Embedded Elliptical Crack at a Corner

1978 ◽  
Vol 100 (1) ◽  
pp. 28-33
Author(s):  
A. S. Kobayashi ◽  
A. F. Emery ◽  
W. J. Love ◽  
A. Antipas
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Concentration ◽  
High Stress ◽  
Elliptical Crack ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Magnification Factors ◽  
Elliptical Cracks ◽  
Circular Cracks

A procedure for estimating the stress intensity factor of an embedded elliptical crack near the corner in a region of high stress concentration such as pressurized or thermally shocked nozzle-to-cylinder junction is discussed. The procedure is then used to analyze two hypothetical embedded circular cracks near the corner of a nozzle-to-cylinder junction where stress distributions in the uncracked junction are known. Also shown are two new stress intensity magnification factors for two embedded elliptical cracks, i.e., b/a = 0.2 and 0.982, close to a free corner, i.e., a/h = b/h = 0.9.

scholarly journals Thermo-mechanical stress analysis of dissimilar material joints using FEM

2020 ◽  
Vol 4 (2) ◽  
pp. 147-154
Author(s):  
Somnath Somadder
Keyword(s):  
Stress Concentration ◽  
Numerical Investigation ◽  
High Stress ◽  
Dissimilar Materials ◽  
Theory Of Elasticity ◽  
Dissimilar Material ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Thermal Expansion Coefficients ◽  
The Difference

Abstract: This article presents numerical investigation of isotropic dissimilar material joints. Dissimilar material joints are broadly used in in various structures, including offshore, nuclear, electronic packaging, IC chip and spacecraft various fields of science and technology. In bi-material joints two different material are bonded with common interface region. High stress concentration occur at the interface of the joint under thermo-mechanical loadings due to the difference in the elastic properties and the thermal expansion coefficients of dissimilar materials. The stresses acting along the interface of dissimilar material joints are very important to determine whether the structure is reliable or not for operation. The main purpose of this research is to provide finite element solutions to predict the stress distribution at the interface of the joint based on the theory of elasticity. Keywords: Numerical Investigation, Dissimilar material joints, Stress concentration, Stress distributions, Theory of elasticity.

A FE Model to Predict the Stress Concentration Factors in the Tensile Armor Wires of Flexible Pipes Inside End Fittings

2013 ◽  
Author(s):  
José Renato M. de Sousa ◽  
George C. Campello ◽  
Fabiano Bertoni ◽  
Gilberto B. Ellwanger
Keyword(s):  
Stress Concentration ◽  
High Stress ◽  
Axial Stiffness ◽  
Fe Model ◽  
Acceptance Test ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Flexible Pipes ◽  
The Wire ◽  
Stress Concentration Factors

In this work, a bidimensional finite element (FE) approach is proposed to estimate the stresses induced in the tensile armor wires inside end fittings (EF) of flexible pipes. This approach accounts for the residual stresses caused by the mounting procedure and the deformed configuration of the wire. The resin and its interaction with the wires are also addressed. A parametric study was performed aiming at investigating the influence of three parameters on the stress state along the wire, i. e., the contact conditions between the resin and the wire inside the EF, the stress levels induced during the factory acceptance test (FAT) or the offshore leak test (OLT) and the resin elastic properties. The study pointed that high stress concentration is induced in the transition between the flexible pipe’s body and the EF and the stress distribution along the wire may be significantly affected by these parameters. Moreover, the apparent axial stiffness of the wire is also modified by its anchoring conditions, which may lead to non-uniform stress distributions among the wires of the tensile armor layers.

