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.

Finite Element Analysis of Complex Corrosion Defects

2002 ◽  
Author(s):  
Duane S. Cronin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Burst Pressure ◽  
Uniaxial Tensile ◽  
Element Analysis ◽  
Internal Corrosion ◽  
Corrosion Defect ◽  
Elastic Plastic ◽  
Defect Assessment ◽  
Corrosion Defects

Aging gas and oil transmission pipeline infrastructure has led to the need for improved integrity assessment. Presently, external and internal corrosion defects are the leading cause of pipeline failure in Canada, and in many other countries around the world. The currently accepted defect assessment procedures have been shown to be conservative, with the degree of conservatism varying with the defect dimensions. To address this issue, a multi-level corrosion defect assessment procedure has been proposed. The assessment levels are organized in terms of increasing complexity; with three-dimensional elastic-plastic Finite Element Analysis (FEA) proposed as the highest level of assessment. This method requires the true stress-strain curve of the material, as determined from uniaxial tensile tests, and the corrosion defect geometry to assess the burst pressure of corrosion defects. The use of non-linear FEA to predict the failure pressure of real corrosion defects has been investigated using the results from 25 burst tests on pipe sections removed from service due to the presence of corrosion defects. It has been found that elastic-plastic FEA provides an accurate prediction of the burst pressure and failure location of complex-shaped corrosion defects. Although this approach requires detailed information regarding the corrosion geometry, it is appropriate for cases where an accurate burst pressure prediction is necessary.

scholarly journals Optimizing the thermal gradient and the pulling speed in a thermoplastic pultrusion process of PET/E glass fibers using finite element method

10.30544/367 ◽  
2018 ◽  
Vol 24 (2) ◽  
pp. 103-112 ◽  
Author(s):  
Nataša Z Tomić ◽  
Marija Vuksanović ◽  
Bojan Međo ◽  
Marko Rakin ◽  
Dejan Trifunović ◽  
...  
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Thermal Gradient ◽  
Ethylene Terephthalate ◽  
Glass Fibers ◽  
Element Analysis ◽  
Pultrusion Process ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Two Parameters

A thermoplastic pultrusion process was examined using commercial fiber roving of PET/E glass, to determine the optimum pulling speed and optimal zonal temperatures. Finite element analysis predicted heat transfer through the commingled fibers and air in the pultrusion die. The cross-section of obtained rods was examined, and image analysis was carried out to obtain information about the degree of fiber impregnation, number of voids and uniformity of fiber distribution. Optimizing the temperature field for the pultrusion of poly (ethylene terephthalate) is of significant importance. The pulling speed has the same importance. These two parameters are closely related as evidenced by the analysis of images.

scholarly journals Comparison of Fracture Methodologies for Flaw Stability Analysis of Storage Tanks

2004 ◽  
Author(s):  
P.-S. Lam ◽  
R. L. Sindelar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stability Analysis ◽  
Full Range ◽  
Storage Tanks ◽  
Element Analysis ◽  
Curvature Correction ◽  
Failure Assessment ◽  
Estimation Scheme ◽  
J Estimation

Fracture mechanics methodologies for flaw stability analysis of a storage tank were compared in terms of the maximum stable through-wall flaw sizes or “instability lengths.” The comparison was made at a full range of stress levels at a specific set of mechanical properties of A285 carbon steel and with a specific tank configuration. The two general methodologies, the J-integral-tearing modulus (J-T) and the failure assessment diagram (FAD), and several specific estimation schemes were evaluated. A finite element analysis of a flawed tank was also performed for validating the J estimation scheme with a curvature correction and for constructing the finite element-based FAD. The calculated instability crack lengths show that the J-T methodology based on a center-cracked panel solution with a curvature correction, and the material-specific FAD, most closely approximate the result calculated with finite element analysis for the stresses at the highest fill levels in the storage tanks (less than 124 MPa or 18 ksi). The results from the other FAD methods show instability lengths less than the J-T results over this range.

Effect of Defect on Elastic/Plastic and Creep Behavior of Bone: A Finite Element Study

2007 ◽  
Author(s):  
A. Ajdari ◽  
P. K. Canavan ◽  
H. Nayeb-Hashemi ◽  
G. Warner
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Trabecular Bone ◽  
Fatigue Loading ◽  
Dimensional Structure ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Local Bone ◽  
Osteoporotic Vertebral Fractures

Three-dimensional structure of trabecular bone can be modeled by 2D or 3D Voronoi structure. The effect of missing cell walls on the mechanical properties of 2D honeycombs is a first step towards understanding the effect of local bone resorption due to osteoporosis. In patients with osteoporosis, bone mass is lost first by thinning and then by resorption of the trabeculae [1]. Furthermore, creep response is important to analyze in cellular solids when the temperature is high relative to the melting temperature. For trabecular bone, as body temperature (38 °C) is close to the denaturation temperature of collagen (52 °C), trabecular bone creeps [1]. Over the half of the osteoporotic vertebral fractures that occur in the elderly, are the result of the creep and fatigue loading associated with the activities of daily living [2]. The objective of this work is to understand the effect of missing walls and filled cells on elastic-plastic behavior of both regular hexagonal and non-periodic Voronoi structures using finite element analysis. The results show that the missing walls have a significant effect on overall elastic properties of the cellular structure. For both regular hexagonal and Voronoi materials, the yield strength of the structure decreased by more than 60% by introducing 10% missing walls. In contrast, the results indicate that filled cells have much less effect on the mechanical properties of both regular hexagonal and Voronoi materials.

Elastic and elastic-plastic finite element analysis of hollow tubes with axisymmetric internal projections under combined axial and pressure loading

2001 ◽  
Vol 36 (4) ◽  
pp. 373-390 ◽  
Author(s):  
S. J Hardy ◽  
M. K Pipelzadeh ◽  
A. R Gowhari-Anaraki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Axial Loading ◽  
Material Model ◽  
Pressure Loading ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Applied Loading

This paper discusses the behaviour of hollow tubes with axisymmetric internal projections subjected to combined axial and internal pressure loading. Predictions from an extensive elastic and elastic-plastic finite element analysis are presented for a typical geometry and a range of loading combinations, using a simplified bilinear elastic-perfectly plastic material model. The axial loading case, previously analysed, is extended to cover the additional effect of internal pressure. All the predicted stress and strain data are found to depend on the applied loading conditions. The results are normalized with respect to material properties and can therefore be applied to geometrically similar components made from other materials, which can be represented by the same material models.

The Finite Element Analysis of Plate's Distance on Push-Extend Multi-under-Reamed Pile

2012 ◽  
Vol 468-471 ◽  
pp. 2517-2520 ◽  
Author(s):  
Xin Ying Xie ◽  
Xin Sheng Yin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bearing Capacity ◽  
Element Analysis ◽  
Elastic Plastic ◽  
The Finite Element Analysis ◽  
Plastic Theory

In this paper ,it analyses the push-extend multi-under-reamed pile in use of elastic-plastic theory by the software ANSYS.It takes four push-extend multi-under-reamed piles which are the same except plates' distance.It introduces the realative theory to make the anlysis much more accuracy.The results which is taken by ANSYS are researched to find out the regularity and can certain the reasonable plate's distance to anlyze the bearing capacity of push-extend multi-under-reamed pile at the same time.

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