Rolling Temperature ◽  
Grain Sizes

Mg-3Al-1Zn (AZ31) alloy was caliber rolled at 250, 300, 350, 400 and 450 °C. The effects of caliber rolling temperature on the microstructure and tensile properties were investigated. The room temperature tensile tests were carried out to failure at a strain rate of 1 x 10-4s-1. The nature of stress-strain curves obtained was found to vary with the temperature employed in caliber rolling. The yield strength and tensile strength followed a sinusoidal behaviour with increasing caliber rolling temperature but no such trend was noted in ductility. These variations in tensile properties were explained by the varying grain sizes obtained as a function of caliber rolling temperature.

Shape stability of chosen thin wood based panels after heating

2019 ◽  
Vol 106 ◽  
pp. 85-89
Author(s):  
MACIEJ SYDOR ◽  
Bartosz Pałubicki
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Thin Plate ◽  
Dimensional Stability ◽  
Power Supplies ◽  
Short Term ◽  
Shape Stability ◽  
Short Term Exposure ◽  
The Impact

Shape stability of chosen thin wood based panels after heating. Lignocellulose board materials are commonly used for furniture construction. Typically, these are particle boards, fibreboard or plywood with thicknesses from 10 to 20 mm, however, some furniture elements are made of thin boards with a thickness of 3-4 mm (back walls, bottoms of drawers and others). Modern furniture uses built-in components that are a source of heat, such as lamps, power supplies, ovens. Local high temperature may negatively affect the shape stability of thin lignocellulose plates. The aim of the research described in this article was to determine the impact of shortterm exposure to high temperature on the dimensional stability of selected thin plate furniture materials. Four different HDF boards with nominal thicknesses of 3 mm and four different plywood boards with nominal thicknesses of 2 to 4 mm were tested. The test samples were subjected to a short-term exposure to temperatures of up to 250°C. As a result of the tests, it was found that HDF boards are characterized by a much higher shape stability at elevated temperature than boards made of plywood.

Deformation of an extruded nickel beryllide between room temperature and 820 °C

1991 ◽  
Vol 6 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
G.M. Pharr ◽  
S.V. Courington ◽  
J. Wadsworth ◽  
T.G. Nieh
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Strain Hardening ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Tension And Compression ◽  
Better Than

The mechanical properties of nickel beryllide, NiBe, have been investigated in the temperature range 20–820 °C. The room temperature properties were studied using tension, bending, and compression tests, while the elevated temperature properties were characterized in compression only. NiBe exhibits some ductility at room temperature; the strains to failure in tension and compression are 1.3% and 13%, respectively. Fracture is controlled primarily by the cohesive strength of grain boundaries. At high temperatures, NiBe is readily deformable—strains in excess of 30% can be achieved at temperatures as low as 400 °C. Strain hardening rates are high, and the flow stress decreases monotonically with temperature. The high temperature strength of NiBe is as good or better than that of NiAl, but not quite as good as CoAl.

Effect of Gasket Compression Resilience on the Tightness of Bolted Flange System

2016 ◽  
Vol 853 ◽  
pp. 328-334
Author(s):  
Xiao Tao Zheng ◽  
Jia Lin Zi Pan ◽  
Jiu Yang Yu
Keyword(s):  
Room Temperature ◽  
Design Calculation ◽  
Compression Force ◽  
Working Pressure ◽  
Flange Connection ◽  
Connection System ◽  
Gasket Material ◽  
Bolted Flange ◽  
Nonlinear Performance ◽  
Flange Angle

Gasket is an important sealing element of bolted flange connection structure. The nonlinear performance of the gasket material will make the flange angle and gasket compression force change. Therefore, it plays an important role in the tightness of bolted flange connection system. Apart from acknowledgment of this effect, there exists no established design calculation procedure that accounts for tightness. In this paper, the mechanical properties of the gasket at room temperature were studied, it is known that the rebound performance of the gasket is related to the initial preload. And the effect of the compressive resilience of the gasket on the tightness of the bolt flange system was discussed. The tightness of the bolt flange system can be achieved by adjusting the initial preload and working pressure of the gasket, it provides the basis for design and evaluate the tightness of bolted flange connection system.

Visco-Elastic FEM Stress Analysis of Bolted Flange Connections With PTFE-Blended Gaskets Under Elevated Temperature

2012 ◽  
Author(s):  
Koji Sato ◽  
Shinya Kurokawa ◽  
Toshiyuki Sawa
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Fluid Temperature ◽  
Long Term Conditions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Strain Relationship ◽  
Bolted Flange ◽  
Relationship Of

Bolted flange connections with gaskets have been used under high temperature and long-term conditions. Sometimes leakage accidents occur from the gasket interfaces due to the creep and relaxation phenomena. In the present paper, the changes of the gasket stress in bolted flange connections under high temperature conditions for a long-term are analyzed using FEM calculations taking into account the gasket temperature dependency. The gaskets used are PTFE-blended (V#GF300). It’s shown that the effect of the temperature on the stress-strain relationship of the gasket is substantial. The changes in the gasket stress of the connections for 12 months are analyzed using the FEM. The effects of nominal diameter of flanges, retightening and the fluid temperature (20 to 300 °C) on the change of gasket stress in the connections under elevated temperature are examined using the FEM calculations. It is found that the reduction in the gasket stress is over 40%. In addition, experiments to measure the axial bolt force were carried out. The calculated results are in a fairly good agreement with the experimental results. The results reveal that the long-term behavior of the bolted flange connections can be estimated in our study. Discussion is made on the effects of the bolt preload and retightening on the reduction of the gasket stress and the sealing performance.

