Numerical Simulation of Welding Induced Residual Stresses in a Circular Hollow Section T-Joint

2006 ◽  
Author(s):  
Suraj Joshi ◽  
Cumali Semetay ◽  
John W. H. Price ◽  
Herman Nied
Keyword(s):  
Residual Stresses ◽  
Cross Sections ◽  
Mining Industry ◽  
Welding Process ◽  
Civil Structures ◽  
Element Analysis ◽  
Hollow Section ◽  
3 Dimensional ◽  
Circular Hollow Section ◽  
Intense Heat

Heavily welded circular hollow cross sections (CHS) are a common feature in civil structures such as draglines used in the mining industry and other off-shore structures. The sheer mass of the weldment and the application of intense heat generated during the welding process give birth to significant residual stresses in the structure. Often, residual stresses are high enough to act to accelerate factors such as corrosion, crack growth and fatigue. The objective of this research investigation was to predict welding generated residual stresses in a typical CHS T-Joint using Sysweld+, a welding Finite Element Analysis software. The T-joint is the first of the four lacings welded on to the main chord of a BE 1370 mining dragline cluster (designated All) of a type which is often used in the mining industry in Australia. This work examines a massive 3-dimensional geometry, which is on a much larger scale than those examined in existing studies. The paper presents the results of the simulation of residual stresses generated during the welding process in a single weld pass and compares them with the approach used in the commonly used document R6-Revision 4, Assessment of the Integrity of Structures Containing Defects.

scholarly journals Validation of Welding Simulations Using Thermal Strains Measured with DIC

2011 ◽  
Vol 70 ◽  
pp. 129-134 ◽  
Author(s):  
Maarten De Strycker ◽  
Pascal Lava ◽  
Wim Van Paepegem ◽  
Luc Schueremans ◽  
Dimitri Debruyne
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
Circular Cross Section ◽  
Welding Process ◽  
Weld Bead ◽  
Image Correlation ◽  
Steel Tubes ◽  
Element Analysis ◽  
Strain Evolution ◽  
The Cross

Residual stresses can affect the performance of steel tubes in many ways and as a result their magnitude and distribution is of particular interest to many applications. Residual stresses in cold-rolled steel tubes mainly originate from the rolling of a flat plate into a circular cross section (involving plastic deformations) and the weld bead that closes the cross section (involving non-uniform heating and cooling). Focus in this contribution is on the longitudinal weld bead that closes the cross section. To reveal the residual stresses in the tubes under consideration, a finite element analysis (FEA) of the welding step in the production process is made. The FEA of the welding process is validated with the temperature evolution of the thermal simulation and the strain evolution for the mechanical part of the analysis. Several methods for measuring the strain evolution are available and in this contribution it is investigated if the Digital Image Correlation (DIC) technique can record the strain evolution during welding. It is shown that the strain evolution obtained with DIC is in agreement with that found by electrical resistance strain gauges. The results of these experimental measuring methods are compared with numerical results from a FEA of the welding process.

Simplified FEA Models in the Analysis of the Redistribution of Beneficial Compressive Stresses in Welds During Cyclic Loading

2018 ◽  
Author(s):  
B. L. Josefson ◽  
J. Alm ◽  
J. M. J. McDill
Keyword(s):  
Cyclic Loading ◽  
Residual Stresses ◽  
Compressive Stress ◽  
Welding Process ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Compressive Stresses ◽  
Static Contact ◽  
Weld Toe ◽  
Compressive Residual Stresses

The fatigue life of welded joints can be improved by modifying the weld toe geometry or by inducing beneficial compressive residual stresses in the weld. However, in the second case, the induced compressive residual stresses may relax when the welded joint is subjected to cyclic loading containing high tensile or compressive stress peaks. The stability of induced compressive stresses is investigated for a longitudinal gusset made of a S355 steel. Two methods are considered; either carrying out a high frequency mechanical impact (HFMI) treatment after welding or alternatively using low transformation temperature (LTT) electrodes during welding. The specimen is then subjected to a cyclic loading case with one cycle with a tensile peak (with magnitude reaching the local yield stress level) followed by cycles with constant amplitude. A sequential finite element analysis (FEA) is performed thereby preserving the history of the elasto-plastic behavior. Both the welding process and the HFMI treatment are simulated using simplified approaches, i.e., the welding process is simulated by applying a simplified thermal cycle while the HFMI treatment is simulated by a quasi-static contact analysis. It is shown that using the simplified approaches to modelling both the welding process and HFMI treatment gives results that correlate qualitatively well with the experimental and FEA data available in the literature. Thus, for comparison purposes, simplified models may be sufficient. Both the use of the HFMI treatment and LTT electrodes give approximately the same compressive stress at the weld toe but the extent of the compressive stress zone is deeper for HFMI case. During cyclic loading it is shown that the beneficial effect of both methods will be substantially reduced if the test specimen is subjected to unexpected peak loads. For the chosen load sequence, with the same maximum local stress at the weld toe, the differences in stress curves of the HFMI-treated specimen and that with LTT electrodes remain. While the LTT electrode gives the lowest (compressive) stress right at the well toe, it is shown that the overall effect of the HFMI treatment is more beneficial.

