On Determining Reference Stresses for High Temperature Thin/Thick Tube Bends

2005 ◽  
Author(s):  
Abheek Basu ◽  
Khosrow Zarrabi ◽  
Lawrence Ng
Keyword(s):  
High Temperature ◽  
Internal Pressure ◽  
Explicit Expression ◽  
Finite Volume ◽  
Limit Analysis ◽  
Volume Analysis ◽  
Reference Stress ◽  
First Time

It is well known that tube/pipe bends have some degree of ovality caused during their manufacture. For the first time, based on limit analysis, the authors previously presented an explicit expression for calculation of the reference stress of tube/pipe bends with varying degrees of ovality that are subjected to uniform internal pressure. The present paper assesses this expression using an elastic-creep finite volume analysis. This is due to availability of an in-house finite volume code. It is shown that the references stresses predicted by proposed expression correlate well with those computed using elastic-creep analyses for tube/pipe bends with various degrees of ovality.

Reference Stress Values for Toroidal Vessels Subjected to Uniform Internal Pressure

2004 ◽  
Author(s):  
Khosrow Zarrabi ◽  
Abheek Basu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Explicit Expression ◽  
The Finite Element Method ◽  
Creep Life ◽  
Reference Stress ◽  
Uniaxial Creep ◽  
Rupture Data ◽  
Internal Pressures

Using the finite element method, the paper presents an explicit expression for the reference stress of tube/pipe bends with various degrees of ovality that are subjected to uniform internal pressures. No such task has been accomplished before. The presented reference stress may be used in conjunction with the uniaxial creep rupture data to obtain the creep life of the bend.

Shakedown and Limit Analysis of Kinematic Hardening Piping Elbows Under Internal Pressure and Bending Moments

2021 ◽  
Author(s):  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Yield Strength ◽  
Internal Pressure ◽  
Limit Analysis ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Bending Moments ◽  
Plastic Limit ◽  
Plastic Limit Load ◽  
Interaction Curves ◽  
Shakedown Limit

Abstract In this paper, the Stress Compensation Method (SCM) adopting an elastic-perfectly-plastic (EPP) material is further extended to account for limited kinematic hardening (KH) material model based on the extended Melan's static shakedown theorem using a two-surface model defined by two hardening parameters, namely the initial yield strength and the ultimate yield strength. Numerical analysis of a cylindrical pipe is performed to validate the outcomes of the extended SCM. The results agree well with ones from literature. Then the extended SCM is applied to the shakedown and limit analysis of KH piping elbows subjected to internal pressure and cyclic bending moments. Various loading combinations are investigated to generate the shakedown limit and the plastic limit load interaction curves. The effects of material hardening, elbow angle and loading conditions on the shakedown limit and the plastic limit load interaction curves are presented and analysed. The present method is incorporated in the commercial finite element simulation software and can be considered as a general computational tool for shakedown analysis of KH engineering structures. The obtained results provide a useful information for the structural design and integrity assessment of practical piping elbows.

Xps Analysis of the Sapphire Surface as a Function of High Temperature Vacuum Annealing

1989 ◽  
Vol 159 ◽  
Author(s):  
E.D. Richmond
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Xps Analysis ◽  
Chemical Changes ◽  
Cleaning Procedure ◽  
Sapphire Surface ◽  
X Ray ◽  
First Time

ABSTRACTFor the first time the (1102) surface of sapphire has been investigated by X-ray photoelectron spectroscopy to ascertain chemical changes resulting from annealing in vacuum at 1300° C and 1450° C. As received substrates had a substantial surface C contaminant. For substrates that were chemically cleaned before inserting them into the MBE system no trace of carbon is detected. A residual flourine contaminant results from the cleaning procedure and is desorbed by the vacuum annealing. Spectra of annealed substrates are compared to the unannealed chemically cleaned substrates. The annealed substrates exhibit 0.4 to 0.5 eV shift to higher binding energy of the Al peak and a 0.3 eV shift to higher binding energy of the O peak. In addition, a 2% depletion of oxygen from the surface occurs.

Study on Superalloy Tube Extrusion Process Using Finite Volume Method

2012 ◽  
Vol 572 ◽  
pp. 267-272
Author(s):  
Yi Lun Mao ◽  
Qing Dong Zhang ◽  
Chao Yang Sun ◽  
Xiao Feng Zhang
Keyword(s):  
Mathematical Model ◽  
High Temperature ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Extrusion Process ◽  
Equivalent Strain ◽  
High Temperature Alloy ◽  
Squeeze Pressure ◽  
Tube Extrusion ◽  
Volume Method

In this paper, complexity of the process of high temperature alloy tubing extrusion is studied using the Finite Volume Method (FVM). We establish mathematical model of high temperature alloy tube extrusion process by using the Finite Volume Method. We develop the simulation program by the control equation of the Finite Volume Method and numerical simulation of the key technologies of the axisymmetric problem in cylindrical coordinates. Inconel690 high temperature alloy tubing extrusion process, for example, we got the squeeze pressure in the steady-state extrusion, Velocity field and the corresponding equivalent strain rate field. By comparing the results obtained by the finite volume method and simulation results from Finite Element Method (FEM) software on DEFORM-2D, we find our mathematical model on high temperature alloy tubing extrusion process is reasonable and correct.

