Finite Element Based Evaluation of Abrasive Waterjet Peening With Elastic Prestress: Effect of Prestress Loading

2012 ◽  
Author(s):  
Balaji Sadasivam ◽  
Dwayne Arola
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Treatment Process ◽  
High Cycle Fatigue ◽  
Potential Surface ◽  
Axial Loading ◽  
Fatigue Loading ◽  
Stress Fields ◽  
Abrasive Waterjet ◽  
Residual Stress Field

Abrasive Waterjet (AWJ) peening has emerged as a potential surface treatment process for components subjected to high–cycle fatigue loading and that require a “rough” surface. Conducting treatments while subjecting the surface to tensile elastic prestress has resulted in an increase in the magnitude and depth of residual stress. Recent finite element based studies have revealed that the residual stress field in AWJ peening is influenced by the boundary conditions and whether the prestress is administered by load or displacement control. However, previous investigations concerned with AWJ peening have been limited to a flexural loading arrangement to achieve tensile prestress of the treated surface. In the present investigation, a finite element based study is conducted to evaluate the effect of prestress loading configurations and a comparison of flexural vs axial loading on the residual stress fields resulting from peening surface treatments. Results show that the prestress loading influences the depth of residual stress and axial prestress results in a greater depth than that achieved with flexure prestress.

Thermal Simulation of an Arbitrary Residual Stress Field in a Fully or Partially Autofrettaged Thick-Walled Spherical Pressure Vessel

2008 ◽  
Author(s):  
M. Perl
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Field ◽  
Pressure Vessel ◽  
Stress Fields ◽  
Equivalent Temperature ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Spherical Pressure ◽  
The Ideal

The equivalent thermal load was previously shown to be the only feasible method by which the residual stresses due to autofrettage and its redistribution, as a result of cracking, can be implemented in a finite element analysis, of a fully or partially autofrettaged thick-walled cylindrical pressure vessel. The present analysis involves developing a similar methodology for treating an autofrettaged thick-walled spherical pressure vessel. A general procedure for evaluating the equivalent temperature loading for simulating an arbitrary, analytical or numerical, spherosymmetric autofrettage residual stress field in a spherical pressure vessel is developed. Once presented, the algorithm is applied to two distinct cases. In the first case, an analytical expression for the equivalent thermal loading is obtained for the ideal autofrettage stress field in a spherical shell. In the second case, the algorithm is applied to the discrete numerical values of a realistic autofrettage residual stress field incorporating the Bauschinger effect. As a result, a discrete equivalent temperature field is obtained. Furthermore, a finite element analysis is performed for each of the above cases, applying the respective temperature field to the spherical vessel. The induced stress fields are evaluated for each case and then compared to the original stress. The finite element results prove that the proposed procedure yields equivalent temperature fields that in turn simulate very accurately the residual stress fields for both the ideal and the realistic autofrettage cases.

scholarly journals Process Induced Residual Stress Effect on Fatigue Lifetime of Automotive Steel Components

2014 ◽  
Vol 996 ◽  
pp. 808-813
Author(s):  
Elias Merhy ◽  
Ngadia Taha Niane ◽  
Bastien Weber ◽  
Philippe Bristiel
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Welding Process ◽  
Fatigue Loading ◽  
Stress Effect ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Fatigue Lifetime

Metal Active Gas (MAG) welding process of steel sheets generates, in the vicinity of the welding joint, the well-known Heat Affected Zone (HAZ) in which the material presents more microstructural defects compared to the original metal. Since high cycle fatigue is largely dependent on the material microstructure features, the HAZ is considered as the weakest zone under high cycle fatigue loading. In addition, the welding causes, in the Heat Affected Zone, irreversible plastic strains that induce important residual stress fields in this critical zone of the structure. Therefore, in order to properly predict the high cycle fatigue life time of the welded automotive components, it is of primordial importance to first identify and then consider, if necessary, the welding induced residual stress field in the structure modeling. In this work, it is found that residual stresses have non-negligible impact on high cycle fatigue lifetime, while its effect is minor in the low cycle fatigue domain.