Estimation of Residual Stresses in Steel Welded Joints Using Three Dimensional Finite Element Analysis

2018 ◽  
Author(s):  
Shivdayal Patel ◽  
B. P. Patel ◽  
Suhail Ahmad
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Boundary Conditions ◽  
Welding Speed ◽  
Welded Joints ◽  
Plate Thickness ◽  
Welding Process ◽  
Element Analysis

Welding is one of the most used joining methods in the ship industry. However, residual stresses are induced in the welded joints due to the rapid heating and cooling leading to inhomogenously distributed dimensional changes and non-uniform plastic and thermal strains. A number of factors, such as welding speed, boundary conditions, weld geometry, weld thickness, welding current/voltage, number of weld passes, pre-/post-heating etc, influence the residual stress distribution. The main aim of this work is to estimate the residual stresses in welded joints through finite element analysis and to investigate the effects of boundary conditions, welding speed and plate thickness on through the thickness/surface distributions of residual stresses. The welding process is simulated using 3D Finite element model in ABAQUS FE software in two steps: 1. Transient thermal analysis and 2. Quasi-static thermo-elasto-plastic analysis. The normal residual stresses along and across the weld in the weld tow region are found to be significant with nonlinear distribution. The residual stresses increase with the increase in the thickness of the plates being welded. The nature of the normal residual stress along the weld is found to be tensile-compressive-tensile and the nature of normal residual stress across the weld is found to be tensile along the thickness direction.

Engineering Critical Assessment of Post Weld Heat Treatment for Full-Encirclement Tees Greater Than 1.25 Inches

2019 ◽  
Author(s):  
Kolton Landreth ◽  
Qi Li ◽  
Raghav Marwaha
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Critical Assessment ◽  
Material Strength ◽  
Mechanical Reinforcement ◽  
Element Analysis ◽  
Pipeline Design ◽  
Weld Heat

Abstract Full-encirclement split tee fittings for hot tapping and plugging (HT&P) wrap completely around the pipeline and are welded in place. The welded joint provides mechanical reinforcement of the pipe and branch. When full-encirclement hot tap tees are welded to pipelines 24 inches in diameter or larger, the header must often be at least 1.25 inches thick to pass the required calculations for reinforcement. This means the joint will require post weld heat treatment (PWHT) according to ASME B31.8 and CSA Z662. However, PWHT can be extremely dangerous and impractical, potentially elevating temperature to the point where material strength of the pressurized pipeline is compromised. An engineering critical assessment per ASME FFS-1/API 579 indicated PWHT may not be required for a full-encirclement hot tap tee over 1.25 inches thick. Specifically, research showed that the residual stresses developed during the welding process may not limit the design of a full-encirclement tee or lead to shorter pipeline design life. This paper illustrates how a “more rigorous analysis” per paragraph 802.2.2[b] of ASME B31.8 and paragraph 4.3.12.2 of CSA Z662 may help operators avoid the PWHT requirement. It discusses the finite element analysis (FEA) simulations researchers used to induce residual stresses in a carbon steel fitting. The residual stresses induced in the fitting were used as initial condition for plastic collapse and fatigue evaluations.

scholarly journals Numerical Analysis of Axial Cyclic Behavior of FRP Retrofitted CHS Joints

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 648
Author(s):  
Mohammad Alembagheri ◽  
Maria Rashidi ◽  
Amin Yazdi ◽  
Bijan Samali
Keyword(s):  
Numerical Analysis ◽  
Welding Process ◽  
Axial Loading ◽  
Cyclic Behavior ◽  
Buckling Mode ◽  
Compression Load ◽  
Hollow Section ◽  
Plastic Failure ◽  
Frp Composite ◽  
Circular Hollow Section

This paper aims to numerically investigate the cyclic behavior of retrofitted and non-retrofitted circular hollow section (CHS) T-joints under axial loading. Different joints with varying ratios of brace to chord radius are studied. The effects of welding process on buckling instability of the joints in compression and the plastic failure in tension are considered. The finite element method is employed for numerical analysis, and the SAC protocol is considered as cyclic loading scheme. The CHS joints are retrofitted with different numbers of Fiber Reinforced Polymer (FRP) layers with varying orientation. The results show that the welding process significantly increases the plastic failure potential. The chord ovalization is the dominant common buckling mode under the compression load. However, it is possible to increase the energy dissipation of the joints by utilizing FRP composite through changing the buckling mode to the brace overall buckling.

