Finite element analysis of residual stress induced by shot peening process (original) (raw)
Related papers
Fatigue analysis of Welded Joint with and without Shot Peening
INPRESSCO, 2016
This paper summarizes fatigue test on high strength steel specimens in the as-welded condition and specimens treated by Shot peening. Results indicate that material strength has effect, to a certain extent, on the fatigue performance of Shot peening welded joints. High tensile weld residual stress is one important factor contributing to fatigue crack development even under reversal or compressive cyclic loadings. A compressive stress induced by Shot peening is beneficial by eliminating the tensile residual stresses and generating compressive residual stresses, which improves fatigue strength of welded structures. Internal stresses were investigated on five base metal samples treated by shot peening. The induced compressive residual stresses benefit to increase the threshold value of stress intensity factor range, for fatigue crack initiation and early propagation. Shot peening was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. Shot peening could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. It is shown that Shot peening is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength.
The prediction of residual stress and its influence on the mechanical properties of weld joint
A three-dimensional metallo-thermo-mechanical analysis of bead on plate welding is performed in this work. This coupled model enables to capture the microstructural development and temperature history at local region. As a result, the residual stress is evaluated based on the temperature-dependent mechanical properties computed by the mixture of individual phase. Isotropic hardening is assumed in the finite element (FE) analysis. At the same time, the distribution of residual stress is also predicted by treating the mechanical properties as integral values of sheet metal. The two simulated fields of stress and strain after welding are analysed and compared. Moreover, as it is known that welding changes the mechanical properties of the original material, especially in fusion zone (FZ) and heat affected zone (HAZ), the stress and strain data at interested areas (HAZ and FZ) are subtracted for comparison. The predicted stress and strain fields are imported to subsequent simulation of standard tensile test. The stress-strain curves are compared with the one of base material. It is found that residual stress has significant influence on the structural performance of weld joints.
Design and analysis of welded aircraft wing panels
2005
Nowadays, increasing manufacturing cost effectiveness becomes a vital condition for the commercial success of the next generation of large wide body aircrafts. Welding is a very strong candidate process to be used in manufacturing, allowing both sensible cost reductions and structural efficiency. The main aim of the work is to study the fatigue crack propagation in welded structures. The study is focused on the effect of welding residual stresses to the damage tolerance behaviour of the structure. The welding technique under investigation is the Variable Polarity Plasma Arc (VPPA). Two stringer panels were designed, one tension panel to simulate the lower wing skin cover and one compression panel to mimic the upper wing skin cover. The main design driving force for the upper stiffened panel is buckling since it is under compression. Damage tolerance is the main design criterion for the lower stiffened panel due tensile fatigue loading. Design of the endfittings for the tension stiffened panel was also carried out using finite element modelling in order to ensure uniform stress distribution at the cross section of the test area of the structure. A fatigue analysis at the various locations of the bolts and at the weld line has been performed. This is 3 Table of Contents 4 List of Figures 7 List of Tables 12 List of Abbreviations 14 Chapter 1 Introduction 1.1 History and Applications of Aerospace Aluminium Alloys 15 1.2 The Welding Process in Aerospace Manufacturing 17 1.3 Welding Techniques 20 1.4 Description of the WELDES Research Project 24 1.5 Overview of the Thesis 25 3.3 Design of the Tension (Lower) Stiffened Panel 64 3.4 Design of the Compression (Upper) Stiffened Panel 65 3.5 Buckling Analysis of the Compression Stiffened Panel 66 3.5.1 J-Section Stringer 68 3.5.2 Z-Section Stringer 69 3.5.3 Effect of Doubler Thickness on Critical Buckling Load 70 3.6 Design of End-Fittings for the Fatigue Tests 71 3.7 Fatigue Analysis of Joints 73 3.7.1 Bolts 75 3.7.2 Weld Line 78 Chapter 4 Fatigue Crack Growth Analysis of Welded Centre Crack Tension (CCT) Coupons 4.1 Introduction 80 4.2 Finite Element Modelling Techniques used in this Thesis 80 4.2.1 Crack-Tip Singularity Models. 81 4.2.2 J-Integral Method 84 4.2.3 Virtual Crack Closure Technique (VCCT) 89 4.2.4 Comparison of Different SIF Calculation Methods 95 4.3 Description of the FE Model 98 4.3.1 Modelling of Welding Residual Stresses 98 4.3.2 Fatigue Crack Growth Modelling 102 4.4 Numerical Results 105 4.4.1 FE Results of Crack Closure in Parent Coupons 105 4.4.2 FE Results of Crack Closure in Welded Coupons 113 4.5 Prediction of Crack Propagation Life of Welded Coupons 118 4.6 Concluding remarks 120 5 able of Contents Chapter 5 Crack Propagation Analysis in Stiffened Welded Panels 5.1 FE Model Description and Modelling Strategy 121 5.2 Results of Simple LEFM Approach-(Crack Starts on the Web) 124 5.3 Large Scale Stringer Panel Study-(Crack Starts on the Skin) 132 Chapter 6 Discussion and Concussions 6.1 Discussion 135 6.2 Main Conclusions 137 6.3 Recommended future work 138 References 140
Materials
This article presents the influence of the Shot Peening (SP) process on residual stress and surface roughness of AMS 5504 joints welded using the Tungsten Inert Gas (TIG) method. Thin-walled steel structures are widely used in the aviation and automotive industries, among others. Unfortunately, the fatigue properties become worse during the welding process. Samples of 1 mm-thick AMS 5504 steel plates were first prepared using TIG welding and then strengthened by the Shot Peening (SP) process. The technological parameters of the SP process were changed in the range of time t from 2 min to 4 min and of pressure p from 0.4 MPa to 0.6 Mpa. The residual stresses were measured by X-ray diffraction in three zones: fusion zone (FZ), heat-affected zone (HAZ) and base metal (BM). The results showed that SP introduced compressive residual stresses in all of the zones measured, especially in the FZ. The greatest value of compressive residual stresses σ = −609 MPa in the FZ was observed for the ...
