Bowing of Cryogenic Pipelines

1961 ◽  
Vol 28 (3) ◽  
pp. 409-416 ◽  
Author(s):  
W. G. Flieder ◽  
J. C. Loria ◽  
W. J. Smith
Keyword(s):  
Thermal Stress ◽  
Thermal Stresses ◽  
Temperature Gradients ◽  
Stress Distributions ◽  
Flow Conditions ◽  
Additional Consideration ◽  
Dead Weight ◽  
Circular Arc ◽  
Cryogenic Fluids

The design of propellant loading systems for present-day missiles involves the design of pipelines that can carry cryogenic fluids and requires an additional consideration beyond the conventional analyses for flexibility and dead weight. Because of varying flow conditions and boil-off, these cryogenic lines experience varying fill levels and concomitant temperature gradients which cause these lines to bow; i.e., to assume a uniform curvature of circular arc. If constrained, the thermal-stress distributions which are generated by the temperature gradients will have superposed on them additional stresses, which result from the action of the support constraints. This combination of stresses may be critical and/or the loads on the supports may be excessive. The following analysis investigates these bowing effects, thermal stresses, and indicates the support problems entailed.

scholarly journals Thermal Stresses in Porous Materials under Thermal Shock by Cooling Medium-Infiltration Effect on Thermal Stress Distributions-

2004 ◽  
Vol 112 (1303) ◽  
pp. 172-178 ◽  
Author(s):  
Hiroaki TANAKA ◽  
Yuji MAKI ◽  
Kazuki TSUBOI ◽  
Sawao HONDA ◽  
Tadahiro NISHIKAWA ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Porous Materials ◽  
Thermal Shock ◽  
Thermal Stresses ◽  
Stress Distributions ◽  
Cooling Medium

Thermal Fatigue Evaluation Method Based on Power Spectrum Density Functions Against Fluid Temperature Fluctuation

2005 ◽  
Author(s):  
Naoto Kasahara ◽  
Nobuyuki Kimura ◽  
Hideki Kamide
Keyword(s):  
Thermal Stress ◽  
Power Spectrum ◽  
High Frequency ◽  
Thermal Stresses ◽  
Evaluation Method ◽  
Power Spectrum Density ◽  
Temperature Gradients ◽  
Fluid Temperature ◽  
Spectrum Density ◽  
Fatigue Evaluation

Fluid temperature fluctuates at an incomplete mixing area of high and low temperature fluids in nuclear components. It induces random variations of local temperature gradients in structural walls, which lead to cyclic thermal stresses. When thermal stresses and cycle numbers are large, there are possibilities of fatigue crack initiations and propagations. It is recognized that there are attenuation factors depending on fluctuation frequency in the transfer process from fluid temperature to thermal stresses. If a frequency of fluctuation is very low, whole temperature of the wall can respond to fluid temperature, because thermal diffusivity homogenizes structural temperature. Therefore, low frequency fluctuations do not induce large thermal stress due to temperature gradients in structures. On the other hand, a wall surface cannot respond to very high frequency fluctuation, since a structure has a time constant of thermal response. High frequency fluctuations do not lead to large thermal stress. Paying attention to its attenuation mechanism, Japan Nuclear Cycle Development Institute (JNC) has proposed a fatigue evaluation method related to frequencies. The first step of this method is an evaluation of Power Spectrum Density (PSD) on fluid, from design specifications such as flow rates, diameters of pipes and materials. In the next step, the PSD of fluid is converted to PSD of thermal stress by the frequency transfer function. Finally, the PSD of thermal stress is transformed to time history of stress under an assumption of random phase. Fatigue damage factors can be evaluated from stress ranges and cycles obtained by the rain flow wave count method. Proposed method was applied to evaluate fatigue damage of piping junction model tests conducted at Oarai Engineering Center. Through comparison with direct evaluation from measurements and predictions by conventional methods, the accuracy of the proposed method was validated.

scholarly journals A Novel MDD-Based BEM Model for Transient 3T Nonlinear Thermal Stresses in FGA Smart Structures

2020 ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Thermal Stress ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Smart Structures ◽  
Industrial Applications ◽  
Functionally Graded ◽  
Numerical Results ◽  
Stress Distributions ◽  
Proposed Model ◽  
Further Development

The main objective of this chapter is to introduce a novel memory-dependent derivative (MDD) model based on the boundary element method (BEM) for solving transient three-temperature (3T) nonlinear thermal stress problems in functionally graded anisotropic (FGA) smart structures. The governing equations of the considered study are nonlinear and very difficult if not impossible to solve analytically. Therefore, we develop a new boundary element scheme for solving such equations. The numerical results are presented highlighting the effects of the MDD on the temperatures and nonlinear thermal stress distributions and also the effect of anisotropy on the nonlinear thermal stress distributions in FGA smart structures. The numerical results also verify the validity and accuracy of the proposed methodology. The computing performance of the proposed model has been performed using communication-avoiding Arnoldi procedure. We can conclude that the results of this chapter contribute to increase our understanding on the FGA smart structures. Consequently, the results also contribute to the further development of technological and industrial applications of FGA smart structures of various characteristics.

