Study on the Effect of Axial Flaw Length on Limit Bending Load of Wall Thinned Straight Pipes by Large Strain Finite Element Analyses

2012 ◽  
Author(s):  
Yoshiaki Ito ◽  
Toshiyuki Meshii
Keyword(s):  
Finite Element ◽  
Fracture Mode ◽  
Large Strain ◽  
Local Stress ◽  
Limit Load ◽  
Crack Model ◽  
Element Analysis ◽  
Bending Load ◽  
Load Analysis ◽  
Planar Flaw

In this paper, we examined the effect of axial flaw length δz (Fig. 1) on limit bending load Mc of wall-thinned straight pipes by large strain finite element analysis (FEA). In the past, Han et al. [1] studied the effect of axial flaw length δz on limit bending load Mc of wall-thinned straight pipes by limit-load analyses. Han et al.’s [1] results indicated the trend which the Mc monotonically decreased with the increase in δz. If this finding is accepted, the Mc for a crack is larger than that for a non-planar flaw (wall thinning), and as a result, using the crack model for a non-planar flaw would be non-conservative. In contrast, Tsuji and Meshii [2] demonstrated by their tests that the Mc showed the maximum for a small δz. They estimated that this inconsistency was mainly due to the fact that Han et al. [1] and other researchers always assumed the fracture mode as the collapse, but the cracking was observed in Tsuji’s [2] experiment for small δz. Therefore in this work, we examined the effect of axial flaw length δz on limit bending load Mc of wall-thinned straight pipes by large strain FEA and applying Domain Collapse Criterion (DCC) [3] (which can predict fracture mode and the Mc accurately) to FEA results. In concrete, we attempted to reproduce Tsuji and Meshii’s experimental results [2] by FEA that the Mc showed the maximum for a small δz. In addition, we tried to understand the reason why limit-load analysis failed to predict this tendency. The results showed that large strain FEA with DCC [3] reproduced the Mc-δz relationship observed in the experiments. The inconsistency of Mc-δz relationship between Tsuji and Meshii’s experiment [2] and Han et al.’s limit-load analysis [1] and others analysis was estimated on due to the limit-load analysis failed to predict the failure for the flaw with a small δz, in which the failure mode is governed by the local stress (cracking) and not by the plastic deformation in a large volume (collapse).

Use of Limit Load Analysis for Design of Pressure Vessel Cover

2012 ◽  
Author(s):  
Rahul Jain
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Limit Load ◽  
Plastic Limit ◽  
Element Analysis ◽  
Linear Elastic ◽  
Reference Volume ◽  
Plastic Limit Load ◽  
Load Analysis

This paper explores the use of limit load analysis methods for the design of a pressure vessel manway cover as per the ASME boiler and pressure vessel code guidelines. The results of elastic and limit load finite element analysis are discussed for the design. The concept of reference volume consideration along with linear elastic finite element analysis to determine the lower bound limit load has been explored and the results are compared with the non-linear elastic-plastic limit load analysis.

The Simulation and Assessment of Compressed Natural Gas Storage Well With Defects

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Wei Tan ◽  
JinJun Zhang ◽  
WeiFei Niu ◽  
ZeJun Wang ◽  
ShiLai Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Natural Gas ◽  
Iterative Methods ◽  
Fem Analysis ◽  
Limit Load ◽  
Liquefied Petroleum Gas ◽  
Element Analysis ◽  
Compressed Natural Gas ◽  
Load Analysis ◽  
Influence Radius

Compressed natural gas (CNG) is a fossil fuel substitute for gasoline (petrol), diesel, or propane/LPG (liquefied petroleum gas). Nowadays, there are three ways used to store CNG: gas bottles group, jumbo tubes trailer, and CNG storage well. The technology of storage well came into use in the early 1990s in China and nowadays, there are more than 5000 CNG storage wells in use. In this paper, the CNG storage well is introduced with the structure, advantages, and the technology of construction. Compared with other CNG containers, storage well has the following advantages: safer and more reliable, accident-preventive, space-saving, and longer life expectancy. The feasibility of IRIS (internal rotary system) used for storage well NDT (Nondestructive testing) is also studied. And the CNG well with defects are assessed as well. To investigate the validity of IRIS in detecting the storage well, an interval casing with man-made defects is tested. FEM (finite element method), combined with the method in JB4732 (Chinese industry standard) is used to analyze the storage well with inner corrosion pits, and evaluate the fatigue life. The linear elastic FEA (finite element analysis) of storage with single, two, and three defects is performed. The limit load analysis is also discussed with two different iterative methods. The result shows that IRIS can be used in detecting internal and external defects and recording the information. The simulation indicates that the pit along the axis direction is more dangerous than the one on any other direction and the influence radius of pit is the length of defect. The two different iterative methods used in limit load analysis finally lead to a consensus. The IRIS can be adopted in storage well. It can detect the defects on the internal and external surface of casing and record the detailed information. A database should be built to record defect information for each storage well. On the basis of IRIS detection and FEM analysis, determines whether a well can survive or not until next detection carried on by the method proposed in this paper.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

