Effect of Reverse Yielding on the Residual Contact Pressure in Tube-to-Tubesheet Joints

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Mehdi Kazeminia
Keyword(s):  
Finite Elements ◽  
Contact Pressure ◽  
Deformation Theory ◽  
Material Behavior ◽  
Analytical Prediction ◽  
Hardening Material ◽  
Expansion Pressure ◽  
Reverse Yielding ◽  
Materials Used ◽  
Von Mises

The analytical prediction of the contact stress in tube-to-tubesheet joints subjected to hydraulic expansion is conducted without any consideration to reverse yielding that can occur inside the tube. Most existing models consider the tube and tubesheet to unload elastically when the expansion pressure is released. These models are therefore less conservative as they overestimate the contact pressure. An analytical model that considers strain-hardening material behavior of the tube and tubesheet and accounts for reverse yielding has been developed. The model is based on Henckey deformation theory and the Von Mises yield criteria. The paper shows that reverse yielding that is present in tubes during hydraulic expansion unloading makes the joint less rigid and causes a decrease in the contact pressure depending on the gap clearance and the materials used. A good correlation between the analytical and finite elements results is obtained on different treated cases which gives confidence on the developed model.

Effect of Reverse Yielding on the Residual Contact Stresses of Tube-to-Tubesheet Joints Subjected to Hydraulic Expansion

2015 ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Mehdi Kazeminia
Keyword(s):  
Contact Pressure ◽  
Contact Stress ◽  
Deformation Theory ◽  
Material Behavior ◽  
Analytical Prediction ◽  
Hardening Material ◽  
Expansion Pressure ◽  
Reverse Yielding ◽  
Materials Used ◽  
Von Mises

The analytical prediction of the contact stress in tube-to-tubesheet joints subjected to hydraulic expansion is conducted without any consideration to reverse yielding that can occur inside the tube. Most existing models consider the tube and tubesheet to unload elastically when the expansion pressure is released. These models are therefore less conservative as the overestimate the contact pressure. An analytical model that considers strain-hardening material behavior of the tube and tubesheet and accounts for reverse yielding has been developed. The model is based on Henckey deformation theory and the Von Mises yield criteria. The paper shows that reverse yielding that is present in tubes during hydraulic expansion unloading makes the joint less rigid and causes a decrease in the contact pressure depending on the gap clearance and the materials used. A good correlation between the analytical and FEM results is obtained on different treated cases which gives confidence on the developed model.

Impact of Grooves in Hydraulically Expanded Tube-to-Tubesheet Joints

2020 ◽  
Author(s):  
Dinu Thomas Thekkuden ◽  
Abdel-Hamid I. Mourad ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Pressure ◽  
Equivalent Stress ◽  
Pull Out ◽  
Expansion Pressure ◽  
Loading And Unloading ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Maximum Contact ◽  
Pull Out Strength

Abstract The stress corrosion cracking of tube-to-tubesheet joints is one of the major faults causing heat exchanger failure. After the expansion process, the stresses are developed in a plastically deformed tube around the tube-to-tubesheet joint. These residual stressed joints, exposed to tube and shell side fluids, are the main crack initiation sites. Adequate contact pressure at the tube-to-tubesheet interface is required to produce a quality joint. Insufficient tube-to-tubesheet contact pressure leads to insufficient joint strength. Therefore, a study on the residual stress and contact pressure that have a great significance on the quality of the tube-to-tubesheet joint is highly demanded. In this research, a 2D axisymmetric numerical analysis is performed to study the effect of the presence of grooves in the tubesheet and the expansion pressure length on the distribution of contact pressure and stress during loading and unloading of 400 MPa expansion pressure. The results show that the maximum contact pressure is independent of the expansion pressure length. However, the presence of grooves significantly increased the maximum contact pressure. It is proven that the presence of grooves in the tubesheet is distinguishable from the maximum contact pressure and residual von mises equivalent stress. The tube pull-out strength increases with the expansion pressure and the number of grooves. In conclusion, the presence of the grooves affects the tube-to-tubesheet joints.

THE BAUSCHINGER AND HARDENING EFFECT ON RESIDUAL STRESSES IN THICK-WALLED CYLINDERS OF SUS 304

2003 ◽  
Vol 26 (4) ◽  
pp. 361-372
Author(s):  
A. Ghorbanpour ◽  
A. Loghman ◽  
H. Khademizadeh ◽  
M. Moradi
Keyword(s):  
Numerical Model ◽  
Residual Stresses ◽  
Yield Criterion ◽  
Material Model ◽  
304 Stainless Steel ◽  
Hardening Material ◽  
Effect Factor ◽  
Reverse Yielding ◽  
Von Mises Yield Criterion ◽  
Von Mises