300C Capable Digital Integrated Circuits in SiC Technology

2012 ◽  
Vol 717-720 ◽  
pp. 1261-1264 ◽  
Author(s):  
Amita Patil ◽  
Naresh Rao ◽  
Vinayak Tilak
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Elevated Temperature ◽  
Integrated Circuits ◽  
Room Temperature ◽  
Continuous Operation ◽  
Shift Register ◽  
Digital Integrated Circuits ◽  
Enhancement Mode

This paper pertains to development of high temperature capable digital integrated circuits in n-channel, enhancement-mode Silicon Carbide (SiC) MOS technology. Among the circuits developed in this work are data latch, flip flops, 4-bit shift register and ripple counter. All circuits are functional from room temperature up to 300C without any notable degradation in performance at elevated temperature. The 4-bit counter demonstrated stable behavior for over 500 hours of continuous operation at 300C.

Numerical Analysis of Three-Dimensional Flow in an Industry-Size Hydrothermal Autoclave Subjected to Non-Uniform Heating

2002 ◽  
Author(s):  
Hongmin Li ◽  
Guo-Xiang Wang ◽  
Edward A. Evans
Keyword(s):  
High Temperature ◽  
Numerical Analysis ◽  
Three Dimensional ◽  
Hydrothermal Growth ◽  
Chamber Wall ◽  
Heating Condition ◽  
Uniform Heating ◽  
Three Dimensional Flow ◽  
Growth Environment ◽  
Dimensional Flow

Hydrothermal growth is an important industrial process to produce piezoelectric crystals such as quartz. It takes place in a cylindrical container called an autoclave, which is filled with aqueous solution at a high temperature and a high pressure. The high temperature growth condition is maintained through electrical resistors on the outer surface of an autoclave. In practice there is a non-uniform heating condition in the circumferential direction. Many theoretical and numerical studies, however, assume an axisymmetric heating condition. This paper presents a numerical analysis of the three-dimensional heat transfer and fluid flow in hydrothermal growth due to such non-uniform heating. The analysis is based on an industry-size autoclave with an aspect ratio of 10. The non-uniform heating is introduced on the surface of both the lower dissolving chamber and the upper growing chamber of an autoclave with and without a baffle at the middle height. The flow and isotherm patterns were obtained with the temperature difference between the two chambers kept at 10 °C. The circumferentially non-uniform temperature has dramatic effects on the three-dimensional flow and therefore the temperature distribution in the autoclave. When the dissolving chamber is subjected to circumferentially non-uniform heating, a baffle is essential to create a uniform growth environment in the growing chamber. To obtain high quality single crystals, however, the temperature control on the growing chamber wall is more important than that on the dissolving chamber wall.

Elevated Temperature Tensile Behavior of Nextel™ 720 Fibers

Materials ◽  
2003 ◽  
Author(s):  
D. M. Pai ◽  
S. N. Yarmolenko ◽  
E. Freeman ◽  
L. P. Zawada
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Thermal Exposure ◽  
Strength Distribution ◽  
Tensile Behavior ◽  
Beneficial Effects ◽  
Elevated Temperature Tensile ◽  
Long Duration ◽  
Temperature Exposure

The tensile behavior of Nextel 720 fibers at elevated temperature was compared with room temperature results for both bare and monazite-coated fibers. While coated and uncoated fibers have nearly identical tensile strengths and Weibull moduli at room temperature, differences in response were seen at elevated temperature. Coated fibers tested at 1200°C were found to have a 40% drop in strength. Uncoated fibers at high temperature exhibited 55% less strength than at room temperature. However, the tensile strength distribution for uncoated fibers tested at high temperature exhibited two distinct populations, indicating two different failure mechanisms. One population showed a 50% drop while the other showed a 64% drop. The coating was thus found to have a protective effect in terms of short-duration high-temperature exposure. Further, the effect of soaking on strength was investigated by thermally soaking coated and uncoated fibers in air at 1200°C for 100 hours prior to tensile testing at elevated temperature. In this case, the long duration of thermal exposure appeared to eliminate the beneficial effects of the coating. Soaked fibers, both coated and uncoated, were found to have nearly identical strengths at 1200°C—a reduction of about 60%.

scholarly journals Numerical Analysis of Flow Behavior in Vortex Tube for Different Gases

2017 ◽  
Vol 7 (2) ◽  
pp. 18
Author(s):  
Kiran Dattatraya Devade ◽  
Ashok T. Pise ◽  
Atul R. Urade
Keyword(s):  
High Temperature ◽  
Numerical Analysis ◽  
Vortex Tube ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Energy Separation ◽  
Separation Device ◽  
Compressed Gas ◽  
Turbulent Models ◽  
Different Gases

The vortex tube is an energy separation device that separates compressed gas stream into a low and a high temperature stream. Present work reports the flow behavior inside the vortex tube for different commonly used fluids with varied properties like Air, He, N2, CO2 and NH3. Flow behavior investigation for three-dimensional short straight-diverging vortex tube is done with CFD code (ANSYS 16.0). Different turbulent models, standard k-epsilon, Realizable k-epsilon and RNG k-epsilon are tested. Realizable k-epsilon model was then used for analysis. Flow behavior of gases with varied multi-atomic number is analyzed and compared with literature. The effect on temperature for N2 is found to be better, followed by He, CO2, Air and NH3. Energy separation for N2 is 46 % higher than all other gases. Energy separation and flow behavior inside vortex tube is analyzed and compared with literature.

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