Effects of Initial Tube-Tubesheet Clearance and Grooves on Axial and Hoop Residual Stresses of Roller Expanded Joints

2010 ◽  
Author(s):  
A. N. Shuaib ◽  
O. M. Duffuaa ◽  
N. Merah ◽  
Y. Al-Nassar
Keyword(s):  
Residual Stresses ◽  
Hoop Stress ◽  
Axial Stress ◽  
Element Model ◽  
Radial Clearance ◽  
Radial Deformation ◽  
Initiation And Propagation ◽  
Hoop Stresses ◽  
Corrosive Environments ◽  
Degrees Of Severity

An axisymmetric finite element model is used to evaluate the effect of large initial tube-tubesheet radial clearance and the effect of grooves machined in the tubesheet hole on the distributions and magnitudes of the radial deformation of expanded tube walls, residual contact stress, residual hoop stress, and residual axial stress along the expanded length of the tube and in the transition zone. The results have revealed the presence of residual axial stresses and residual hoop stresses in the inside and outside surfaces of the tubes with various degrees of severity. These tensile residual stresses may cause crack initiation and propagation and may lead stress corrosion cracking in corrosive environments.

Residual Stresses in Roller Expanded Tube-Tubesheet Joints With Large Initial Clearance and Grooves

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
A. N. Shuaib ◽  
O. M. Duffuaa ◽  
N. Merah ◽  
Y. Al-Nassar
Keyword(s):  
Residual Stresses ◽  
Transition Zone ◽  
Fatigue Crack Initiation ◽  
Element Model ◽  
Radial Clearance ◽  
Radial Deformation ◽  
Initial Clearance ◽  
Hoop Stresses ◽  
Degrees Of Severity ◽  
Exchanger Tube

Heat exchanger tube rolling introduces tensile residual stresses in the expanded part of the tube and the transition zone between the expanded and unexpanded regions of the tube. These tensile residual stresses accelerate fatigue crack initiation and enhance small crack propagation and may cause stress corrosion cracking of the tube if it is exposed to a corrosive environment. In this paper, an axisymmetric finite element model has been used to evaluate the effect of large initial tube-tubesheet radial clearance and to evaluate the effects of grooves machined in the tubesheet hole on the distributions and magnitudes of the radial deformation of tube walls and the residual stresses along the expanded length of the tube and in the transition zone. The results have revealed the presence of tensile and compressive residual axial and hoop stresses in the inner and outer surfaces of the tubes with various degrees of severity.

Relaxation of Residual Stresses in and around Mechanical Fasteners Due to Fatigue Loading

2006 ◽  
Vol 524-525 ◽  
pp. 153-158 ◽  
Author(s):  
Matthew E. Fox ◽  
Philip J. Withers
Keyword(s):  
Residual Stresses ◽  
Hoop Stress ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Far Field ◽  
Synchrotron Diffraction ◽  
Fastener Hole ◽  
Single Plate ◽  
Mechanical Fasteners ◽  
Hoop Stresses

The residual stresses around clearance-fit mechanical fasteners have been found to be similar to those around cold expanded holes where compressive hoop stresses close to the fastener hole are balanced by far-field tensile stresses. This compressive zone has been shown to prolong fatigue lifetimes around fastener holes. Constant amplitude fatigue loading was applied to single plate rivet specimens for varying numbers of cycles to investigate the redistribution of these stresses after fatiguing. Synchrotron diffraction was used to map the evolution of the residual stresses around the rivets. Little change in the hoop stress local to the rivets occurred until visible fatigue cracks were observed suggesting that relaxation of these stresses is due to the cracks rather than their cause.

The Influence of Geometrical Distortions of Three-Dimensional Finite Elements, Used to Model Proximal Femoral Bone

1995 ◽  
Vol 209 (1) ◽  
pp. 31-36 ◽  
Author(s):  
J Vander Sloten ◽  
G van der Perre
Keyword(s):  
Proximal Femur ◽  
Hoop Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Bending Stress ◽  
Different Types ◽  
Dimensional Finite Element ◽  
Middle Node ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses

A realistic three-dimensional finite element model of the proximal femur requires the use of irregularly shaped elements to represent this geometry, unless the geometry is considerably simplified. The authors have investigated the influence of different types of element distortions upon the accuracy of two stresses which are relevant in the proximal femur: the bending stress and the tangential (hoop) stress. While most angular and geometric distortions did not influence the bending stress significantly, the position of the middle node on the edge of a quadratic element was very critical, as were some types of element skewness. The hoop stresses can only be calculated accurately if the geometry is modelled as well as possible by a cylinder, and not by a cone.

