scholarly journals Effects of Residual Stresses on the Fatigue Lifetimes of Self-Piercing Riveted Joints of AZ31 Mg Alloy and Al5052 Al Alloy Sheets

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2037
Author(s):  
Young-In Lee ◽  
Ho-Kyung Kim
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Equivalent Stress ◽  
Maximum Error ◽  
Az31 Alloy ◽  
Al Alloy ◽  
Element Analysis ◽  
Riveted Joints ◽  
Magnesium Az31

During the self-piercing riveting (SPR) process, residual stress develops due to the high plastic deformation of the sheet materials. In this study, the effect of the residual stress on the fatigue lifetime of SPR joints with dissimilar magnesium AZ31 alloy and aluminum Al5052 alloy sheets was evaluated. The residual stress distribution was derived through a simulation of the SPR process by the FEA (finite element analysis). The measured values by the X-ray diffraction technique confirmed that the validity of the simulation has a maximum error of 17.2% with the experimental results. The fatigue strength of the SPR joint was evaluated at various loading angles using tensile-shear and cross-shaped specimens. It was found that the compressive residual stresses of the joint reduce the stress amplitude by 13% at 106 cycles lifetime, resulting in extension of its lifetime to approximately 3.4 million cycles from 106 cycles lifetime. Finally, it was confirmed that the fatigue life of SPR joints was appropriately predicted within a factor of three using the relationship between the fatigue life and the equivalent stress intensity factor. The fatigue resistance of the magnesium AZ31 alloy on the upper sheet was found to govern fatigue lifetimes of SPR joints of dissimilar magnesium AZ31 alloy sheets.

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.

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.

Investigational Advances in Residual Stresses by Hard Turning

2004 ◽  
Vol 471-472 ◽  
pp. 523-527 ◽  
Author(s):  
Xue Ping Zhang ◽  
C.Richard Liu ◽  
Zheng Qiang Yao
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Hard Turning ◽  
Dominant Role ◽  
Published Data ◽  
Element Analysis ◽  
Average Value ◽  
Experimental Approaches ◽  
And Performance

Hard turning has been recognized as a substitute for abrasive-based processes not only due to its flexibility, economic benefit and environmental consciousness, but also its determinate surface integrity (surface roughness, micro hardness and residual stress), which is superior and more consistent than ground surfaces. Residual stress is of considerable industrial importance because they can affect failure by fatigue, creep or cracking. It is believed that compressive residual stresses are more favorable for fatigue life than tensile residual stresses. Hard turning generally generates compressive residual stress, which is the dominant role in determining both the variance and average value of fatigue life. This paper focus on the published data, especially C.R.Liu’s research, which address the residual stresses by hard turning in terms of experimental approaches， theoretical modeling，numerical simulation by Finite Element Analysis (FEA) and the correlation with its fatigue life and performance. The potential trends and key technologies for residual stresses are predicated and discussed so as to capture the most effective approach to investigate residual stress by hard turning.

Finite Element Analysis of the Valve Spring with Different Engine Speed

2011 ◽  
Vol 382 ◽  
pp. 224-228 ◽  
Author(s):  
Hong Yan Li ◽  
Xian Yue Gang ◽  
Shan Chai
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Engine Speed ◽  
Equivalent Stress ◽  
Spring Back ◽  
Element Analysis ◽  
Valve Spring ◽  
Intake Process

The valve spring endures alternate load during work, whose dynamic response is vital to the whole performance of the engine valve system. Finite element analysis of the valve spring is researched in the intake process of an engine during which the engine speed varies from 1000r/min to 5000r/min. The investigation indicates that the equivalent stress achieves maximum when the valve is full open following with spring back to some extent, although some residual stress still exist until the valve closed fully, both the intensity and fatigue life can satisfy design need. The distribution over all intake process appears normal distribution at low speed, the stress oscillates seriously with speed increasing.

On Modeling the Rolling Contact Fatigue Performance Based on Residual Stresses Generated by Superfinish Hard Turning

2000 ◽  
Author(s):  
Salah R. Agha ◽  
C. Richard Liu
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Hard Turning ◽  
Rolling Contact Fatigue ◽  
Equivalent Stress ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Contact Fatigue Life ◽  
The Difference

Abstract It was shown earlier [Agha and Liu, 1998, 1999, 2000] that different cutting conditions, within superfinish hard turning, would lead to significantly different rolling contact fatigue lives. In this study, residual stresses were measured. The rolling contact fatigue life was then modeled using a maximum modified equivalent stress that takes residual stresses into account. It is seen that the maximum modified equivalent stress is a better predictor than the maximum Hertzian stress, but, still not accurate, given the consistent repeatability of the tested workpieces [Agha and Liu, 2000]. The difference in the nature of residual stresses produced by grinding and hard turning is used to show why the inclusion of the maximum modified equivalent stress, its location and the volume at risk, improves the power of the model to predict the rolling contact fatigue lives of the hard turned surfaces. This model is the best up to date for predicting the fatigue life of a surface, especially when residual stress is a factor.

