Effects of Strain Hardening and Initial Yield Strength on Machining-Induced Residual Stresses

2007 ◽  
Vol 129 (4) ◽  
pp. 567-579 ◽  
Author(s):  
Mohamed N.A. Nasr ◽  
E.-G. Ng ◽  
M. A. Elbestawi
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Plastic Behavior ◽  
Workpiece Material ◽  
Initial Yield ◽  
Wide Range ◽  
Steel Aisi ◽  
Aisi H13 Tool Steel

Finite element analysis was used in the current study to examine the effects of strain hardening and initial yield strength of workpiece material on machining-induced residual stresses (RS). An arbitrary–Lagrangian–Eulerian finite element model was built to simulate orthogonal dry cutting with continuous chip formation, then a pure Lagrangian analysis was used to predict the induced RS. The current work was validated by comparing the predicted RS profiles in four workpiece materials to their corresponding experimental profiles obtained under similar cutting conditions. These materials were AISI H13 tool steel, AISI 316L stainless steel, AISI 52100 hardened steel, and AISI 4340 steel. The Johnson–Cook (J–C) constitutive equation was used to model the plastic behavior of the workpiece material. Different values were assigned to the J-C parameters representing the studied properties. Three values were assigned to each of the initial yield strength (A) and strain hardening coefficient (B), and two values were assigned to the strain hardening exponent (n). Therefore, the full test matrix had 18 different materials, covering a wide range of commercial steels. The yield strength and strain hardening properties had opposite effects on RS, where higher A and lower B or n decreased the tendency for surface tensile RS. Because of the opposite effects of A and (B and n), maximum surface tensile RS was induced in the material with minimum A and maximum B and n values. A physical explanation was provided for the effects of A, B, and n on cutting temperatures, strains, and stresses, which was subsequently used to explain their effects on RS. Finally, the current results were used to predict the type of surface RS in different workpiece materials based on their A, B, and n values.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Effect of Steel Properties on Buckling Pressure of Corroded Pipelines

2017 ◽  
Vol 898 ◽  
pp. 741-748 ◽  
Author(s):  
Meng Li ◽  
Hong Zhang ◽  
Meng Ying Xia ◽  
Kai Wu ◽  
Jing Tian Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Strain Hardening ◽  
Corrosion Damage ◽  
Element Model ◽  
External Pressure ◽  
Strain Hardening Exponent ◽  
The Finite Element Method ◽  
Collapse Pressure ◽  
Steel Properties

Due to the harsh environment for submarine pipelines, corrosion damage of the pipeline steels is inevitable. After the corrosion damage, pipelines are prone to failure and may cause serious consequences. The analysis of the effects of different steel properties on the collapse pressure of pipelines with corrosion defects is of importance for the option of appropriate pipeline and avoiding accidents. Based on the finite element method, the finite element model of the pipeline with defects under external pressure was built. Firstly, the accuracy of the numerical model was validated by comparing with previous experimental results. The effects of yield strength and strain hardening exponent on collapse pressure of pipelines with different sizes of defect were discussed in detail. Results showed that the yield strength and strain hardening exponent have different influences on collapse pressure: the collapse pressure increases with the increasing yield strength, and the collapse pressure decreases with the increasing strain hardening exponent.

Analytical evaluation of thermally induced residual stresses in ground components

2003 ◽  
Vol 217 (5) ◽  
pp. 471-482 ◽  
Author(s):  
D G Walsh ◽  
A A Torrance ◽  
J Tiberg
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Critical Temperature ◽  
Yield Strength ◽  
Residual Stresses ◽  
Material Properties ◽  
Analytical Evaluation ◽  
Simple Method ◽  
Thermally Induced

Although thermally induced tensile residual stresses have been known to occur in ground components, it has not been possible to predict the critical temperature at which these stresses begin to manifest themselves in the workpiece. In this paper, a model of the formation of thermally induced tensile residual stresses is proposed and a simple method of calculating the critical temperature above which tensile residual stresses occur is developed. The analysis makes use of dimensional methods to characterize the critical temperature. In addition, a formula characterizing the yield strength as a function of temperature was developed. The model was then validated using finite element techniques and some experimental data. The analysis reveals that it is possible to determine the critical temperature above which tensile residual stresses will be manifested based on readily available material properties. A case study illustrates the application of the technique.