Strengthening of wide-flange columns under load

1990 ◽  
Vol 17 (5) ◽  
pp. 835-843 ◽  
Author(s):  
H. Marzouk ◽  
S. Mohan
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Critical Load ◽  
Closed Form Solution ◽  
Welding Process ◽  
Form Solution ◽  
Element Analysis ◽  
Welding Stress ◽  
Existing Structures ◽  
Welding Sequence

The present work deals with formulation of theoretical and analytical methods leading to the development of column strength curves. The formulations were developed for both elastic and inelastic behaviour. Two types of reinforcement have been developed for strengthening the W-shape columns under load. Since the column strength curves are based in part on the magnitude and distribution of residual stresses, it is extremely important to consider the new pattern of residual stresses due to welding process. Also, the welding sequence will affect the magnitude and distribution of residual stresses. Theoretical formulations leading to a closed-form solution for the prediction of critical load were developed for two types of strengthening using the superposition of original residual, new welding, and initial loading stresses. A nonlinear finite element analysis based on the large deformation theory of stability was used to predict the strengthened column critical load. It takes into consideration the effect of cooling residual stresses and new welding residual stresses. The formulations were incorporated with gradual penetration of yielding, the spreading of inelastic zones along the member length, the presence of residual stresses, and strain hardening of the material. Experiments were carried out to determine the actual capacity of strengthened columns. Seven specimens were tested using two and four strengthening plates. The welding stresses were measured through a series of experiments, and it was found that the parabolic distribution is a very close approximation to the actual new welding stress distribution. Key words: reinforcement of steel columns, welding stresses, welding sequence, strengthening of existing structures, buckling, steel plating, finite element.

scholarly journals Numerical Investigations on Residual Stress in Laser Penetration Welding Process of Ultrafine-Grained Steel

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Dezheng Liu ◽  
Yan Li ◽  
Haisheng Liu ◽  
Zhongren Wang ◽  
Yu Wang
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cross Section ◽  
Material Flow ◽  
Welding Process ◽  
Weld Bead ◽  
Welding Residual Stress ◽  
Element Analysis ◽  
Ultrafine Grained ◽  
Solidification Cracks

Weld solidification crack prevention in the laser penetration welding process is essential for the strength of the welded component. The formation of solidification cracks can ultimately be attributed to welding residual stresses, and preventive measures should be taken during welding. In this study, the effects of residual stresses on the laser penetration welding quality of ultrafine-grained steels were investigated. A heat source model was established through the analysis of the metallography of the cross section of the heat-affected zone (HAZ) of ultrafine-grained AN420s-grade steel, and the chemical composition of the weld bead was obtained using an FLS980-stm Edinburgh fluorescence spectrometer. Furthermore, the constitutive coupling relation between the temperature and material flow stress was established based on the Gibbs function, and the welding residual stress was obtained by setting trace points in a finite element analysis (FEA) model based on experimental data of the weld bead cross section under different welding conditions. The results show that weld solidification cracks will form when the residual stresses exceed the material flow stresses in the weld bead, and the residual stresses can be decreased through a reasonable increase of the welding speed. The results indicate that the proposed criterion has high accuracy and can be used to predict the formation of weld solidification cracks in the laser penetration welding process.

Finite Element Analysis Used to Optimize Welding Patterns for Marine Structure

1998 ◽  
Author(s):  
Dmitry Ischenko ◽  
Raafat Ibrahim
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Welding Process ◽  
Element Analysis ◽  
Gusset Plate ◽  
Transient Problem ◽  
Element Simulation ◽  
Marine Structure ◽  
Solid Plate ◽  
Nonlinear Transient

Abstract The development of optimum welding patterns which can reduce the adverse effects of welding is important for industry, and particularly, for shipbuilding. In this investigation, a finite element simulation was employed in order to optimize the design of the weldment and reduce residual stresses and distortions. A gusset plate, which was used to increase the stiffness of marine structures, was subjected to thermal loads to simulate the effect of the welding process. Temperature distributions were obtained as a solution of the nonlinear transient problem of thermal conductivity. These distributions were then used to calculate residual stresses and distortion by solving thermo-elastic-plastic problems. The results indicated a significant reduction in the distortion when a plate with circular slots and interrupted welding was used instead of a continuously welded solid plate.

Sequential Transient Numerical Simulation of Inertia Friction Welding Process

2008 ◽  
Author(s):  
Medhat Awad El-Hadek ◽  
Mohammad S. Davoud
Keyword(s):  
Temperature Distribution ◽  
Residual Stresses ◽  
Friction Welding ◽  
Welding Process ◽  
Transient Temperature ◽  
Inertia Friction Welding ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Full Field ◽  
Welding Processes

Inertia friction welding processes often generate substantial residual stresses due to the heterogeneous temperature distribution during the welding process. The residual stresses which are the results of incompatible elastic and plastic deformations in weldment will alter the performance of welded structures. In this study, three-dimensional (3D) finite element analysis has been performed to analyze the coupled thermo-mechanical problem of inertia friction welding of a hollow cylinder. The analyses include the effect of conduction and convection heat transfer in conjunction with the angular velocity and the thrust pressure. The results include joint deformation and a full-field view of the residual stress field and the transient temperature distribution field in the weldment. The shape of deformation matches the experimental results reported in the literature. The residual stresses in the heat-affected zone have a high magnitude but comparatively are smaller than the yield strength of the material.

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