2013 ◽  
Vol 41 (1) ◽  
pp. 60-79 ◽  
Author(s):  
Wei Yintao ◽  
Luo Yiwen ◽  
Miao Yiming ◽  
Chai Delong ◽  
Feng Xijin
Keyword(s):  
Finite Element ◽  
High Efficiency ◽  
Force Measurement ◽  
Three Dimensional ◽  
Local Stress ◽  
Tension Force ◽  
Center Line ◽  
Element Analysis ◽  
Design Variables ◽  
Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

The Effects of Warm Pre-Stressing of a Pre-Cracked Pressurised Thermal Shock Disk Specimen Under a LUCF Loading Cycle

2011 ◽  
Author(s):  
H. Teng ◽  
D. W. Beardsmore ◽  
J. K. Sharples ◽  
P. J. Budden
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Thermal Shock ◽  
Local Stress ◽  
Superposition Method ◽  
Element Analysis ◽  
Loading Cycle ◽  
Finite Element Software ◽  
Disk Specimen ◽  
Apparent Fracture Toughness

A finite element analysis has been performed to investigate the effects of warm prestressing of a pre-cracked PTS-D (Pressurized Thermal Shock Disk) specimen, for comparison with the experimental work conducted by the Belgium SCK-CEN organisation under the European NESC VII project. The specimen was loaded to a maximum loading at −50 °C, unloaded at the same temperature, cooled down to −150 °C, and then re-loaded to fracture at −150 °C. This is a loading cycle known as a LUCF cycle. The temperature-dependant tensile stress-strain data was used in the model and the finite element software ABAQUS was used in the analysis. The finite element results were used to derive the apparent fracture toughness by three different methods: (1) Chell’s displacement superposition method; (2) the local stress matching method; and (3) Wallin’s empirical formula. The apparent fracture toughness values were derived at the deepest point of the semi-elliptical crack for a 5% un-prestressed fracture toughness of 43.96 MPam1/2 at −150 °C. The detailed results were presented in the paper.

Finite Element Analysis of Stress Singularities in Attached Flip Chip Packages

2000 ◽  
Vol 122 (4) ◽  
pp. 301-305 ◽  
Author(s):  
A. Q. Xu ◽  
H. F. Nied
Keyword(s):  
Contact Angle ◽  
Finite Element ◽  
Glass Fiber ◽  
Flip Chip ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Local Stress ◽  
Stress Singularities ◽  
Element Analysis ◽  
Three Dimensional Finite Element

Cracking and delamination at the interfaces of different materials in plastic IC packages is a well-known failure mechanism. The investigation of local stress behavior, including characterization of stress singularities, is an important problem in predicting and preventing crack initiation and propagation. In this study, a three-dimensional finite element procedure is used to compute the strength of stress singularities at various three-dimensional corners in a typical Flip-Chip assembled Chip-on-Board (FCOB) package. It is found that the stress singularities at the three-dimensional corners are always more severe than those at the corresponding two-dimensional edges, which suggests that they are more likely to be the potential delamination sites. Furthermore, it is demonstrated that the stress singularity at the upper silicon die/epoxy fillet edge can be completely eliminated by an appropriate choice in geometry. A weak stress singularity at the FR4 board/epoxy edge is shown to exist, with a stronger singularity located at the internal die/epoxy corner. The influence of the epoxy contact angle and the FR4 glass fiber orientation on stress state is also investigated. A general result is that the strength of the stress singularity increases with increased epoxy contact angle. In addition, it is shown that the stress singularity effect can be minimized by choosing an appropriate orientation between the glass fiber in the FR4 board and the silicon die. Based on these results, several guidelines for minimizing edge stresses in IC packages are presented. [S1043-7398(00)00904-X]

scholarly journals Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and In-Plane Bending for Ni-Fe-Cr B407 Material