Investigation of the Biaxial Behaviour of 316 Stainless Steel Based on Critical Plane Method

2018 ◽  
Vol 774 ◽  
pp. 510-515
Author(s):  
A.S. Cruces ◽  
Pablo Lopez-Crespo ◽  
Belen Moreno ◽  
S. Bressan ◽  
Takamoto Itoh
Keyword(s):  
Stainless Steel ◽  
Hoop Stress ◽  
Axial Stress ◽  
Critical Plane ◽  
316 Stainless Steel ◽  
Dog Bone ◽  
Critical Plane Approach ◽  
Hoop Stresses ◽  
Life Predictions ◽  
Biaxial Behavior

In this work the biaxial behavior of 316 stainless steel is studied under the lens of critical plane approach. A series of ten experiments were developed on dog bone shape hollow cylindrical specimens made of type 316 stainless steel. Five different loading conditions were assessed, with (i) only axial stress, (ii) only hoop stress, (iii) proportional combination of axial and hoop stresses, (iv) non-proportional combination of axial and hoop stresses with square shape and (v) non-proportional combination of axial and hoop stresses with L-shape. The fatigue analysis is performed following four different critical plane theories, namely Wang-Brown, Fatemi-Socie, Liu I and Liu II. The efficiency of all four theories is studied in terms of the accuracy of their life predictions.

Investigation of Residual Stress Development During Swage Autofrettage, Using Finite Element Analysis

2009 ◽  
Author(s):  
Michael C. Gibson ◽  
Amer Hameed ◽  
John G. Hetherington
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Axial Stress ◽  
Slope Angle ◽  
Subsequent Development ◽  
Element Model ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Reverse Yielding

Swaging is one method of autofrettage, a means of pre-stressing high-pressure vessels to increase their fatigue lives and load bearing capacity. Swaging achieves the required deformation through physical interference between an oversized mandrel and the bore diameter of the tube, as it is pushed through the tube. A Finite Element model of the swaging process was developed, in ANSYS, and systematically refined, to investigate the mechanism of deformation and subsequent development of residual stresses. A parametric study was undertaken, of various properties such as mandrel slope angle, parallel section length and friction coefficient. It is observed that the axial stress plays a crucial role in the determination of the residual hoop stress and reverse yielding. The model, and results obtained from it, provides a means of understanding the swaging process and how it responds to different parameters. This understanding, coupled with future improvements to the model, potentially allows the swaging process to be refined, in terms of residual stresses development and mandrel driving force.

A Limiting Defect Study of an Elbow

2011 ◽  
Author(s):  
Jinhua Shi ◽  
David Blythe
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Hoop Stress ◽  
Defect Size ◽  
Welding Residual Stress ◽  
Central Section ◽  
Butt Welding ◽  
Wide Range ◽  
Stress Components ◽  
Hoop Stresses

In order to ensure the integrity of a seamless butt-welding elbow, both the central section and ends of the elbow need to be assessed, as the maximum stress is normally located at the central section of the elbow but there are no welding residual stresses. Furthermore, at the ends (welds) of the elbow, very high welding residual stresses exist if the welds have not been post weld heat treated but the primary stresses induced by the internal pressure and system moments are lower. For a 90 degree elbow welded to seamless straight pipe, both maximum axial and hoop stress components in the elbow can be calculated using ASME III NB-3685. At the ends of the elbow, axial and hoop stress components can be obtained using the stress equations presented in the paper of PVP2010-25055. In this paper, a series of limiting defect assessments have been carried out on an elbow assuming a postulated axial external defect as follows: • A number of assessments have been conducted directly using the axial and hoop stresses calculated based on ASME III NB-3685 for different system moments. • A series of assessments have been carried out using the axial and hoop stresses calculated using the stress equations presented in the paper of PVP2010-25055, a wide range of welding residual stresses and different system moments. A comparison of the assessment results in the elbow and at the ends of the elbow shows that when system moments are relatively low and the welding residual stress is high, the limiting defect size is located at the ends of the elbow; when the system moments are high and the welding residual stress is low the limiting defect size is located at the central section of the elbow. Therefore, it can be concluded that when assessing an elbow, the assessments should be carried out at both the central section and the ends of the elbow, in order to ensure the integrity of the elbow.

