C(t) Estimation of Cracked Pipe Under Radial Thermal Gradient or Axial Displacement Control Load

2016 ◽  
Author(s):  
Jin-Ho Je ◽  
Kuk-Hee Lee ◽  
Yun-Jae Kim ◽  
Young-Ryun Oh
Keyword(s):  
Thermal Gradient ◽  
Radial Direction ◽  
Tensile Load ◽  
Bending Stress ◽  
Uniform Stress ◽  
Displacement Control ◽  
Element Analysis ◽  
Axial Tensile ◽  
Control Load

The present study analyzes the elastic follow-up factor under various secondary loads in the piping with cracks through finite element analysis. The secondary loads being considered included axial tensile load caused by the displacement applied in form of uniform stress through thickness and the load due to the thermal gradient in the radial direction applied as bending stress. According to this study, under displacement control loads, elastic follow-up factor can increase greatly.

scholarly journals Numerical Analysis on Tensile Properties of Grout-filled Splice Sleeve Rebars under ISO 834 Standard Fire

2018 ◽  
Vol 38 ◽  
pp. 03036 ◽  
Author(s):  
Yong Jun Liu ◽  
Chao Li ◽  
When Jun Zhou
Keyword(s):  
Tensile Properties ◽  
Fire Resistance ◽  
Tensile Load ◽  
Load Ratio ◽  
Reinforcing Bars ◽  
Element Analysis ◽  
Standard Fire ◽  
Axial Tensile ◽  
Stress Changes ◽  
Steel Bars

This paper presents some numerical simulation results of tensile properties of reinforcing bars spliced by grout-filled coupling sleeves under fire conditions to identify the effect of load ratio on fire resistance time of spliced reinforcing bars, which provide a useful base for predicting structural behaviors of pre-cast reinforced concrete buildings in fires. A spliced rebar system investigated in this paper consists of two equal-diameter steel reinforcing bars with 25mm diameter and a straight coupling sleeve with 50mm outer and 45mm inner diameters. As a result, the thickness of grout between steel bars and sleeves are 20mm. Firstly, the temperature distributions in steel bars connected by grout- filled coupling sleeves exposed to ISO 834 standard fire were calculated utilizing finite element analysis software ANSYS. Secondly, the stress changes in heated steel bars connected by grout-filled coupling sleeves under different constant tensile loads were calculated step by step until the rebar system failed due to fire. Thus, the fire resistant time of rebar spliced by grout-filled coupling sleeves under different axial tensile loads can be determined, further, the relationship between fire resistance time and axial tensile loads ratio can could be obtained. Finally, the fire resistant times versus axial tensile load ratios curve of grout-filled splice sleeve rebars exposed to ISO 834 standard fire is presented.

Thermo-structural analysis of cryogenic tanks with common bulkhead configuration

2021 ◽  
pp. 095441002110247
Author(s):  
S Sumith ◽  
R Ramesh Kumar
Keyword(s):  
Structural Analysis ◽  
Temperature Gradient ◽  
Thermal Gradient ◽  
Load Transfer ◽  
Thermal Analyses ◽  
Positive Margin ◽  
Heat Transfer Analysis ◽  
Liquid Oxygen ◽  
Launch Vehicles ◽  
Element Analysis

In launch vehicles, cryogenic propulsion stages store liquid oxygen (LOX) at 76 K and liquid hydrogen (LH2) at 20 K, generally in two separate insulated tanks connected through tubular truss components. Consequently, load transfer from the LH2 tank to the LOX tank is very much localized, resulting in a nonoptimal design. This article presents an alternative single tankage design using a common bulkhead (CBH) to enhance the payload capability, which enables maintaining LH2 temperature within a specified temperature when exposed to a temperature gradient. A sandwich insulator using aramid honeycomb embedded with polyimide foam keeps the LH2 temperature within 20 ± 1 K is proposed, based on transient heat transfer analysis for 1000 s. The foam-filled honeycomb core is treated as equivalent foam in the analysis as the thermal conductivity of the core and the foam is quite close. The efficacy of the insulator is established by an experiment to measure the back wall temperature when liquid nitrogen is loaded on the top skin of the panel, and the insulator maintains a temperature gradient of 123 K for 1000 s. A good agreement is obtained between the transient finite element analysis results with experimental data. An externally insulated LOX tank configuration with an optimum length of the skirt–cylinder where the temperature reaches 80 K is arrived at based on slosh, buckling, and thermal analyses. No thermal gradient is found across the thickness of the skirt, while the thermal gradient is observed along the length of the skirt as anticipated. An integrated thermo-structural analysis of the cryo-system is carried out considering temperature-dependent material properties. A positive margin for the skirt is obtained. A payload gain of 366 kg is estimated based on the present study for the new design option with a CBH and skirt as compared to the traditional tubular truss arrangements.