Predictions of Residual Stresses in the Mechanical Roll Expansion of HX Tubes Into TEMA Grooves

2003 ◽  
Author(s):  
Dennis K. Williams
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Tube Wall ◽  
Initial Study ◽  
Stress Fields ◽  
The Finite Element Method ◽  
Residual Stress Field ◽  
Steel Tubes

The mechanical roll expansion of heat exchanger tubes into tubesheets containing TEMA grooves, which are thought to aid in the mechanical integrity of the tube-to-tubesheet (TTT)joint, has for many years provided an acceptable means of completing a TTT joint. Inherent with the intentional roll expansion of the tube is the creation of a tensile residual stress field within the tube that is greatest in the transition region between the expanded and unexpanded zones of the tube. An additional complicating factor in the tube-to-tubesheet joint design is the choice of utilizing a seal weld or a “full strength” weld at the tube end in conjunction with a level of roll expansion quantified by the degree of tube wall reduction. This paper presents the results of an initial study of the mechanical roll expansion of 1 inch diameter tubes into a typical TEMA-R designed tubesheet, utilizing two grooves in the tubesheet hole. Two combinations of tube and tubesheet materials are studied that include duplex stainless steel tubes and tubesheet, while the second combination includes type 321 tubes roll expanded into a 2-1/4 Cr-1 Mo tubesheet, clad with 321 SS overlay. The predicted residual stress fields are calculated by the finite element method and employ a simplified two dimension nonlinear axisymmetric model.

An Evaluation of Abrasive Waterjet Peening With Elastic Prestress

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
B. Sadasivam ◽  
A. Hizal ◽  
S. Park ◽  
D. Arola
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Surface Texture ◽  
Surface Stress ◽  
Treatment Process ◽  
Abrasive Waterjet ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Stress Zone ◽  
Study Application

Abrasive waterjet peening (AWJP) has been conceived as a new surface treatment process capable of achieving desired changes in surface texture, chemistry, and residual stress simultaneously. In the present investigation, the influence of elastic prestress on the residual stress resulting from AWJP was studied. Treatments were conducted on steel, as well as nickel and titanium alloy targets subjected to an elastic prestress ranging from 0% to 75% of the material’s yield strength. The results showed that a tensile elastic prestress increases the surface residual stress and the depth of the compressive stress zone. The surface residual stress in each metal increased nonuniformly with magnitude of prestress; the maximum surface residual stress was obtained at an applied prestress between 45% and 60% of the substrate yield strength. Overall, the increases in surface stress and depth that were obtained reached 100% and 50%, respectively. There were no changes to the surface texture caused by the prestress. According to results of this study, application of an elastic prestress can serve as an effective method for improving characteristics of the residual stress field in components treated using AWJP.

Finite element analysis of residual stress evolution with multiple impacts on one point in ultrasonic impact treatment process

2016 ◽  
Vol 232 (7) ◽  
pp. 1201-1211 ◽  
Author(s):  
Shengsun Hu ◽  
Chaobo Guo ◽  
Dongpo Wang ◽  
Zhijiang Wang ◽  
Chao Huang
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Treatment Process ◽  
Equivalent Plastic Strain ◽  
Multiple Impacts ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Element Analysis ◽  
Ultrasonic Impact Treatment

The ultrasonic impact treatment process is widely used to improve the fatigue life of the weldments by inducing compressive residual stresses at the sub-surface. The purpose of the article is to conduct the dynamic elastic–plastic finite element analysis of multiple impacts on 5A06 aluminum alloy with different controlled parameters. The numerical model was validated by pin drop test. The changes in penetration depth, maximum compressive residual stress, and surface residual stress were obtained by analyzing the residual stress field and equivalent plastic strain. The effect of impact times, impact velocities, pin shapes, and impact angles on the residual stress was investigated so that the ultrasonic impact treatment parameters could be controlled to obtain expected residual stress distributions.

A Fundamental Study of the Interaction of Residual Stress and Applied Loading on Fracture

2010 ◽  
Author(s):  
C. J. Aird ◽  
M. J. Pavier ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Field ◽  
Crack Closure ◽  
Applied Load ◽  
Element Model ◽  
Residual Stress Field ◽  
Fundamental Study ◽  
Analytical Expression ◽  
Applied Loading

This paper presents the results of a fundamental finite-element based study of the crack-closure effects associated with combined residual and applied loading. First, an analytical expression for a representative two-dimensional residual stress field is derived. This residual stress field contains a central compressive region surrounded by an equilibrating tensile region. The analytical expression allows the size and shape of the field to be varied along with the magnitude of the residual stress. The residual stress field is then used as a prescribed initial stress field in a finite element model, in addition to a far field applied load. By introducing cracks of increasing length into these models, charts of stress-intensity-factor versus crack length are produced for different relative magnitudes of residual stress and applied load and for different sizes and shape of the residual stress field. These charts provide insight into the way in which crack-tip conditions evolve with crack growth under conditions of combined residual and applied loading and also enable conditions of crack closure and partial closure to be identified.