Increasing Yield Strength of AISI 316L Plastically Deformed by Expanded Hole Techniques

2017 ◽  
Vol 901 ◽  
pp. 97-102
Author(s):  
Urip Agus Salim ◽  
Suyitno ◽  
Rahadyan Magetsari ◽  
Muslim Mahardika
Keyword(s):  
Numerical Simulation ◽  
Yield Strength ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Cold Working ◽  
Small Crack ◽  
Aisi 316L ◽  
Hardening Mechanism ◽  
Working Method ◽  
Fatigue Mechanism

AISI 316L has been used to produce implant plates such as dynamic copmresion plates (DCP). The implant plates might experienced failure due to either suffer higher stresses exceeding the allowable maximum strenght or presents small crack growing through fatigue mechanism. Most of DCP fractures occured at the gliding holes region. This study conducted improving strength of DCP locally on the gliding holes. Strengthening on the gliding holes of DCP was performed by cold working method involving plastically deformation using an expanded hole technique. This study was conducted by both experimental and numerical simulation. Increasing strength locally on the gliding hole region was evaluated by measuring some parameters incorporated with strain hardening mechanism such as hardness and residual stresses. Increasing yields strength locally on the hole region was estimated by Takakuwa’s formulas. By this method, yields strength of the gliding hole of DCP made of AISI 316L increased from 325 MPa to be 600−1050 MPa.

A Finite Element Study of Elasto-Plastic Hemispherical Contact

2003 ◽  
Author(s):  
Robert L. Jackson ◽  
Itzhak Green
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Constant Factor ◽  
Elastic Model ◽  
Asperity Contact ◽  
Finite Element Study ◽  
Perfectly Plastic ◽  
Wide Range ◽  
Elastic Perfectly Plastic ◽  
Element Study

This work presents a finite element study of elasto-plastic hemispherical contact. The results are normalized such that they are valid for macro contacts (e.g., rolling element bearings) and micro contacts (e.g., asperity contact). The material is modeled as elastic-perfectly plastic. The numerical results are compared to other existing models of spherical contact, including the fully plastic case (known as the Abbott and Firestone model) and the perfectly elastic case (known as the Hertz contact). At the same interference, the area of contact is shown to be larger for the elasto-plastic model than that of the elastic model. It is also shown, that at the same interference, the load carrying capacity of the elasto-plastic modeled sphere is less than that for the Hertzian solution. This work finds that the fully plastic average contact pressure, or hardness, commonly approximated to be a constant factor (about three) times the yield strength, actually varies with the deformed contact geometry, which in turn is dependant upon the material properties (e.g., yield strength). The results are fit by empirical formulations for a wide range of interferences and materials for use in other applications.

Analytical and Numerical Modelling of Sheet Plate Cold Expanded Hole Subjected to Reverse Yielding

2019 ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Hacène Touahri
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Analytical Model ◽  
Life Assessment ◽  
Thick Wall ◽  
Plastic Behavior ◽  
Alloy Plate ◽  
Proposed Model ◽  
Reverse Yielding

Abstract Predicting and mitigating the effect of expansion induced by cold working on damage fatigue accumulation and life assessment of aluminum alloy is a common process in the aeronautics industry, especially to extend the fatigue lifetime of their structures. This process aims at generating residual stresses and increases thereby the strength of hollow parts including aluminum alloy plate holes that are employed in manufacturing the airplane fuselage. An analytical model to predict the residual stresses induced during the expansion process due to the cold strain hardening is developed. The proposed model is based on an elasto-plastic behavior, with a power law material behaviour and relies on the theory of autofrettaged thick wall cylinders in plane strain state to which reverse yielding is incorporated. The application of Hencky theory of plastic deformation is used in the analytical calculations of the stresses and strains. Finite-element numerical simulation is used to validate the developed analytical model by comparison of the radial, Hoop, longitudinal and equivalent stresses for both the loading and unloading phases. The obtained results show clearly that the level of residual stresses depends mainly on the interference and strain hardening while reverse yielding reduce the stresses near the hole.

The Effects of Operational, Testing and Material Characterisations On the Change in Yield Strength From Plate to Pipe

2021 ◽  
Author(s):  
Jingsi Jiao ◽  
Cheng Lu ◽  
Valerie Linton ◽  
Frank Barbaro
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Yield Strength ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Element Model ◽  
Critical Knowledge ◽  
Operational Testing ◽  
Wide Range ◽  
The Individual

Abstract The mechanical performance of the pipe sample has a direct influence on their application in real environments and a significant economic impact on manufacturers, especially when the pipe products do not meet required specifications. There is often a change in the yield strength from plate to pipe due to strain hardening and the Bauschinger effect. The current work sets out to provide a critical knowledge base for this change, with emphasizing the important influence of the plate mechanical properties on the pipe. So that the quality of pipe can be further ensured. In the work, firstly, the historical data of the pipe yield strength were collected and plotted together from a wide range of published sources to provide a broad quantitative insight, which provides a quantitative review on the parameters that govern the final pipe yield strength. Secondly, a Finite Element model of the pipe forming and mechanical evaluation was developed and then validated with available industrial testing results, in where the effects of operational and testing parameters on the pipe yield strength were analysed and discussed in detail. Finally, using the validated Finite Element model, a parametric study was conducted to dissect the individual role that each of the material parameters plays on changing the yield strength from plate to pipe. We found that the yield strength of the pipe can differ significantly. This work sheds lights on the desired plate mechanical properties to optimize the final pipe yield strength.

