Analysis of Residual Stress in the Rotational Autofrettage of Thick-Walled Disks

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
S. M. Kamal
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Circular Disk ◽  
Flow Rule ◽  
Plane Stress Condition ◽  
Radial Temperature ◽  
Fem Validation ◽  
Compressive Residual Stresses

Autofrettage is a means of generating compressive residual stresses at the inner side of a thick-walled cylinder or hollow disk by causing nonhomogeneous plastic deformation of the material at the inner side. The presence of residual compressive stresses at the inner region of the cylinder/disk enhance the pressure withstanding capacity, fatigue life and the resistance to stress corrosion cracking of the component. Despite the hydraulic and swage autofrettage are the widely practiced processes in industries, there are certain disadvantages associated with these processes. In view of this, in the recent years, researchers have proposed new methods of achieving autofrettage. Rotational autofrettage is such a recently proposed autofrettage method for achieving the beneficial compressive residual stresses in the cylinders. In the present work, the rotational autofrettage is studied for a thick-walled hollow circular disk. A theoretical analysis of the residual stresses produced in the disk after unloading are obtained assuming plane stress condition, Tresca yield criterion and its associated flow rule. The analysis takes into account the effect of strain hardening during plastic deformation. Further, the effect of residual stresses in the typical SS304 and aluminum disk is studied by subjecting them into three different types of loads viz., internal pressure, radial temperature difference, and rotational speed individually. A three-dimensional (3D) finite element method (FEM) validation of the theoretical stresses during rotational autofrettage of a disk is also presented.

Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents

2018 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Rick Wang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain History ◽  
Deformation History ◽  
Stress Strain ◽  
Element Analysis ◽  
Fea Model

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results. To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.

The Effect of Several Finishing Processes on the Fatigue Resistance of Hole Surfaces

1989 ◽  
Vol 111 (1) ◽  
pp. 71-73 ◽  
Author(s):  
M. O. Lai ◽  
A. Y. C. Nee
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Fatigue Resistance ◽  
Radial Direction ◽  
Fatigue Loading ◽  
Steel Plates ◽  
Finishing Processes ◽  
Compressive Residual Stresses

This investigation examines the effects of different finishing processes on the fatigue life of premachined holes in Assab 760 steel plates. The finishing processes studied were reaming, ballizing, and emery polishing. A general decrease in fatigue life with increase in surface roughness is observed for all the processes employed. In comparing the different processes, for a constant surface roughness, polishing is generally found to give the longest fatigue life while ballizing, in spite of the greater compressive residual stresses induced on the surface of the finished hole, the shortest. The surprising phenomenon was found to be attributed to the amount of plastic deformation occurred before fatigue loading. For Assab 760 steel, a prestrain in the radial direction of less than about 2.5 percent appeared to reduce the fatigue resistance of the material.

Characterization of the Residual Stresses in Plastically Deformed Ferrite-Martensite Steels Using Barkhausen Noise Measurements

2005 ◽  
Vol 500-501 ◽  
pp. 655-662 ◽  
Author(s):  
Xavier Kleber ◽  
Aurélie Hug-Amalric ◽  
Jacques Merlin
Keyword(s):  
Plastic Deformation ◽  
Tensile Stress ◽  
Residual Stresses ◽  
Barkhausen Noise ◽  
Opposite Behavior ◽  
Noise Measurements ◽  
Two Phases ◽  
Noise Signature ◽  
Compressive Residual Stresses

In this work, we show that the measurement of the Barkhausen noise allows the residual stresses in each of the two phases of ferrite-martensite steels to be characterized. We have first studied the effect of a tensile and a compressive stress on the Barkhausen noise signature. We observed that for a ferrite-martensite steel, the application of a tensile stress increases the Barkhausen activity of the martensite and ferrite phases, whereas a compressive one reduces it. In a second time, we induced residual stresses by applying a plastic deformation to ferrite-martensite steels. After a tensile plastic deformation, we observed that (i) compressive residual stresses appear in ferrite, and (ii) tensile residual stresses appear in martensite. An opposite behavior is observed after a compressive plastic deformation. These results show that the Barkhausen noise measurement makes it possible to highlight in a nondestructive way the distribution of the stresses in each of the two phases of a ferrite-martensite steel. This result could be used to characterize industrial Dual- Phases steels that are plastically deformed during mechanical processes.