DETERMINATION OF RESIDUAL STRESSES OF WELDED JOINTS PREPARED UNDER
Welded joints are used for construction of many structures. Welding is a joining or repair process which induces high residual stress field, which combines with stresses resulting from in-service loads, strongly influencing in-service behavior of welded components. When compared with stresses due to service loads, tensile residual stress reduces crack initiation life, accelerates growth rate of pre-existing or service-induced defects, and increases the susceptibility of structure to failure by fracture. Also, welding residual stresses are formed in a structure as a result of differential contractions which occur as the weld metal solidifies and cools to ambient temperature.
Journal of ASTM International, 2006
Although residual stress in welded structures and components has long been known to have an effect on their fatigue performance, access to reliable, spatially accurate residual stress field data has been limited. Recent advances in neutron and synchrotron X-ray diffraction allow a far more detailed picture of weld residual stress fields to be obtained that permits the development and use of predictive models that can be used for accurate design against fatigue in aircraft structures. This paper describes a fully integrated study of the three-dimensional residual stress distribution accompanying state-of-the-art fusion welds in 2024-T4 aluminum alloy, and how it is affected by subsequent machining and service loading. A particular feature of this work has been the development of techniques allowing the nondestructive evaluation of the residual stress field in the full range of specimens used to provide the design data required for welded aircraft structures and the integration of this information into all aspects of damage tolerant design.
Materials Testing, 2014
The effect of the weld joint configuration on components has been studied, which are under service loads, under repair or construction and the residual stresses as well as the mechanical properties of the joint have been determined. For this purpose, a horizontal positioned tensile testing device and a semi-automatic MIG welding machine have been used and then the weld joints of the plates were subjected to different elastic stresses. When the temperature of the joined elements decreased to room temperature, applied elastic stresses were released. By this means, the effects of the existing tensile stresses in the joined parts and the tensile stresses created by the welding processes were investigated. The tensile stresses occurring in the joined elements were determined by using the photo-elasticity analysis method and the hole-drilling method. Also, tensile-shear tests were applied in order to determine the effect of permanent tensile loads on the mechanical properties of the joint...
Study on Residual Stress of Welded Hoop Structure
Applied Sciences, 2020
Residual stress is inevitable during welding, which will greatly affect the reliability of the structure. The purpose of this paper was to study the residual stress of the hoop structure caused by the cooling shrinkage of the weld when the outer cylinder was wrapped and welded under the condition of the existing inner cylinder. In this paper, the “method of killing activating elements” of ANSYS was used to simulate the three-dimensional finite element of the hoop structure. In the case of applying interlayer friction, the welding-forming process and welding circumferential residual stress of the hoop structure were analyzed. The blind hole method was used to test the residual stress distribution of the hoop structure, and the test results were compared with the finite element simulation results to verify the reliability of the simulation calculation method and the reliability of the calculation results. Then, the influence factors of the maximum welding residual stress of the hoop s...
Marine Structures, 2019
In some industrial applications, welding is the only alternative to join different parts. However, the major problem in welded structures is the tensile residual stresses that are inevitably produced during welding process. Surface tensile stresses can threaten the performance of the weldments as they act as an accelerant in fatigue crack initiation and failure. Shot peening is a well-known method which can enhance weldments' fatigue performance and longevity by inducing surface compressive residual stresses in order to eliminate or limit tensile residual stresses. In this study, the effect of shot peening on redistribution of multi-pass welding residual stresses was numerically and experimentally investigated on very large components typical of welded joints used in offshore wind turbine monopiles. Finite element studies were carried out using 3D welding models and random shot peening analyses. Moreover, extensive finite element analyses were conducted to study the effect of model dimensions and the number of passes on prediction of welding residual stresses. Interesting set of results showed that shot peening can be advantageous even for large components with multi-pass welded joints. Additionally, reducing the number of weld passes in finite element models could considerably lower the computational time without affecting the accuracy of results at surface regions of the models.
Influence of welding parameters on the welding residual stresses
2017
FE simulation of welds from austenitic steel was carried out in the current paper. Two different multi-pass welds were modelled. Measurements of welding residual stresses, which were found in literature, were applied for the validation of the results. The validated models were then used as basis for sensitivity analysis. The influence of differentiating the welding speed, the heat input of the weld heat source, intermediate cooling between consecutive weld-passes and welding sequence on the welding residual stresses was investigated.