Stress Intensity Incubation Periods for the Al-Hg Coupled Subjected to LME

2010 ◽  
Author(s):  
Scott G. Keller ◽  
Ali P. Gordon
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Intensity Factor ◽  
Liquid Metal ◽  
Failure Mechanism ◽  
Negative Impact ◽  
Structural Materials ◽  
Ductile Material ◽  
Brittle Behavior

When in the presence of liquid metal environments, structural materials can potentially lose the ability to deform and plastically flow. In the case of a ductile material, the result of this reduction in flow ability is a transition from ductile to brittle behavior, resulting in a brittle-like failure. This phenomenon is known as liquid metal embrittlement (LME) and is a subset of the more commonly known family of environmentally assisted cracking (EAC). Both EAC and LME have a significant negative impact on structural materials that are designed to behave elastically. Previous research in all facets of EAC, including stress corrosion cracking (SCC), corrosion fatigue (CF) and LME, has revealed that structural materials subjected to loading will generate and propagate cracks at stresses and stress intensities well below the critical values for that material. Additionally, crack tip velocities have been predicted and observed to be orders of magnitude greater than in ambient environments, with velocities in the range of tens to hundreds of centimeters per second. A variety of experimental routines have been used to characterize the interaction and develop microstructural failure mechanism in LME; however, uncertainty still surrounds the true failure mechanism. In a novel experimental approach, the dependence of the stress intensity factor (SIF) on crack propagation in the presence of a liquid metal was observed. Fracture mechanics specimens machined from Al7075-T651 in the S-L orientation were fatigue pre-cracked and incubated under load while submersed in liquid mercury. The result was the observation of rupture times over a range of stress intensity factors. It was noted that any stress concentration could provide the necessary criterion for crack initiation and propagation, regardless of the presence of a crack. Critical stresses and critical microstructural orientations dictated rupture paths more so than a pre-formed fatigue crack. Further experimentation, involving original and novel methods, has been conducted to determine the relationship between the stress intensity factor, stress concentration and microstructural orientation. Ultimately, the goal to confirm, extend or reject current microstructural failure mechanisms can be achieved through continued experimental routines.

Computation of Theoretical Stress Concentration Factor of V Shaped Notch Tip

2012 ◽  
Vol 152-154 ◽  
pp. 765-769
Author(s):  
Li Jun Zhang ◽  
Jie Qiong Xue ◽  
Yong Rui Zhao ◽  
Heng Fu Xiang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Groove Depth ◽  
Engineering Practice ◽  
Notch Tip ◽  
Theoretical Stress ◽  
Theoretical Stress Concentration Factor

To obtain the crack life and value of the external load applied on the bar in the course of the bar precision cropping, the mathematic expression of the theoretical stress concentration factor in the tip of the V shaped notch containing its geometric parameters is built theoretically by analyzing the stress field distribution of V shaped notch tip and the stress intensity factor. The influences of the flare angle Φ, the radius at the groove bottom, and the groove depth d on the theoretical stress concentration factor are analyzed in detail and the obtained rational value is d/D=0.1 , s/D=0.015, Φ=90 in engineering practice. The analytical results show that the data obtained by the mathematic expression of theoretical stress concentration factor in the tip of the V shaped notch presented in the paper are coincident with the results of the corresponding parameters obtained by stress concentration manual in some extension.

Fracture Assessments of High Pressure Vessel Components Having Longitudinal Holes

2017 ◽  
Author(s):  
Yu Xu ◽  
Kuao-John Young
Keyword(s):  
High Pressure ◽  
Stress Concentration ◽  
Fracture Mechanics ◽  
Pressure Vessel ◽  
High Stress ◽  
Pressure Vessels ◽  
Crack Face ◽  
High Pressure Vessel ◽  
High Stress Concentration ◽  
Critical Locations

Small size longitudinal holes are common in components of high pressure vessels. In fracture mechanics evaluation, longitudinal holes have not drawn as much attention as cross-bores. However, longitudinal holes become critical at certain locations for such assessments because of high stress concentration and short distance to vessel component wall. The high stress concentration can be attributed to three parts: global hoop stress that is magnified by the existence of the hole, local stresses due to pressure in the hole, and crack face pressure. In high pressure vessel design, axisymmetric models are used extensively in stress analyses, and their results are subsequently employed to identify critical locations for fracture mechanics evaluation. However, axisymmetric models ignore longitudinal holes and therefore cannot be used to identify the critical location inside the holes. This paper is intended to highlight the importance of including longitudinal holes in fracture mechanics evaluation, and to present a quick and effective way of evaluating high stress concentration at a longitudinal hole using the combined analytical solutions and axisymmetric stress analysis results, identifying critical locations and conducting fracture mechanics evaluation.

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