An Analytical Solution for Three-Dimensional Elliptical Elastic-Plastic Rolling Contact

2014 ◽  
Vol 658 ◽  
pp. 207-212
Author(s):  
Gabriel Popescu
Keyword(s):  
Residual Stresses ◽  
Yield Criterion ◽  
Tangential Force ◽  
Rolling Direction ◽  
Three Dimensional ◽  
Rolling Contact ◽  
Material Behavior ◽  
Hertzian Contact ◽  
Plastic Behavior ◽  
Elastic Plastic

An analytical three-dimensional elastic-plastic over-rolling solution is used to evaluate the plastic strains and residual stresses. Central to this plastic contact formulation is the incremental approach to deal with non-linear material behavior. The Prandtl-Reuss constitutive equations in conjunction with Huber-Mises-Hencky yield criterion and Ramberg-Osgood strain-hardening relationships are applied to describe the plastic behavior of common hardened bearing steel. The model was extended to include the tangential force in the rolling direction, assumed to be proportional to the hertzian contact pressure. Comparisons of three-dimensional pure rolling and rolling/sliding contact results were provided to elucidate the differences in residual stresses and residual profiles in case of kinematic and work-hardening materials.

A Semi-Analytical 3-D Solution for Bending Under Tension

2012 ◽  
Vol 586 ◽  
pp. 302-305
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Li Hui Lang
Keyword(s):  
Yield Criterion ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Equivalent Strain ◽  
Large Strains ◽  
Flow Rule ◽  
Viscoplastic Material ◽  
Equivalent Strain Rate ◽  
Bending Under Tension ◽  
Associated Flow Rule

The paper concerns with three-dimensional analysis of the process of bending under tension for incompressible, rigid viscoplastic material at large strains. The constitutive equations consist of the Mises-type yield criterion and its associated flow rule. No restriction is imposed on the dependence of the equivalent stress on the equivalent strain rate. The problem is reduced to evaluating ordinary integrals and solving transcendental equations.

Ideal Flow in Plasticity

2007 ◽  
Vol 60 (6) ◽  
pp. 316-335 ◽  
Author(s):  
Kwansoo Chung ◽  
Sergei Alexandrov
Keyword(s):  
Yield Criterion ◽  
Three Dimensional ◽  
Flow Theory ◽  
Design Guidelines ◽  
Optimum Process ◽  
Computational Aspect ◽  
Flow Rule ◽  
Ideal Flow ◽  
Ideal Plastic ◽  
The Ideal

Ideal plastic flows constitute a class of solutions in the classical theory of plasticity based on, especially for bulk forming cases, Tresca’s yield criterion without hardening and its associated flow rule. They are defined by the condition that all material elements follow the minimum plastic work path, a condition which is believed to be advantageous for forming processes. Thus, the ideal flow theory has been proposed as the basis of procedures for the direct preliminary design of forming processes, which mainly involve plastic deformation. The aim of the present review is to provide a summary of both the theory of ideal flows and its applications. The theory includes steady and nonsteady flows, which are divided into three sections, respectively: plane-strain flows, axisymmetric flows, and three-dimensional flows. The role of the method of characteristics, including the computational aspect, is emphasized. The theory of ideal membrane flows is also included but separately because of its advanced applications based on finite element numerical codes. For membrane flows, restrictions on the constitutive behavior of materials are significantly relaxed so that more sophisticated anisotropic constitutive laws with hardening are accounted for. In applications, the ideal plastic flow theory provides not only process design guidelines for current forming processes under realistic tool constraints, but also proposes new ultimate optimum process information for futuristic processes.

Asymptotic Crack-Tip Fields for Mixed Stationary Crack under Plane Stress Conditions in Pressure Sensitive and Elastic-Plastic Materials

2010 ◽  
Vol 146-147 ◽  
pp. 611-614
Author(s):  
Chen Hua Lu ◽  
Su Fang Xing ◽  
Wen Jia Wang ◽  
Jian Bing Sang ◽  
Bo Liu
Keyword(s):  
Plane Stress ◽  
Yield Criterion ◽  
Crack Tip ◽  
Flow Rule ◽  
Basic Solution ◽  
Crack Tip Field ◽  
Plane Stress Condition ◽  
Elastic Plastic ◽  
Pressure Sensitive ◽  
Elastic Plastic Materials

Based on the parabolic yield criterion reflected by pressure sensitive and the SD effect, the material constitutive equation is given by orthogonal flow rule. In the plane stress condition, a basic solution in elastic-plastic crack tip field is given. The different structures of solutions with different plastic mixity are analyzed. Different parameters in crack-tip stress field and the singularity in the strain field are discussed. These results provide a theoretical reference for engineering applications.