SEM in situ study on the mechanical behaviour of SiCf/Ti composite subjected to axial tensile load

2011 ◽  
Vol 528 (13-14) ◽  
pp. 4507-4515 ◽  
Author(s):  
Kashif Naseem ◽  
Yanqing Yang ◽  
Xian Luo ◽  
Bin Huang ◽  
Guanghai Feng
Keyword(s):  
Mechanical Behaviour ◽  
Tensile Load ◽  
In Situ Study ◽  
Axial Tensile

Analysis of Premium Connection of Connecting and Sealing Ability Loaded by Axial Tensile Loads

2012 ◽  
Vol 268-270 ◽  
pp. 737-740
Author(s):  
Yang Yu ◽  
Yi Hua Dou ◽  
Fu Xiang Zhang ◽  
Xiang Tong Yang
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Tensile Load ◽  
Element Model ◽  
Sealing Ability ◽  
Axial Tensile ◽  
High Level ◽  
Maximum Contact ◽  
Contact Pressures ◽  
The Finite Element Model

It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

scholarly journals A Novel Method for Tooth Bending Stress Calculation of Gears With Asymmetric Teeth

2021 ◽  
Author(s):  
Oguz DOGAN ◽  
Celalettin YUCE ◽  
Fatih KARPAT
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Element Model ◽  
Bending Stress ◽  
Element Analysis ◽  
Stress Calculation ◽  
Bending Stresses ◽  
New Equation ◽  
Asymmetric Factor

Abstract Today, gear designs with asymmetric tooth profiles offer essential solutions in reducing tooth root stresses of gears. Although numerical, analytical, and experimental studies are carried out to calculate the bending stresses in gears with asymmetric tooth profiles a standard or a simplified equation or empirical statement has not been encountered in the literature. In this study, a novel bending stress calculation procedure for gears with asymmetric tooth profiles is developed using both the DIN3990 standard and the finite element method. The bending stresses of gears with symmetrical profile were determined by the developed finite element model and was verified by comparing the results with the DIN 3990 standard. Using the verified finite element model, by changing the drive side pressure angle between 20° and 30° and the number of teeth between 18 and 100, 66 different cases were examined and the bending stresses in gears with asymmetric profile were determined. As a result of the analysis, a new asymmetric factor was derived. By adding the obtained asymmetric factor to the DIN 3390 formula, a new equation has been derived to be used in tooth bending stresses of gears with asymmetric profile. Thanks to this equation, designers will be able to calculate tooth bending stresses with high precision in gears with asymmetric tooth profile without the need for finite element analysis.

scholarly journals Fabrication of Optimally Micro-Textured Copper Substrates by Plasma Printing for Plastic Mold Packaging

2020 ◽  
Vol 14 (2) ◽  
pp. 200-207 ◽  
Author(s):  
Tatsuhiko Aizawa ◽  
Yasuo Saito ◽  
Hideharu Hasegawa ◽  
Kenji Wasa ◽  
◽  
...  
Keyword(s):  
Stress Distribution ◽  
Copper Substrate ◽  
Three Dimensional ◽  
Picosecond Laser ◽  
Numerical Control ◽  
Uniform Stress ◽  
Element Analysis ◽  
Micro Grooving ◽  
Plastic Mold ◽  
Screen Printed

Micro-embossing using plasma printed micro-punch was proposed to form micro-groove textures into the copper substrate for plastic packaging of hollowed GaN HEMT-chips. In particular, the micro-groove network on the copper substrate was optimized to attain uniform stress distribution with maximum stress level being as low as possible. Three-dimensional finite element analysis was employed to investigate the optimum micro-grooving texture-topology and to attain the uniform stress distribution on the joined interface between the plastic mold and the textured copper substrate. Thereafter, plasma printing was utilized to fabricate the micro-punch for micro-embossing of the micro-grooving network into the copper substrate as a designed optimum micro-texture. This plasma printing mainly consisted of three steps. Two-dimensional micro-pattern was screen-printed onto the AISI316 die surface as a negative pattern of the optimum CAD data. The screen-printed die was plasma nitrided at 673 K for 14.4 ks at 70 Pa under the hydrogen-nitrogen mixture for selective nitrogen supersaturation onto the unprinted die surfaces. A micro-punch was developed by mechanically removing the printed parts of die material. Then, fine computer numerical control (CNC) stamping was used to yield the micro-embossed copper substrate specimens. Twelve micro-textured substrates were molded into packaged specimens by plastic molding. Finally, gross leak testing was employed to evaluate the integrity of the joined interface. The takt time required to yield the micro-grooved copper substrate by the present method was compared to the picosecond laser micro-grooving; the former showed high productivity based on this parameter.