Quasi-static thermal stresses due to a concentrated moving heat source in a thin plate

2016 ◽  
Vol 22 (2) ◽  
pp. 243-256
Author(s):  
Amir Reza Shahani ◽  
Samad Kalani
Keyword(s):  
Thermal Stress ◽  
Stress Field ◽  
Heat Source ◽  
Thin Plate ◽  
Thermal Stresses ◽  
Static Solution ◽  
Stress Distributions ◽  
Moving Heat Source ◽  
Displacement Potential ◽  
Thermal Stress Field

Temperature and thermal stress distributions in a two-dimensional infinite thin plate subjected to a moving heat source with variable power and velocity are obtained by solving quasi-static thermoelasticity equations analytically with the aid of a thermoelastic displacement potential. The results show good agreement with experimental data for a stationary source with constant power and with a steady-state analytical solution in the open literature. It is shown that the quasi-static solution can predict changes of the thermal stress field during the movement of the heat source, and can give the effect of changes of power and velocity of the heat source on the thermal stress field during its movement.

Unsteady thermal stress analysis in three-dimensional problems by means of the thermoelastic displacement potential and the boundary element method

1990 ◽  
Vol 25 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Y Ochiai ◽  
R Ishida ◽  
T Sekiya
Keyword(s):  
Thermal Stress ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Stress Distributions ◽  
Displacement Potential ◽  
Thermal Displacements ◽  
Thermoelastic Displacement ◽  
Element Method

A numerical method to analyse unsteady thermal stresses in three-dimensional problems is proposed. It is shown that three-dimensional unsteady thermal stress problems can be easily solved without the volume integral by means of the thermoelastic displacement potential and the boundary element method. It is also shown that the time integral can be easily carried out analytically. In order to investigate the accuracy of this method, unsteady thermal stress distributions for a sphere and a circular cylinder are obtained. As a numerical example for which it is difficult to obtain the analytical solution, thermal displacements and surface stress distributions for a torus are obtained.

Reducing Thermal Stress in Turbine Cylinders Subjected to Cyclic Service

1962 ◽  
Vol 84 (4) ◽  
pp. 389-402 ◽  
Author(s):  
Walter Sinton ◽  
R. E. Warner
Keyword(s):  
Thermal Stress ◽  
Thermal Stresses ◽  
Current Problem ◽  
Temperature Gradients ◽  
Inlet Temperature ◽  
Steam Turbines ◽  
Cyclic Service ◽  
And Control

The current problem of cracked cylinders encountered on steam turbines subjected to cyclic service points up the need for a better understanding of the thermal stresses which cause the difficulty, and for techniques to minimize and control these stresses. This paper establishes an improved approach to operation based on applying instrumentation to monitor and limit temperature gradients to recommended values. Benefits of heating manifolds are discussed. The advantage inherent in flexible inlet features has been incorporated into current cylinder designs for units operating in the range of 850 to 950 F inlet temperature.

Thermal Stress Simulation of the Surface Grinding

2011 ◽  
Vol 383-390 ◽  
pp. 2211-2215
Author(s):  
Chong Lue Hua ◽  
Gui Cheng Wang ◽  
Hong Jie Pei ◽  
Gang Liu
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Surface Grinding ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Temperature Dependent ◽  
Finite Element Procedure ◽  
Temperature Dependent Properties ◽  
Stress Simulation

Thermal stresses of grinding plays an important role on the fatigue and wear resistance of the component. A comprehensive analysis of thermal stress induced by surface grinding has been conducted with aid of the finite element method. To obtain a reliable figure of thermal stress induced by grinding, temperature-dependent properties of workpiece materials were taken into account. The developed finite element procedure has also been applied to calculate the surface and sub-surface thermal stress induced by moving source of triangular heat when convection and radiation is occurred over the whole work. Based on an analysis of the effects of wheel velocity on the thermal stress distributions in an elastic-plastic solid, some important conclusions were given.

Thermal Stresses in a ZrO2/FGM/Ti-6Al-4V Composite ECBC Plate with Temperature-Dependent Material Properties

2010 ◽  
Vol 150-151 ◽  
pp. 873-876
Author(s):  
Dai Hui Tu ◽  
Yang Jian Xu ◽  
Jian Hui Jia
Keyword(s):  
Thermal Stress ◽  
Compressive Stress ◽  
Material Properties ◽  
Composite Plate ◽  
Thermal Stresses ◽  
Ceramic Surface ◽  
Stress Distributions ◽  
Temperature Dependent ◽  
Maximum Compressive Stress ◽  
Gradient Layer

The steady thermal stress distributions and effect factors in a ZrO2/FGM/Ti-6Al-4V composite ECBC plate with temperature-dependent material properties under convective heat transfer boundary were investigated by the NFEM and the Sinpson method. From numerical calculation, when , T0=300K, Ta=350K and Tb=1 750K, the thermal stress distributions in the composite FGM plate were obtained. The results are as follows. With the increase of the FGM gradient layer thickness and when M=1, the temperature distributions in the composite plate are more reasonable. With the increase of the FGM gradient layer M, the thermal stresses on the ceramic surface tend toward reduction, and compared with the thermal stress of M=0.2, the thermal stress of M =5 reduces by 17.8%. When we take into account the effect of temperature-dependent material properties, compared with the results of constant material properties, the maximum compressive stress on the surface of metal reduces by 74.2%, and the maximum compressive stress on the surface of ceramics reduces by 45.3%. With the increase of FGM layer porosity P, the change of stress at the bonding interface of the three-layered plate increases, and the stress curves appear peak values. Compared with A=0, when A=3.99, the compressive thermal stress on the metal surface reduces by 42.0%, and the compressive thermal stress on the ceramic surface increases by 154.7%. Compared with the nongraded two-layered ceramic/metal composite plate, the thermal stress of the ZrO2/FGM/ Ti-6Al-4V composite plate is very gentle. Compared with , when , the maximum compressive stress on the surface of metal reduces by 49.98%, and the maximum compressive stress on the surface of ceramics increases by 182.3%. The results provide the foundations of theoretical calculation for the design and application of the composite plate.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

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