Design Optimisation of a Ferritic Ring Weld Specimen Using FE Modelling

2009 ◽  
Author(s):  
Christopher M. Gill ◽  
Paul Hurrell ◽  
John Francis ◽  
Mark Turski
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Finite Element Modelling ◽  
Post Weld Heat Treatment ◽  
Stress Fields ◽  
Element Modelling ◽  
Weld Heat

This paper describes the design optimisation of an SA508 ferritic steel ring weld specimen using FE modelling techniques. The aim was to experimentally and analytically study the effect of post weld heat treatment upon a triaxial residual stress field. Welding highly constrained geometries, such as those found in some pressure vessel joints, can lead to the formation of highly triaxial stress fields. It is thought that application of post weld heat treatments will not fully relax hydrostatic stress fields. Therefore a ferritic multi-pass ring weld specimen was designed and optimised, using 2D finite element modelling, to generate a high magnitude triaxial stress field. The specimen thickness and weld-prep geometry was optimised to produce a large hydrostatic stress field and still allow efficient use of neutron diffraction to measure the residual stress. This paper reports the development of the test specimen geometry and compares the results of welding FE analysis and neutron diffraction measurements. Welding residual stresses were experimentally determined using neutron diffraction; both before post weld heat treatment. Three dimensional moving heat source weld finite element modelling has been used to predict the residual stresses generated by the welding process used. Finite element modelling examined the effect of phase transformation upon the residual stress field produced by welding. The relaxation of welding stresses by creep during post weld heat treatment has also been modelled. Comparisons between the modelled and measured as-welded residual stress profiles are presented. This work allows discussion of the effect of post weld heat treatment of triaxial stress fields and determines if finite element modelling is capable of correctly predicting the stress relaxation.

Temperature and Residual Stress Fields in an Austenitic Circumferential Pipe Weld

2002 ◽  
Author(s):  
Ruthard Bonn ◽  
Klaus Metzner ◽  
H. Kockelmann ◽  
E. Roos ◽  
L. Stumpfrock
Keyword(s):  
Residual Stress ◽  
Numerical Calculation ◽  
Stress Field ◽  
Quantitative Determination ◽  
Welding Residual Stress ◽  
Stress Fields ◽  
Residual Stress Field ◽  
Circumferential Welds ◽  
The Impact

The main target of a research programme “experimental and numerical analyses on the residual stress field in the area of circumferential welds in austenitic pipe welds”, sponsored by Technische Vereinigung der Großkraftwerksbetreiber e. V. (VGB) and carried out at MPA Stuttgart, was the validation of the numerical calculation for the quantitative determination of residual stress fields in austenitic circumferential pipe welds. In addition, the influence of operational stresses as well as the impact of the pressure test on the residual stress state had to be examined. By using the TIG orbital welding technique, circumferential welds (Material X 10 CrNiNb 18 9 (1.4550, corresponding to TP 347) were produced (geometric dimensions 255.4 mm I.D. × 8.8 mm wall) with welding boundary conditions and weld parameters (number of weld layers and weld built-up, seam volume, heat input) which are representative for pipings in power plants. Deformation and temperature measurements accompanying the welding, as well as the experimentally determined (X-ray diffraction) welding residual stress distribution, served as the basis for the verification of numeric temperature and residual stress field calculations. The material model on which the calculations were founded was developed by experimental weld simulations in the thermo-mechanical test rig GLEEBLE 2000 for the determination of the material behaviour at different temperatures and elasto-plastic deformation. The numeric calculations were carried out with the Finite Element program ABAQUS. The comparison of the calculation results with the experimental findings confirms the proven validation of the developed numerical calculation models for the quantitative determination of residual stresses in austenitic circumferential pipings. The investigation gives a well-founded insight into the complex thermo-mechanical processes during welding, not known to this extent from literature previously.

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