scholarly journals The Influence of pH and Temperature on Water as a Pressurized Fluid in the Extraction of Bioactive Myconutrients from Chaga Mushroom (Inonotus obliquus)

2021 ◽  
Author(s):  
Ibrahim M. Abu-Reidah ◽  
Amber Critch ◽  
Charles Manful ◽  
Amanda Rajakaruna ◽  
Natalia Prieto Vidal ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Temperature ◽  
Phenolic Compounds ◽  
Total Phenolic ◽  
Acidic Ph ◽  
Inonotus Obliquus ◽  
Food Grade ◽  
Green Food ◽  
Fat Soluble Vitamins ◽  
First Time

Mushrooms have long rich history in folk medicine, traditional and functional foods due to high content of dietary myco-nutrients. Currently, there is increased interest in finding appropriate food-grade green ex-traction systems capable of extracting these bioactive compounds from dietary mushrooms for applica-tions in various food, pharmacological or nutraceutical formulations. Herein, we evaluated a modified Swiss water process (SWP) method using alkaline and acidic pH at low and high temperature under pressurized conditions as a suitable green food grade solvent to obtained extracts enriched with my-co-nutrients (dietary phenolics, total antioxidants (TAA), vitamins, and minerals) from Chaga. Ultra-high performance liquid chromatography coupled to high resolution accurate mass tandem mass spectrometry (UHPLC-HRAMS-MS/MS) was used to assess the phenolic compounds and vitamin levels in the extracts, while inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the mineral con-tents. Over twenty phenolic compounds were quantitatively evaluated in the extracts and the highest total phenolic content and antioxidant activity was observed at pH11.5 at 100°C. The most abundant phenolic compounds present in Chaga extracts included phenolic acids such as protocatechuic acid 4-glucoside (0.7-1.08µg/mL), syringic acid (0.62-1.18µg/mL), and myricetin (0.68-1.3µg/mL). Vitamins are being reported for the first time in Chaga. pH 2.5 at 100°C treatment shows superior effects in extracting the B vitamins whereas pH 2.5 at 60 and 100°C treatments were outstanding for extraction of total fat-soluble vitamins. Vitamin E content was the highest for the fat-soluble vitamins in the Chaga extract under acidic pH (2.5) and high temp. (100°C) and ranges between 50 to 175 µg/100g Chaga. Antioxidant minerals ranged from 85.94 µg/g (pH7 at 100°C) to 113.86 µg/g DW (pH2.5 at 100°C). High temperature 100°C and a pH of 2.5 or 9.5. The treatment of pH11.5 at 100°C was the most useful for recovering phenolics and antioxidants from Chaga including several phenolic compounds reported for the first time in Chaga. SWP is being proposed herein for the first time as a novel, green food-grade solvent system for the extraction of myco-nutrients from Chaga and have potential applications as a suitable approach to extract nutrients from other matrices. Chaga extracts enriched with bioactive myconutrients and antioxidants may be suitable for further use or applications in the food and nutraceutical industries.

A Finite Volume Analysis of the Thermohydrodynamic Performance of Finite Journal Bearings

1990 ◽  
Vol 112 (3) ◽  
pp. 557-565 ◽  
Author(s):  
T. Han ◽  
R. S. Paranjpe
Keyword(s):  
Finite Volume ◽  
Numerical Scheme ◽  
Reverse Flow ◽  
Journal Bearings ◽  
Simultaneous Solution ◽  
Volume Analysis ◽  
Recirculating Flow ◽  
Supply Pressure ◽  
Good Sample ◽  
Energy Equations

A rigorous thermohydrodynamic (THD) analysis of finite journal bearings has been developed. THD analysis not only allows a more accurate prediction of the bearing performance characteristics, but it also provides the temperature distribution in the bearing. It involves the simultaneous solution of the Reynolds and energy equations and can handle a wide variety of flow situations, including reverse flow, recirculating flow, and cavitation. The overall numerical scheme is based on a fully conservative finite-volume formulation. The calculated results are compared with the published literature. The qualitative agreement is good. Sample calculations for a typical automotive bearing show that the oil supply pressure and supply configuration significantly affect the bearing performance.

Niobium-bearing arsenides and germanides from elemental mixtures not involving niobium: a new twist to an old problem in solid-state synthesis

2018 ◽  
Vol 74 (5) ◽  
pp. 623-627 ◽  
Author(s):  
Sviatoslav Baranets ◽  
Hua He ◽  
Svilen Bobev
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Diffraction Data ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Reactions ◽  
First Time ◽  
Synthetic Work

Three isostructural transition-metal arsenides and germanides, namely niobium nickel arsenide, Nb0.92(1)NiAs, niobium cobalt arsenide, NbCoAs, and niobium nickel germanide, NbNiGe, were obtained as inadvertent side products of high-temperature reactions in sealed niobium containers. In addition to reporting for the very first time the structures of the title compounds, refined from single-crystal X-ray diffraction data, this article also serves as a reminder that niobium containers may not be suitable for the synthesis of ternary arsenides and germanides by traditional high-temperature reactions. Synthetic work involving alkali or alkaline-earth metals, transition or early post-transition metals, and elements from groups 14 or 15 under such conditions may yield Nb-containing products, which at times could be the major products of such reactions.

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