Effect of length in rotational autofrettage of long cylinders with free ends

2021 ◽  
pp. 095440622110342
Author(s):  
Rajkumar Shufen ◽  
Uday Shanker Dixit
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Axial Stress ◽  
Fem Analysis ◽  
Longitudinal Axis ◽  
Pressure Vessels ◽  
Stress Changes ◽  
Different Types ◽  
Compressive Residual Stresses ◽  
Spherical Pressure

Thick-walled cylindrical and spherical pressure vessels are often subjected to autofrettage, a process in which the vessel is loaded at the inner wall to cause a partial or complete plastic deformation emanating from the inner wall, followed by unloading. This introduces the beneficial compressive residual stresses in the vicinity of the inner wall. Depending on the type of the loading, there are five different types of autofrettage processes— hydraulic, swage, explosive, thermal and rotational. This article analyzes the rotational autofrettage, in which the cylinder to be autofrettaged is loaded by rotating it about its longitudinal axis. The centrifugal forces cause the required plastic deformation in the cylinder. Hence, when the cylinder is unloaded by bringing it to rest, compressive hoop residual stresses are introduced in the vicinity of its inner wall. When long cylinders are rotated about their axes, the distribution of axial stress changes with length of the cylinder and affects the generation of the residual stresses in the autofrettaged cylinder. This effect is investigated here by a finite element method (FEM) analysis of rotational autofrettage of cylinder made up of A723 gun steel. The FEM analysis using ABAQUS® package reveals the presence of tensile axial residual stresses in the vicinity of the inner wall of the cylinder, which increase with length. The tensile residual stresses can be mitigated by constraining the ends of the cylinder during the rotational autofrettage.

Analyzing of Stainless Elliptical Cup Drawing Process

2010 ◽  
Vol 443 ◽  
pp. 116-121
Author(s):  
You Min Huang ◽  
Yi Wei Tsai
Keyword(s):  
Yield Criterion ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Forming Limit ◽  
Flow Rule ◽  
Drawing Ratio ◽  
Drawing Process ◽  
Simple Tension ◽  
Cup Drawing

A methodology of formulating an incremental elasto-plastic three-dimensional finite element model, which is based on Prandtl-Reuss flow rule and von Mises’s yield criterion respectively, associated with an updated Lagrangian formulation, is developed to simulate elliptical cup drawing process. An extended algorithm is proposed to formulate the boundary conditions, such as the yield of element, maximum allowable strain increment, maximum allowable rotation increment, maximum allowable equivalent stress increment, and tolerance for nodes getting out of contact with tool. In order to verify the reliability and accuracy of the FEM code, the fractured thickness of a specimen in the simple tension test is adopted as the fracture criterion of forming limit in simulation. A set of tools was designed to perform the elliptical cup drawing experiment on the hydraulic forming machine. According to the simulation and experimental results, the limit drawing ratio (LDR) amounts to about 2.136 for penetration in the elliptical cup drawing process of this study. This paper also found a comparison of the LDR of different tool radii. According to the definition of LDR, when the die radius is increased from R3.0mm to R9.0mm, the LDR would increase from 2.11 to 2.157. When the punch radius is increased from r3.0mm to r9.0mm, the LDR would increase from 2.07 to 2.181. This paper has provided a better understanding of the elliptical cup drawing process for improving the manufacturing processes and the design of tools.

Buckling and Post-Buckling of Thin Elastoplastic Cylindrical Shells With Finite Rotations

2000 ◽  
Author(s):  
Philippe Le Grognec ◽  
Anh Le Van
Keyword(s):  
Yield Criterion ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Thin Shells ◽  
Elastoplastic Material ◽  
Plane Stress Condition ◽  
Buckling Mode ◽  
Non Linear ◽  
Post Buckling ◽  
Non Linear System

Abstract An elastoplastic thin shell model is presented in this work in order to compute the buckling and post-buckling behavior of cylindrical shell-type structures. Standard assumptions in the shell kinematics allow us to develop a large deformation and finite rotation model for thin shells from the three-dimensional continuum. An elastoplastic constitutive model for thin shells is derived from the three-dimensional framework, assuming the plane stress condition. The von Mises yield criterion is adopted including non-linear isotropic and linear kinematic hardening. The resulting non-linear system is solved by a Newton-Raphson solution procedure, including the consistent linearization of the shell kinematics and the elastoplastic material model. The high non-linearities due to the buckling-type instabilities, especially those occuring in the neighbourhood of critical points, necessitate the use of an appropriate step-length control. An arc-length method has been successfully implemented for passing through limit points (load or displacement peaks) where pure load or displacement controls fail. The proposed method is effective in handling both sharp snap-throughs and snap-backs. Two numerical examples are presented in view of the assessment of the proposed approach and a particular attention is devoted to the post-buckling of hollow cylinders under axial compression. We identify several types of buckling mode for these structures, among which the axisymmetric mode, the “diamond” mode and the “elephant foot” mode, depending on geometry and boundary conditions.

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