Hydraulic Versus Swage Autofrettage and Implications of the Bauschinger Effect

2003 ◽  
Vol 125 (3) ◽  
pp. 309-314 ◽  
Author(s):  
A. P. Parker ◽  
G. P. O’Hara ◽  
J. H. Underwood
Keyword(s):  
Residual Stresses ◽  
Experimental Evidence ◽  
Hybrid Method ◽  
Bauschinger Effect ◽  
Pressure Level ◽  
Opening Angle ◽  
Fatigue Lifetime ◽  
Analysis Of Results

A hybrid method is presented which permits calculation of residual stresses in a swage autofrettaged tube including Bauschinger effect. The results are generally supported by three types of available experimental evidence by comparing “equivalent” swage and hydraulic autofrettage tubes having the same level of overstrain. Radial slitting of the swaged tube is predicted to show a greater opening angle than its hydraulic equivalent. Fatigue lifetime of the swaged tube is predicted to be significantly higher than the hydraulic case. Re-pressurization of the equivalent tubes is predicted to produce initial re-yielding at the same pressure in both cases. Analysis of results shows that permanent strains in the swaged tube are expected to appear at a pressure level below that for the hydraulic tube.

A Re-Autofrettage Procedure for Mitigation of Bauschinger Effect in Thick Cylinders

2004 ◽  
Vol 126 (4) ◽  
pp. 451-454 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Yield Strength ◽  
Residual Stresses ◽  
Fracture Resistance ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Pressure Vessels ◽  
Fatigue Lifetime ◽  
Cyclic Pressure ◽  
Manufacturing Procedure ◽  
Tube Geometry

A manufacturing procedure for enhancing residual stresses and thereby improving fatigue lifetime and fracture resistance of pressure vessels is proposed. The procedure involves initial autofrettage; one or more “heat soak plus autofrettage” sequences and an optional final heat soak. Stresses are calculated numerically for traditional, single autofrettage and compared with those created by the new procedure. The loss of bore compressive hoop stress due to Bauschinger effect is predicted to be significantly reduced. Associated fatigue lifetime calculations indicate that life may be improved by a factor of between 2 and 30, depending upon tube geometry and the ratio of cyclic pressure to yield strength. Repeated overload plus heat soak cycles may also be of benefit in other engineering design scenarios.

A Re-Autofrettage Procedure for Mitigation of Bauschinger Effect in Thick Cylinders

2005 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Yield Strength ◽  
Residual Stresses ◽  
Fracture Resistance ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Pressure Vessels ◽  
Fatigue Lifetime ◽  
Cyclic Pressure ◽  
Manufacturing Procedure ◽  
Tube Geometry

A manufacturing procedure for enhancing residual stresses and thereby improving fatigue lifetime and fracture resistance of pressure vessels is proposed. The procedure involves initial autofrettage; one or more ‘heat soak plus autofrettage’ sequences and an optional final heat soak. Stresses are calculated numerically for traditional, single autofrettage and compared with those created by the new procedure. The loss of bore compressive hoop stress due to Bauschinger effect is predicted to be significantly reduced. Associated fatigue lifetime calculations indicate that life may be improved by a factor of between 2 and 30, depending upon tube geometry and the ratio of cyclic pressure to yield strength. Repeated overload plus heat soak cycles may also be of benefit in other engineering design scenarios.

Stress Concentration, Stress Intensity, and Fatigue Lifetime Calculations in Autofrettaged Tubes Containing Axial Perforations Within the Wall

1997 ◽  
Vol 119 (4) ◽  
pp. 488-493 ◽  
Author(s):  
A. P. Parker ◽  
S. N. Endersby ◽  
T. J. Bond ◽  
J. H. Underwood ◽  
S. L. Lee ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fe Analysis ◽  
Opening Angle ◽  
Experimental Investigations ◽  
Fatigue Lifetime ◽  
Stress Gradients ◽  
Elastic Plastic ◽  
Plain Tube ◽  
Hole Boundary