A thick-walled cylinder of strain hardening material with closed ends, which is assumed to obey Von-Mises yield criterion is considered. An elastoplastic and residual stress analysis of thick-walled cylinders is performed with the incremental theory of plasticity. Critical pressures of direct and reverse yielding are investigated using the Von-Mises yield criterion as well as the Bauschinger effect factor (BEF). The material selected is SUS 304 stainless steel. The material's loading and unloading properties including the (BEF) are obtained experimentally and represented mathematically as a continuous function of effective plastic strain. The material model and the BEF have been incorporated in an analytical-numerical model so as to predict the cylinders plastic and residual stresses as well as the critical pressures of direct and reverse yielding. The analytical-numerical model for the prediction of critical inner pressure, plastic stress distributions and the subsequent residual stresses of thick-walled cylinders is validated by using experimental results. Residual stresses with and without the BEF are obtained and the corresponding results are compared. In the case study of a specific cylinder (Radii ratio of β=2), it has been concluded that residual stresses subsequent to a 45% overstrained condition are at the onset of reverse yielding when the BEF is considered.

scholarly journals Elastic-Plastic Stresses in Shrink Fit with A Solid Shaft

2019 ◽  
Vol 286 ◽  
pp. 02001
Author(s):  
Amal Mouâa ◽  
Nor Eddine Laghzale ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Pressure ◽  
Gas Turbines ◽  
Accurate Estimate ◽  
Material Behavior ◽  
Analytic Method ◽  
Plastic Range ◽  
Hardening Material ◽  
Elastic Plastic ◽  
Shrink Fit ◽  
Distribution Of Stresses

Shrink fit joining a solid shaft and a cylinder requires an accurate estimate of the residual contact pressure to transmit high powers, as in the case of gas turbines. Such torques require deformations of materials beyond their elastic limits. This paper presents an analytical model that analyses the stresses in a shrink fit assembly consisting of a solid shaft and a cylindrical hub operating in the elastic-plastic range. Assuming the hub to have a nonlinear work-hardening material behavior, the distribution of stresses as functions of the interference, and the effect of geometry on contact pressure and on interference are exhibited. To validate the analytic method, Finite Element Method was used.

Loading and Unloading of Thick-Walled Cylindrical Pressure Vessels of Strain-Hardening Material

1994 ◽  
Vol 116 (2) ◽  
pp. 105-109 ◽  
Author(s):  
A. Loghman ◽  
M. A. Wahab
Keyword(s):  
Residual Stresses ◽  
Strain Hardening ◽  
Yield Criterion ◽  
Strain Curve ◽  
Pressure Vessels ◽  
Critical Conditions ◽  
Hardening Material ◽  
Wide Range ◽  
Reverse Yielding ◽  
Von Mises

A thick-walled closed-end cylinder of isotropic, homogeneous and strain-hardening material is considered in this study. Loading is assumed to consist of a temperature gradient as well as an internal pressure. Unloading is completely elastic without considering a Bauschinger effect. A generalized plane strain case in which the material obeys Von Mises yield criterion is studied. Using the yield criterion, critical conditions for a wide range of loading combinations and thickness ratios are investigated. After the critical condition is established, load is increased beyond the critical values and calculations are made for plastic stresses and strains and progress of plastic zone using an incremental theory of plasticity. Residual stresses are obtained as the cylinder is unloaded from a 25 and 50-percent overstrained condition. Reverse yielding is not considered while the residual stresses at the onset of reverse yielding are calculated. Loading function is assumed to follow the stress-strain curve of SUS 304 at a constant temperature of 400°C, which is selected from the experimental work of earlier researchers.

Determination of Expanding Pressure of Hydraulically Expanded Tube-to-Tubesheet Joint

2010 ◽  
Vol 97-101 ◽  
pp. 2898-2902 ◽  
Author(s):  
Xie Tian ◽  
Xiao Ping Huang ◽  
Zhi Yong Fu
Keyword(s):  
Strain Hardening ◽  
Contact Pressure ◽  
Material Model ◽  
Linear Strain ◽  
Element Analysis ◽  
Hardening Material ◽  
Expansion Pressure ◽  
General Strain ◽  
Special Case

It is very important to determine the expansion pressure or residual contact pressure of tube-to-tubesheet joint. The expansion pressure and the residual contact pressure are affected by the geometry, material mechanical properties of the tube and tubesheet. In the basic theory of calculating the residual contact pressure of tube-to-tubesheet joints, the elastic-perfectly material is assumed. Because of the strain-hardening of the materials, linear strain-hardening or power strain-hardening were adopted in some analyzing models of the hydraulically expanded tube-to-tubesheet joint. In this paper, a general strain-hardening material model is adopted and an analytical model is proposed and validated by finite element analysis results. The elastic-perfectly model, linear strain-hardening model or power strain-hardening can be the special case of the present model.