Finite element parametric study of the split sleeve cold expansion on residual stresses and pulling force

2021 ◽  
pp. 095440622110255
Author(s):  
Mithun K Dey ◽  
Dave Kim ◽  
Hua Tan
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Residual Stresses ◽  
Parametric Study ◽  
Industrial Applications ◽  
Published Data ◽  
Fe Model ◽  
Residual Stress Field ◽  
Cold Expansion ◽  
Pulling Force

Split sleeve cold expansion (SSCE) is a crucial cost-effective process to improve the fatigue life of metallic structures with holes in the aerospace industry. In this study, the effects of the workpiece material’s yield strength (290.9 MPa to 377.8 MPa) and the applied SSCE expansion percentage (3.330% to 4.377%) on mandrel pulling force and residual stresses were investigated numerically for aluminum 2024-T351. A three-dimensional finite element (FE) model was developed to simulate the SSCE process using a commercial FE software, ABAQUS. The model geometries, material non-linearities, and contact conditions were adopted according to aerospace industrial applications’ standards. After the numerical model was validated with the published data, a parametric study with variable material properties and expansion percentage was conducted using the FE model. Our parametric study shows that an increase in both the Al workpiece’s yield strength and SSCE expansion percentage can improve the induced residual stresses in the hoop direction around the cold expanded hole; however, the workpiece’s yield strength has a higher impact on the residual stress field. The in-process pulling force during the SSCE process increases with increasing workpiece yield strength and expansion percentage.

A 3D Finite Element Study on the Friction Effects on Material Flow Under the Cutting Edge in Superfinish Hard Milling H13 Tool Steel

2010 ◽  
Author(s):  
H. M. Singh ◽  
Y. B. Guo
Keyword(s):  
Finite Element ◽  
Tool Steel ◽  
Material Flow ◽  
Chip Thickness ◽  
Milling Process ◽  
Cutting Edge ◽  
Plastic Behavior ◽  
3D Finite Element ◽  
H13 Tool Steel ◽  
Aisi H13 Tool Steel

Milling hardened steels has emerged as a key technology in mold and die manufacturing industries. In cutting, a portion of work material is pushed upward by the tool rake face to form the chip while the other portion below this layer is ploughed under the cutting edge to become the machined surface. Although the ploughed material is a very small fraction of the uncut chip thickness, it determines surface integrity after machining. In this study, a 3D finite element simulation model of milling hardened AISI H13 tool steel (HRC 50) has been developed to study material deformation under the cutting edge of a milling insert. The ploughed depth in the range of 0.6 μm to 3.0 μm is used to study the material flow under the cutting edge. Friction between the cutting edge and workpiece surface has a significant influence on the ploughed depth. Different coefficients of friction are used to study their effects on stresses/strains and temperature during ploughing. The Johnson-Cook model is used to model the plastic behavior of workpiece material. The 3D finite element analysis gives an insight into some key issues in a milling process. The FEA model illustrates the effects of micro cutting edge geometry on pile-up in front of the cutting edge, transient stresses and temperatures, and a transition from ploughing to cutting in a milling process.

scholarly journals Residual Stress From Cold Expansion of Fastener Holes: Measurement, Eigenstrain, and Process Finite Element Modeling

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Renan L. Ribeiro ◽  
Michael R. Hill
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Slow Crack Growth ◽  
Measurement Data ◽  
Equivalent Plastic Strain ◽  
Contour Method ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Cold Expansion

Cold expansion (CX) is a material processing technique that has been widely used in the aircraft industry to enhance fatigue life of structural components containing holes. CX introduces compressive hoop residual stresses that slow crack growth near the hole edge. The objective of this paper is to predict residual stresses arising from cold expansion using two different finite element (FE) approaches, and compare the results to measurement data obtained by the contour method. The paper considers single-hole, double-hole, and triple-hole configurations with three different edge margins. The first FE approach considers process modeling, and includes elastic–plastic behavior, while the second approach is based on the eigenstrain method, and includes only elastic behavior. The results obtained from the FE models are in good agreement with one another, and with measurement data, especially close to the holes, and with respect to the effect of edge margin on the residual stress distributions. The distribution of the residual stress and equivalent plastic strain around the holes is also explored, and the results are discussed in detail. The eigenstrain method was found to be very useful, providing generally accurate predictions of residual stress.

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