Effects of Pipe Dimensions and Outer Surface-Buttering Weld Conditions on Residual Stress Distributions

2008 ◽  
Author(s):  
Nobuyoshi Yanagida
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Hoop Stress ◽  
Axial Stress ◽  
Butt Joint ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Butt Joints ◽  
Inner Surface

Effects of pipe dimensions and outer surface-buttering weld conditions on residual stress distributions were evaluated using the finite element method. Residual stresses were analyzed for 508–mm-diameter (500A) pipe 38.1 mm thick, 508–mm-diameter (500A) pipe 15.1 mm thick, and 267–mm-diameter (250A) pipe 15.1 mm thick. After the residual stresses at pipe butt joints were analyzed, residual stresses at these joints subjected to the outer surface-buttering welds were analyzed. Residual stresses were determined for various weld widths, thicknesses, and heat inputs. These analyses indicate that tensile axial stress occurred at inner surface of the pipe butt joint and that it decreased with increasing the outer surface buttering-weld width or heat input. They also indicate that compressive hoop stress occurred at inner surface of the joint and that outer surface-buttering weld increased it. The outer surface-buttering weld conditions that generate compressive residual stress at the inner surface of the pipe butt joints were determined.

Wheel Rim Axial Residual Stress and a Proposed Mechanism for Vertical Split Rim Formation

2011 ◽  
Author(s):  
Cameron Lonsdale ◽  
John Oliver
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Axial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Axial Residual Stress ◽  
Railroad Wheels ◽  
Hoop Stresses ◽  
Future Work

Railroad wheels are manufactured with beneficial residual compressive hoop stresses, which are imparted by rim quenching and tempering. Hoop and radial residual stresses for wheels have been studied in detail by various organizations over the years and are relatively well characterized. However axial residual stresses, in the orientation across the rim width from back rim face to front rim face, have not been extensively investigated. This paper describes a failure mode known as a vertical split rim (VSR) and describes efforts to measure the axial residual stresses in, 1) new wheels, 2) service worn wheels and 3) wheels that have failed from VSRs. Initial axial residual stress measurement efforts, using core drilling and x-ray diffraction from the tread surface, are briefly reviewed. Further more extensive work using x-ray diffraction to measure axial residual stress on radial wheel slices is described and data are presented, focusing on differences between the three wheel types. The concept of Axial Stress Amplification (ASA) is outlined, and the relationship of axial residual stress to VSRs is discussed. A proposed mechanism for VSR formation is described. Future work, with a goal of reducing or eliminating VSRs in service, is considered.

Measurement of Residual Hoop Stresses in Cylinders Using the Compliance Method

1986 ◽  
Vol 108 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Weili Cheng ◽  
Iain Finnie
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Hoop Stress ◽  
Axial Stress ◽  
Hole Drilling ◽  
Residual Stress Field ◽  
Axial Coordinate ◽  
X Ray ◽  
Axial Crack ◽  
Hoop Stresses

A method is proposed for measurement of the hoop stress in an axisymmetric residual stress field in cylinders in which the axial stress is independent of the axial coordinate. The method involves measuring strains at the outside surface while an axial crack is cut progressively from the outside. Experimental results are presented for two short cylindrical rings cut from a long quenched cylinder. Good general agreement is obtained with X-ray and hole drilling measurements of residual stresses.

The Single Slice Method for Measurement of Axisymmetric Residual Stresses in Solid Rods or Hollow Cylinders in the Region of Plane Strain

1998 ◽  
Vol 120 (2) ◽  
pp. 170-176 ◽  
Author(s):  
Weili Cheng ◽  
lain Finnie
Keyword(s):  
Residual Stresses ◽  
Plane Strain ◽  
Experimental Approach ◽  
Axial Stress ◽  
Strain Gages ◽  
Experimental Procedure ◽  
Thin Slice ◽  
Hollow Cylinders ◽  
Slice Method ◽  
Hoop Stresses

A new method is presented for the measurement of axisymmetric residual stresses in a solid rod or hollow cylinder in the region which is in a state of plane strain. The experimental procedure involves, first, making a complete transverse cut, normal to the axis of the part in the region which is initially in plane strain. Next, a number of strain gages are mounted on one of the faces produced by the first cut. A second transverse cut, parallel to the first, is then made to remove a thin slice containing the strain gages. It is shown that the change in strain gage readings due to removal of the slice may be used to deduce the axial stress in plane strain at the location of the first cut. The hoop stresses in the thin slice, which is in a state of plane stress, are readily obtained from the “crack compliance” procedure which we have described in earlier work. From this information and the initial axial stress in plane strain it is shown that the initial hoop and radial stresses in plane strain may be determined. The method is validated by obtaining the stresses in a water quenched rod which are shown to be in excellent agreement with those measured using a different experimental approach. Since the method does not require the measurement to be carried out on the original rod or cylinder, it allows the original residual stresses to be measured from a fractured shaft by making a slice near the plane of the fracture if the fracture is dominated by elastic deformation.

Sign in / Sign up

Export Citation Format

Share Document