A Simplified Method for Calculating Crack Opening Area

2002 ◽  
Author(s):  
E. Smith
Keyword(s):  
Plastic Deformation ◽  
Stress Distribution ◽  
Crack Opening ◽  
Two Dimensional ◽  
Simple Method ◽  
Tensile Stresses ◽  
Normal Operating ◽  
General Stress ◽  
Simplified Method ◽  
Leak Before Break

In the context of the formulation of a leak-before-break case for a component in a pressurized system, this paper is concerned with the quantification of the crack opening area associated with a two-dimensional crack that is subjected to tensile stresses. We present a simple method, based on the strip yield representation of plastic deformation, for calculating the area. The method is validated against the known result for the ease of an isolated crack in a uniformly stressed infinite solid. It is then used for a general stress distribution, as might arise from a combination of pressure induced and weld residual tensile stresses, with the considerations being focussed on the case where plastic deformation is limited, as is usually appropriate for normal operating situations; application of the method is then especially simple.

Calculating Crack Opening Area for the Limited Plasticity Situation

2003 ◽  
Author(s):  
E. Smith
Keyword(s):  
Plastic Deformation ◽  
Stress Distribution ◽  
Crack Opening ◽  
Two Dimensional ◽  
Flow Properties ◽  
General Applicability ◽  
Tensile Stresses ◽  
Normal Operating ◽  
Elastic Crack ◽  
Leak Before Break

When formulating a leak-before-break case for a component in a pressurized system, it is essential to quantify the opening area associated with a crack that is subjected to the tensile stresses that are appropriate to normal operating situations. In a paper presented at the 2002 PVP Conference, the author presented a simple and exact method, based on the strip yield representation of plastic deformation, for calculating the area. The method was validated against the known result for the case of an isolated two-dimensional crack in a uniformly stressed infinite solid, but the method has general applicability. Special consideration was given to the case where plastic deformation is limited, as is usually appropriate for normal operating situations, and the method then simplifies considerably. This paper shows that the method, as it is applied to the limited plastic deformation situation, gives results which are the same as those obtained by use of the equivalent crack procedure, where an actual crack is replaced by an effective elastic crack, which is longer than the actual crack by an amount which is related to the flow properties of the material and the applied loadings. To illustrate the usefulness of the author’s method, it is applied to a specific stress distribution as might arise from a combination of pressure induced and weld residual tensile stresses.

Crack Opening Area for an Isolated Crack Subjected to a Symmetric Mode I Stress Distribution

2004 ◽  
Author(s):  
E. Smith
Keyword(s):  
Stress Distribution ◽  
Crack Opening ◽  
Operating Conditions ◽  
Mode I ◽  
Stress Distributions ◽  
Simple Derivation ◽  
Opening Displacement ◽  
System A ◽  
Simplified Procedure ◽  
Leak Before Break

In developing a leak-before-break case for a component in a pressurized system, a key element is an estimation of the size of through-thickness crack that will give a measurable leakage under normal operating conditions, and this requires a knowledge of the crack opening area. In this context, the paper presents a simple derivation of an expression for the crack opening area associated with an isolated crack that is subjected to a general Mode I symmetric tensile stress distribution which could arise from a combination of applied and residual stresses. The paper also presents a simple derivation of an expression for the crack opening displacement at the crack centre which, coupled with the assumption that the crack opening profile conforms to an elliptical shape, has been used as the basis for a simplified procedure for estimating the crack opening area. The resulting expressions are validated by comparing them with known results for specific stress distributions. They are also used to give new results for a cosine stress distribution.

A method for the measurement of residual stresses using a fracture mechanics approach

1989 ◽  
Vol 24 (1) ◽  
pp. 23-30 ◽  
Author(s):  
K J Kang ◽  
J H Song ◽  
Y Y Earmme
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Fracture Mechanics ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
The State ◽  
Two Dimensional ◽  
Finite Element Analyses ◽  
Simple Method

A simple method for measuring residual stresses in a plate is described. In this method residual stresses are evaluated using a fracture mechanics approach, that is, the strains or displacements measured at a point on the edge of a plate as a crack is introduced and extended from the edge are used to deduce the state of stresses that existed in the uncracked plate. Through finite element analyses and experiments this method is shown to be valid and effective for measuring the two-dimensional residual stress distribution of a welded plate.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

scholarly journals Two-Dimensional Visualization of the Three-Dimensional Planned Sacroiliac Screw Corridor with the Slice Fusion Method

2021 ◽  
Vol 10 (2) ◽  
pp. 184
Author(s):  
Maximilian Kerschbaum ◽  
Siegmund Lang ◽  
Florian Baumann ◽  
Volker Alt ◽  
Michael Worlicek
Keyword(s):  
Pelvic Ring ◽  
Three Dimensional ◽  
Fusion Method ◽  
Two Dimensional ◽  
Posterior Pelvic Ring ◽  
Simple Method ◽  
Sacroiliac Screw ◽  
Screw Insertion ◽  
Multiplanar Reconstructions ◽  
Screw Position

Insertion of sacro-iliac (SI) screws for stabilization of the posterior pelvic ring without intraoperative navigation or three-dimensional imaging can be challenging. The aim of this study was to develop a simple method to visualize the ideal SI screw corridor, on lateral two-dimensional images, corresponding to the lateral fluoroscopic view, used intraoperatively while screw insertion, to prevent neurovascular injury. We used multiplanar reconstructions of pre- and postoperative computed tomography scans (CT) to determine the position of the SI corridor. Then, we processed the dataset into a lateral two-dimensional slice fusion image (SFI) matching head and tip of the screw. Comparison of the preoperative SFI planning and the screw position in the postoperative SFI showed reproducible results. In conclusion, the slice fusion method is a simple technique for translation of three-dimensional planned SI screw positioning into a two-dimensional strict lateral fluoroscopic-like view.

scholarly journals Specific and general stress proteins in Bacillus subtilis - a two-dimensional protein electrophoresis study

Microbiology ◽  
1997 ◽  
Vol 143 (3) ◽  
pp. 999-1017 ◽  
Author(s):  
J. Bernhardt ◽  
U. Volker ◽  
A. Volker ◽  
H. Antelmann ◽  
R. Schmid ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Stress Proteins ◽  
Protein Electrophoresis ◽  
Two Dimensional ◽  
General Stress

Numerical Solution of Elastoplastic Torsion of a Shaft of Rotational Symmetry

1949 ◽  
Vol 16 (2) ◽  
pp. 139-148
Author(s):  
R. P. Eddy ◽  
F. S. Shaw
Keyword(s):  
Plastic Deformation ◽  
Stress Distribution ◽  
Numerical Solution ◽  
Rotational Symmetry ◽  
Relaxation Methods ◽  
Elastoplastic Boundary ◽  
Sufficient Magnitude ◽  
Elastoplastic Torsion ◽  
Von Mises

Abstract Using relaxation methods, an approximate numerical solution is found of the stress distribution in a shaft of rotational symmetry, which is subjected to a torque of sufficient magnitude to cause portions of the material to yield. It is assumed that the material of which the shaft is composed is isotropic and yields according to the condition of von Mises. The particular problem investigated is a shaft with a collar; results are presented showing the elastoplastic boundary, and the stress distribution, for two different amounts of plastic deformation.

Sign in / Sign up

Export Citation Format

Share Document