Elastic, elastic-plastic and experimental stress analyses, and fatigue lifetime predictions are presented for thick cylinders containing multiple, axial holes within the wall. The holes are generally semi-elliptical (including semi-circular), and the cylinders are autofrettaged after introduction of the holes and are subsequently subjected to cyclic pressurization of the bore. Two potentially critical failure locations are identified; a fracture-mechanics based design methodology is proposed; elastic and elastic-plastic finite element (FE) analyses are undertaken. The elastic FE analysis predicts hoop stresses at the bore resulting from internal pressurization which are some 7 percent higher than those for the equivalent plain tube. For a given hole size and location and for nominal overstrains of 40 percent or greater, the residual compressive stress at the bore is reduced by approximately 15 percent below the value for a plain tube of the same radius ratio. Two experimental investigations are reported, one based upon X-ray diffraction, to measure residual stresses and stress gradients, and the other based upon radial tube slitting, to measure opening angle. They confirm most features of the residual stress profiles predicted from FE analysis with the exception of high compressive residual stresses and stress gradients immediately adjacent to the hole boundaries. Appropriate use of the residual stress information permits prediction of tube lifetimes for cracks emanating from the bore and from the hole. For the geometry and loading under consideration, the more critical location is predicted to be the hole boundary, the lifetime for failures originating from this point being some 60 percent of the lifetime for cracks originating at the bore.

Failure Mechanisms of Particulate Two-Phase Composites

1998 ◽  
Vol 529 ◽  
Author(s):  
T. Antretter ◽  
E D. Fischer
Keyword(s):  
Residual Stresses ◽  
Crack Growth ◽  
Opening Angle ◽  
Geometrical Parameters ◽  
Two Phase ◽  
Absolute Size ◽  
The Matrix ◽  
Unit Cells ◽  
Angle Criterion ◽  
Probability Of Fracture

AbstractIn many composites consisting of hard and brittle inclusions embedded in a ductile matrix failure can be attributed to particle cleavage followed by ductile crack growth in the matrix. Both mechanisms are significantly sensitive towards the presence of residual stresses.On the one hand particle failure depends on the stress distribution inside the inclusion, which, in turn, is a function of various geometrical parameters such as the aspect ratio and the position relative to adjacent particles as well as the external load. On the other hand it has been observed that the absolute size of each particle plays a role as well and will, therefore, be taken into account in this work by means of the Weibull theory. Unit cells containing a number of quasi-randomly oriented elliptical inclusions serve as the basis for the finite element calculations. The numerical results are then correlated to the geometrical parameters defining the inclusions. The probability of fracture has been evaluated for a large number of inclusions and plotted versus the particle size. The parameters of the fitting curves to the resulting data points depend on the choice of the Weibull parameters.A crack tip opening angle criterion (CTOA) is used to describe crack growth in the matrix emanating from a broken particle. It turns out that the crack resistance of the matrix largely depends on the distance from an adjacent particle. Residual stresses due to quenching of the material tend to reduce the risk of particle cleavage but promote crack propagation in the matrix.

Finite Element Analysis of Residual Stresses in Threaded End Closures

1991 ◽  
Vol 113 (3) ◽  
pp. 398-401 ◽  
Author(s):  
A. Chaaban ◽  
U. Muzzo
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Bauschinger Effect ◽  
High Stress ◽  
Empirical Method ◽  
Pressure Vessels ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Proof Testing ◽  
Pressure Cycle

Due to the high stress concentration at the root of the first active thread in threaded end closures of high pressure vessels, yielding may occur in this region during the application of the first pressure cycle or proof testing. This overstraining introduces residual stresses that influence the fatigue performance of the vessel. This paper presents a parametric analysis of threaded end closures using elastic and elasto-plastic finite element solutions. The results are used to discuss the influence of these residuals on the estimated fatigue life when the vessel is subjected to repeated internal pressure. A simple empirical method to allow for the Bauschinger effect of the material is also proposed.

scholarly journals Multi-sector approximation method for arteries: the residual stresses of circumferential rings with non-trivial openings

2019 ◽  
Vol 16 (156) ◽  
pp. 20190023 ◽  
Author(s):  
Taisiya Sigaeva ◽  
Michel Destrade ◽  
Elena S. Di Martino
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Inverse Problem ◽  
Residual Stresses ◽  
Opening Angle ◽  
Circular Sector ◽  
Ring Configuration ◽  
Closed Ring ◽  
Angle Method ◽  
Pathological Tissues