Elastic-Plastic J-Estimation for Circumferentially Cracked Pipes Under Combined Mechanical and Thermal Loadings

2013 ◽  
Author(s):  
Chang-Young Oh ◽  
Yun-Jae Kim ◽  
R. A. Ainsworth
Keyword(s):  
Finite Element ◽  
Thermal Gradient ◽  
Order Effects ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Defect Assessment ◽  
Failure Assessment ◽  
Two Parameters ◽  
J Estimation

This paper addresses load order effects on elastic-plastic J estimation under combined mechanical and thermal loads for circumferentially cracked pipes. The load order effects, for various thermal gradient types and mechanical loading, are evaluated for a range of magnitudes of the loadings, crack sizes and material hardening. Variations of elastic-plastic J obtained by finite element analysis are compared with existing and proposed methods for use with the R6 defect assessment procedure. The load order effects are presented on the R6 failure assessment diagram (FAD) by calculating the two parameters Kr and Lr from the finite element results. It is shown that there are significant load order effects at large secondary stress cases but these are successfully treated by simplified methods proposed for use with R6.

scholarly journals Numerical Simulation on Thermodynamics Performance in the Fireproof Sealing by Finite Element Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Shuai Gao ◽  
Guoqing Zhu ◽  
Yunji Gao ◽  
Guoqiang Chai ◽  
Jinju Zhou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Field ◽  
Thermal Gradient ◽  
Thermal Flux ◽  
Ansys Software ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Thermodynamic Performance ◽  
Temperature Time

In this paper, the finite element analysis was firstly employed to investigate the thermal analysis on two fireproof sealing models with ANSYS software under HC standard temperature-time condition. The main thermal parameters were analyzed and obtained, including temperature field, thermal flux, and thermal gradient. After comparing the two fireproof sealing models, the major conclusions are summarized as follows: In terms of temperature field, the temperature on the left side of the first model ranges from 60 to 524°C in. In contrast, the highest temperature on the left side of the second model eventually reaches below 151°C. Moreover, the vectors of thermal gradient in the first model are compared with the second model, and the temperature gradient disturbance is more obvious in the second fireproof sealing model, which is better to slow down temperature spreading. The accelerated speed of E1 and G1 is 0.0096°C/s and 0.0619°C/s partly, which are far more than C2 and F2 with values of 0.0028°C/s and 0.0078°C/s, respectively. In a word, the performance of the first fireproof sealing model is inferior to the second fireproof sealing model. The conclusions of the study are meaningful to improve the thermodynamic performance of the fireproof sealing in the converter station.

scholarly journals Finite-element-analysis of the mechanical behavior of high-frequency litz wire in flat coil winding

2020 ◽  
Vol 14 (5-6) ◽  
pp. 555-567
Author(s):  
Michael Weigelt ◽  
Cornelius Thoma ◽  
Erdong Zheng ◽  
Joerg Franke
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Behavior ◽  
High Frequency ◽  
Common Property ◽  
Computational Effort ◽  
Bending Stress ◽  
Element Analysis ◽  
Technical Requirements ◽  
Coil Winding

AbstractNumerous applications of daily life use flat coils, e.g. in the automotive area, in solar technology and in modern kitchens. One common property that all these applications share, is a flat coil made of high-frequency (HF) litz wires. The coil layout and the properties of the HF litz wire influence the winding process and the efficiency of the application. As a result, the HF litz wire must meet the complex technical requirements of the winding process and of the preferred mechanical, electromagnetic and thermal properties of the HF litz wire itself. Therefore, a reasonable configuration and optimization of HF litz wire has been developed with the help of a finite-element-analysis (FEA). In this work, it is first shown that the mechanical behavior of HF litz wire under tensile and bending stress can be simulated. Since the computational effort for modelling an HF litz wire at the single conductor level is hardly manageable, a suitable modelling strategy is developed and applied using geometric analogous models (GAM). By using such a model, HF litz wires can be designed for the specific application and their behavior in a winding process can be predicted.

scholarly journals Strain Capacity of Girth Welded Joints in HSAW Pipes

2017 ◽  
Author(s):  
Koen Van Minnebruggen ◽  
Stijn Hertelé ◽  
Wim De Waele
Keyword(s):  
Welded Joints ◽  
Structural Integrity ◽  
Tensile Load ◽  
Tensile Loading ◽  
Experimental Result ◽  
Large Strains ◽  
Automatic Welding ◽  
Strain Capacity ◽  
Axial Tensile ◽  
Welding Processes

The general aim of a recently finalized European project, i.e. EU RFCS SBD-Spipe, is to generate specific know-how concerning the development and possible use of spirally welded pipes for demanding applications. The demanding applications relate especially to structural integrity issues, both onshore and offshore, requiring good performance under application of large strains resulting in buckling, collapse and/or tensile loading. The outcome of this project can also be used as technical basis for improving standards and guidelines, that address design and safety of spirally welded pipelines. The contribution of Ghent University to this project focusses on the aspects of tearing resistance, defect tolerance and strain capacity of girth welded joints subjected to remote axial tensile load. A numerical and experimental approach is used for the assessment of flaw tolerability and strain development upon tensile loading. Spiral pipes of steel grade API-5L X70 with 36” and 48” diameters have been girth welded using both a manual and semi-automatic welding processes. Curved wide plate specimens have been extracted from the pipes and artificial weld defects have been introduced. The specimens have been loaded in tension up to failure at a temperature of −10°C. This paper reports on the experimental result of a series of curved wide plate tests.

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