2017 ◽  
Vol 62 (3) ◽  
pp. 1881-1887
Author(s):  
P. Ramaswami ◽  
P. Senthil Velmurugan ◽  
R. Rajasekar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Limit Load ◽  
Outer Radius ◽  
Factor H ◽  
Geometrical Shape ◽  
Element Analysis ◽  
Pipe Bend ◽  
Plane Bending

Abstract The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

J-Integral Analysis of Surface Cracks in Round Bars under Bending Moments

2011 ◽  
Vol 52-54 ◽  
pp. 43-48 ◽  
Author(s):  
Al Emran Ismail ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
Ruslizam Daud
Keyword(s):  
Finite Element ◽  
Crack Depth ◽  
Crack Tip ◽  
Bending Moment ◽  
Limit Load ◽  
Fe Model ◽  
Surface Cracks ◽  
Element Analysis ◽  
Reference Stress ◽  
Proposed Model

This paper presents a non-linear numerical investigation of surface cracks in round bars under bending moment by using ANSYS finite element analysis (FEA). Due to the symmetrical analysis, only quarter finite element (FE) model was constructed and special attention was given at the crack tip of the cracks. The surface cracks were characterized by the dimensionless crack aspect ratio, a/b = 0.6, 0.8, 1.0 and 1.2, while the dimensionless relative crack depth, a/D = 0.1, 0.2 and 0.3. The square-root singularity of stresses and strains was modeled by shifting the mid-point nodes to the quarter-point locations close to the crack tip. The proposed model was validated with the existing model before any further analysis. The elastic-plastic analysis under remotely applied bending moment was assumed to follow the Ramberg-Osgood relation with n = 5 and 10. J values were determined for all positions along the crack front and then, the limit load was predicted using the J values obtained from FEA through the reference stress method.

Zimmer Frame Use and Back Strain Analysis Using a Finite Element Model

2020 ◽  
Author(s):  
Sydney Harwood ◽  
Parisa Saboori
Keyword(s):  
Finite Element ◽  
Chronic Back Pain ◽  
Large Strain ◽  
Strain Analysis ◽  
Element Model ◽  
Erector Spinae ◽  
Aging Effects ◽  
Element Analysis ◽  
Frame Design ◽  
Lower Back

Abstract The current walking frame used by the elderly has several design issues that can cause long term health problems. One of these problems is the development of chronic pain in the lower back. The design of the current walking frame promotes a slumping posture that causes a curvature in the spine. This curvature results in a large strain in the lower back muscles, specifically the erector spinae. The goal of this research was to design a new walking frame that would be more structurally sound and more practical to use than the present walking frame design. In this study, two literature searches were performed. The first was to explore how aging effects the ability to walk. The second involved studying all of the existing walking devices and analyzing their design strengths and weaknesses. As a result of these studies, three new preliminary walking frame designs were considered that promoted better posture when used, and provided more support than does the present walking frame design. These new designs were considered and tested using a finite element analysis (FEA). From this FEA, it was determined that the new walking frame design resulted in less stress in the lower back than does the present walking frame design. It was therefore concluded that the new model has the potential to decease chronic back pain.

The Evaluation of Failure Pressure for Corrosion Defects Within Girth or Seam Weld in Transmission Pipelines

2004 ◽  
Author(s):  
Young-pyo Kim ◽  
Woo-sik Kim ◽  
Young-kwang Lee ◽  
Kyu-hwan Oh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Limit Load ◽  
The Body ◽  
Element Analysis ◽  
Burst Test ◽  
Corrosion Defect ◽  
Seam Weld ◽  
Failure Assessment ◽  
Corrosion Defects

The failure assessment for corroded pipeline has been considered with the burst test and the finite element analysis. The burst tests were conducted on 762mm diameter, 17.5mm wall thickness and API 5L X65 pipe that contained specially manufactured rectangular corrosion defect. The failure pressures for corroded pipeline have been measured by burst testing and classified with respect to corrosion sizes and corroded regions — the body, the girth weld and the seam weld of pipe. Finite element analysis was carried out to derive failure criteria of corrosion defect within the body, the girth weld and the seam weld of the pipe. A series of finite element analyses were performed to obtain a limit load solution for corrosion defects on the basis of burst test. As a result, the criteria for failure assessment of corrosion defect within the body, the girth weld and the seam weld of API 5L X65 gas pipeline were proposed.

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