The opening angle method is a popular choice in biomechanics to estimate residual stresses in arteries. Experimentally, it means that an artery is cut into rings; then the rings are cut axially or radially allowing them to open into sectors; finally, the corresponding opening angles are measured to give residual stress levels by solving an inverse problem. However, for many tissues, for example in pathological tissues, the ring does not open according to the theory into a neat single circular sector, but rather creates an asymmetric geometry, often with abruptly changing curvature(s). This phenomenon may be due to a number of reasons including variation in thickness, microstructure, mechanical properties, etc. As a result, these samples are often eliminated from studies relying on the opening angle method, which limits progress in understanding and evaluating residual stresses in real arteries. With this work, we propose an effective approach to deal with these non-trivial openings of rings. First, we digitize pictures of opened rings to split them into multiple, connected circular sectors. Then we measure the corresponding opening angles for each sub-sector. Subsequently, we can determine the residual stresses for individual sectors in a closed-ring configuration and, thus, approximate the circumferential residual bending effects.

scholarly journals Anisotropic residual stresses in arteries

2019 ◽  
Vol 16 (151) ◽  
pp. 20190029 ◽  
Author(s):  
Taisiya Sigaeva ◽  
Gerhard Sommer ◽  
Gerhard A. Holzapfel ◽  
Elena S. Di Martino
Keyword(s):  
Experimental Data ◽  
Residual Stresses ◽  
Abdominal Aorta ◽  
Strain Energy Function ◽  
Opening Angle ◽  
Link Type ◽  
Residual Deformations ◽  
Angle Method ◽  
The Individual

The paper provides a deepened insight into the role of anisotropy in the analysis of residual stresses in arteries. Residual deformations are modelled following Holzapfel and Ogden (Holzapfel and Ogden 2010, J. R. Soc. Interface 7 , 787–799. ( doi:10.1098/rsif.2009.0357 )), which is based on extensive experimental data on human abdominal aortas (Holzapfel et al. 2007, Ann. Biomed. Eng. 35 , 530–545. ( doi:10.1007/s10439-006-9252-z )) and accounts for both circumferential and axial residual deformations of the individual layers of arteries—intima, media and adventitia. Each layer exhibits distinctive nonlinear and anisotropic mechanical behaviour originating from its unique microstructure; therefore, we use the most general form of strain-energy function (Holzapfel et al. 2015, J. R. Soc. Interface 12 , 20150188. ( doi:10.1098/rsif.2015.0188 )) to derive residual stresses for each layer individually. Finally, the systematic experimental data (Niestrawska et al. 2016, J. R. Soc. Interface 13 , 20160620. ( doi:10.1098/rsif.2016.0620 )) on both mechanical and structural properties of the different layers of the human abdominal aorta facilitate our discussion on (i) the importance of anisotropy in modelling residual stresses; (ii) the variability of residual stresses within the same class of tissue, the abdominal aorta; (iii) the limitations of conventional opening angle method to account for complex residual deformations; and (iv) the effect of residual stresses on the loaded configuration of the aorta mimicking in vivo conditions.

An analysis of shot peening

1983 ◽  
Vol 18 (2) ◽  
pp. 95-100 ◽  
Author(s):  
D A Hills ◽  
R B Waterhouse ◽  
B Noble
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Experimental Evidence ◽  
Contact Pressure ◽  
Shot Peening ◽  
Pressure Loading ◽  
The Relationship

It is shown that the residual stresses obtained during shot-peening are directly proportional to the treated material's hardness, and that the depth of material influenced depends on the velocity of approaching shot. The relationship between the shot size and depth hardened is developed, and experimental evidence is provided to verify the major points of the analysis. Useful curves, enabling the variation of residual stress with depth to be estimated, are included, and this enables the shot-peening treatment to be matched to alleviate any subsequent contact-pressure loading that the material may experience during service.

Application of Finite Element Analysis for the Prediction of the Fatigue Lifetime of Spot Welds with Triple SPCC plates

2007 ◽  
Vol 345-346 ◽  
pp. 1453-1456
Author(s):  
Byoung Ho Choi ◽  
Dong Ho Joo ◽  
Sam Hong Song
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shell Model ◽  
Crack Opening ◽  
Equivalent Stress ◽  
Shear Loading ◽  
Opening Angle ◽  
Element Analysis ◽  
Fatigue Lifetime ◽  
Empirical Prediction

The fatigue characteristic of triple spot welded SPCC plates with the variation of the thickness and the geometry under tensile-shear loading is studied by finite element analysis (FEA) and the obtained data is compared with experimental data. Using 3-D solid element model and 3-D beam-shell model, the maximum equivalent stress and the beam deformation angle (BDA) for various thickness and geometry is studied. The linear relation between crack opening angle (COA) from experiment and the BDA from FEA for beam-shell model is represented, and the empirical prediction of fatigue lifetime is proposed using the relation between COA and BDA.

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