Theoretical Analysis of Hydraulically Expanded Tube-to-Tubesheet Joints With Linear Strain Hardening Material Behavior

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Nor Eddine Laghzale ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Strain Hardening ◽  
Material Behavior ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Hardening Material ◽  
Perfectly Plastic ◽  
Expansion Pressure ◽  
Proper Material ◽  
Elastic Perfectly Plastic ◽  
Design Calculations

The mechanism of failure of tube-to-tubesheet joints is related to the level of stresses produced in the tube expansion and transition zones during the expansion process. Maintaining a lower bound limit of the initial residual contact pressure over the lifetime of the expanded joint is a key solution to a leak free joint. An accurate model that estimates these stresses can be a useful tool to the design engineer to select the proper material geometry combination in conjunction with the required expansion pressure. Most existing design calculations are based on an elastic perfectly plastic behavior of the expansion joint materials. The proposed model is based on a strain hardening with a bilinear material behavior of the tube and the tubesheet. The interaction of these two components is simulated during the whole process of the application of the expansion pressure. The effects of the gap and the material strain hardening are to be emphasized. The model results are validated and confronted against the more accurate numerical finite element analysis models. Additional comparisons have been made to existing methods.

An Analytical Solution of Hydraulically Expanded Tube-to-Tubesheet Joints With Linear Strain Hardening Material Behaviour

2008 ◽  
Author(s):  
Nor Eddine Laghzale ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Strain Hardening ◽  
Material Behavior ◽  
Plastic Behavior ◽  
Hardening Material ◽  
Whole Process ◽  
Perfectly Plastic ◽  
Expansion Pressure ◽  
Proper Material ◽  
Elastic Perfectly Plastic ◽  
Design Calculations

The mechanism of failure of tube-to-tubesheet joints is related to the level of stresses produced in the tube expansion and transition zones during the expansion process. Maintaining a lower bound limit of the initial residual contact pressure over the lifetime of the expanded joint is a key solution to a leak free joint. An accurate model that estimates these stresses can be a useful tool to the design engineer to select the proper material geometry combination in conjunction with the required expansion pressure. Most existing design calculations are based on an elastic perfectly plastic behavior of the expansion joint materials. The proposed model is based on a strain hardening with a bilinear material behavior of the tube and the tubesheet. The interaction of these two components is simulated during the whole process of the application of the expansion pressure. The effects of the gap and the material strain hardening will be emphasized. The model results are validated and confronted against the more accurate numerical FEA models. Additional comparisons have been made to existing methods.

Elastoplastic Stress Study in Thick-Walled Spherical Vessels Considering Finite Deformation

2006 ◽  
Author(s):  
Hossein Darijani ◽  
Reza Naghdabadi ◽  
Nima Shamsaei ◽  
Mehdi Danesh Sararoudi
Keyword(s):  
Present Method ◽  
Deformation Theory ◽  
Hardening Material ◽  
Material Parameters ◽  
Stress Study ◽  
Hyper Elastic ◽  
Linear And Nonlinear ◽  
Analytical Result ◽  
Von Mises ◽  
Nonlinear Hardening

An exact elasto-plastic analytical solution for large-strained internal pressurized thick-walled spherical vessels made of elastic-linear and nonlinear hardening material is derived in this paper. This solution is based on the notion of finite strains, the deformation theory of Hencky and the yield criteria of von Mises and Tresca. Nolinear elastic solution of an axisymetric boundary value problem is used as a basis to generate its inelastic solution, whereas the Hyper-elastic constitutive equation is invoked to represent the material response in the elastic region. This method treats the material parameters as field variables. Their distributions are obtained in an iterative manner using Nuber’s rule. Obtained Results for stress distribution using the present method shown are in excellent agreement with only analytical result which has been determined in the case of isochoric volume.

An Experimental Investigation of the Yield Loci of 1100-0 Aluminum, 70:30 Brass, and an Overaged 2024 Aluminum Alloy After Various Prestrains

1986 ◽  
Vol 108 (4) ◽  
pp. 313-320 ◽  
Author(s):  
D. E. Helling ◽  
A. K. Miller ◽  
M. G. Stout
Keyword(s):  
Aluminum Alloy ◽  
Small Strain ◽  
Yield Locus ◽  
Material Behavior ◽  
Shear Stresses ◽  
2024 Aluminum Alloy ◽  
Yield Loci ◽  
Aluminum Alloy 2024 ◽  
Von Mises ◽  
Normal And Shear Stresses

The multiaxial yield behaviors of 1100-0 aluminum, 70:30 brass, and an overaged 2024 aluminum alloy (2024-T7) have been investigated for a variety of prestress histories involving combinations of normal and shear stresses. Von Mises effective prestrains were in the range of 1.2–32%. Prestress paths were chosen in order to investigate the roles of prestress and prestrain direction on the nature of small-strain offset (ε = 5 × 10−6) yield loci. Particular attention was paid to the directionality, i.e., translation and distortion, of the yield locus. A key result, which was observed in all three materials, was that the final direction of the prestrain path strongly influences the distortions of the yield loci. Differences in the yield locus behavior of the three materials were also observed: brass and the 2024-T7 alloy showed more severe distortions of the yield locus and a longer memory of their entire prestrain history than the 1100-0 aluminum. In addition, more “kinematic” translation of the subsequent yield loci was observed in brass and 2024-T7 than in 1100-0 aluminum. The 2024-T7 differed from the other materials, showing a yield locus which decreased in size subsequent to plastic straining. Finally, the implications of these observations for the constitutive modeling of multiaxial material behavior are discussed.

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