Finite Element Analysis of the Rolling Contact Fatigue Life of Railcar Wheels

2008 ◽  
Vol 575-578 ◽  
pp. 1461-1466
Author(s):  
Byeong Choon Goo ◽  
Jung Won Seo
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Element Analysis ◽  
Railway Vehicles ◽  
Contact Fatigue Life

Railcar wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles have been more severe in recent years due to speed-up. Therefore, a more precise evaluation of railcar wheel life and safety has been requested. Wheel/rail contact fatigue and thermal cracks due to braking are two major mechanisms of the railcar wheel failure. One of the main sources influencing on the contact zone failure is residual stress. The residual stress in wheels formed during heat treatment in manufacturing changes in the process of braking. Thus the fatigue life of railcar wheels should be estimated by considering both thermal stress and rolling contact. Also, the effect of residual stress variation due to manufacturing process and braking process should be included in simulating contact fatigue behavior. In this paper, an evaluation procedure for the contact fatigue life of railcar wheels considering the effects of residual stresses due to heat treatment, braking and repeated contact load is proposed. And the cyclic stressstrain history for fatigue analysis is simulated by finite element analysis for the moving contact load.

Effect of Thermal Residual Stresses on Polymer/Metal Interfacial Adhesion

1999 ◽  
Author(s):  
Qizhou Yao ◽  
Jianmin Qu
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Interfacial Crack ◽  
Thermal Residual Stress ◽  
Element Analysis ◽  
Thermal Residual Stresses ◽  
Interfacial Cracks ◽  
Cte Mismatch ◽  
Elastic Mismatch

Abstract In this study, the apparent fracture toughness of the interfaces of several epoxy-based polymeric adhesives and metal (aluminum) substrate is experimentally measured. Double layer specimens with initial interfacial cracks are made for four-point bending tests. Thermal residual stresses exist on the interface due to the coefficient of thermal expansion (CTE) mismatch between the underfill and aluminum. Silica fillers are used to modify the CTE of the epoxy-based adhesives so that various levels of interface thermal residual stresses are achieved. Finite element analysis is also performed to quantify the effects of CTE mismatch as well as the elastic mismatch across the interface. It is found that the apparent interfacial toughness is significantly affected by the thermal residual stress, while the effect of elastic mismatch is negligible. In general thermal residual stress undermines the resistance to an interfacial crack. In some cases the residual stress is sufficient to result in adhesive and/or cohesive failure.

Influence of Different Surface Treatments on Fatigue Life of 7050 Al Alloy

2019 ◽  
Vol 944 ◽  
pp. 142-148 ◽  
Author(s):  
Nan Li ◽  
Hai Tao Li ◽  
Jing Yi Zhou ◽  
Hong Tao Liu ◽  
Chang Kui Liu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Surface Analysis ◽  
Shot Peening ◽  
Surface Treatments ◽  
Al Alloy ◽  
Stress Measurements ◽  
Fracture Surface Analysis

The fatigue life of 7050 Al alloy samples after different surface treatments, i.e., as-machined, anodizing, shot peening, and shot peening followed by anodizing, had been tested. The shot peening treatment specimens presented the longest average fatigue life. The fatigue life of anodizing treatment specimens decreased by 69.3% and 78.8% at 215 MPa and 260 MPa stress levels than as-machined ones. Introducing the shot peening treatment before anodizing can increase the fatigue life by 220% / 296.9% at 215 MPa/260 Mpa than that only treated by anodizing. The effect of the surface treatments on the fatigue life were studied by performing surface morphology investigation, residual stress measurements and fracture surface analysis.

Numerical Simulation of Residual Stresses due to Multipass Welding in High Strength Steel Plates and Validation against Experimental Measurements

2018 ◽  
Vol 941 ◽  
pp. 269-273
Author(s):  
Constant Ramard ◽  
Denis Carron ◽  
Philippe Pilvin ◽  
Florent Bridier
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
High Strength Steel ◽  
High Strength ◽  
Steel Plates ◽  
Contour Method ◽  
Hole Drilling ◽  
Experimental Measurements ◽  
Element Analysis ◽  
Multipass Welding

Multipass arc welding is commonly used for thick plates assemblies in shipbuilding. Sever thermal cycles induced by the process generate inhomogeneous plastic deformation and residual stresses. Metallurgical transformations contribute at each pass to the residual stress evolution. Since residual stresses can be detrimental to the performance of the welded product, their estimation is essential and numerical modelling is useful to predict them. Finite element analysis of multipass welding of a high strength steel is achieved with a special emphasis on mechanical and metallurgical effects on residual stress. A welding mock-up was specially designed for experimental measurements of in-depth residual stresses using contour method and deep hole drilling and to provide a simplified case for simulation. The computed results are discussed through a comparison with experimental measurements.

Finite Element Analysis Model of Corrosion Fatigue for TIG Welding Workpiece

2016 ◽  
Vol 707 ◽  
pp. 154-158
Author(s):  
Somsak Limwongsakorn ◽  
Wasawat Nakkiew ◽  
Adirek Baisukhan
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Corrosion Fatigue ◽  
Welding Process ◽  
Simulation Software ◽  
Tig Welding ◽  
Element Analysis ◽  
Fea Model

The proposed finite element analysis (FEA) model was constructed using FEA simulation software, ANSYS program, for determining effects of corrosion fatigue (CF) from TIG welding process on AISI 304 stainless steel workpiece. The FEA model of TIG welding process was developed from Goldak's double ellipsoid moving heat source. In this paper, the residual stress results obtained from the FEA model were consistent with results from the X-ray diffraction (XRD) method. The residual stress was further used as an input in the next step of corrosion fatigue analysis. The predictive CF life result obtained from the FEA CF model were consistent with the value obtained from stress-life curve (S-N curve) from the reference literaturature. Therefore, the proposed FEA of CF model was then used for predicting the corrosion fatigue life on TIG welding workpiece, the results from the model showed the corrosion fatigue life of 1,794 cycles with testing condition of the frequency ( f ) = 0.1 Hz and the equivalent load of 67.5 kN (equal to 150 MPa) with R = 0.25.

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