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.

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.

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.

Prediction of Welding Residual Stresses, Crack Initiation and Creep Crack Driving Forces C(t) Within a Continuous Finite Element Solution

2010 ◽  
Author(s):  
D. P. Bray ◽  
R. J. Dennis ◽  
M. C. Smith
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Driving Forces ◽  
Welding Process ◽  
Creep Damage ◽  
Operating Conditions ◽  
Finite Element Solution ◽  
Element Solution ◽  
Element Analysis ◽  
Creep Crack

The work reported in this paper investigates the manufacture, through-life operation and cracked behaviour of an attachment weld in a UK AGR boiler. A structural assessment of the attachment weld was performed to demonstrate its integrity. This assessment made use of complex finite element analysis of both the welding process and postulated defects. A simulation of the welding process was performed in order to predict the residual stresses and hardened material state throughout the attachment weld. The welding simulation was performed in two stages since a butter weld was deposited prior to the attachment weld itself. The accumulation of creep damage was predicted during steady normal operating conditions for the lifetime of the component. A contour map of creep damage was used to postulate the location and size of hypothetical single and double edge surface cracks within the weld. These postulated cracks were then explicitly introduced into the finite element model. The crack tip stress parameter C(t) was evaluated in order to predict the creep crack driving forces. The results from a cracked body simulation suggested that the creep crack driving force C(t) reduces as the crack grows, due to relief of the dominant welding residual stresses. The residual stress, creep damage and cracked body simulations have been brought together into a novel continuous finite element solution. The results can be used to support a safety case for continued operation of existing plant.

Numerical Study of Welding with Trailing Heat Sink Considering Phase Transformation Effects

2014 ◽  
Vol 875-877 ◽  
pp. 2118-2122
Author(s):  
Shirish R. Kala ◽  
N. Siva Prasad ◽  
G. Phanikumar
Keyword(s):  
Finite Element ◽  
Phase Transformation ◽  
Residual Stresses ◽  
Material Properties ◽  
Heat Sink ◽  
Numerical Study ◽  
Gaussian Model ◽  
Welding Process ◽  
Source Model ◽  
Element Analysis

Welding process with trailing heat sink for 2 mm mild steel plates has been analyzed to estimate distortion and residual stresses using a finite element modeling software Sysweld. The material properties used for the analysis are both temperature dependent and phase dependent. A transient thermal analysis is carried out using Goldak double ellipsoidal heat source model and heat sink as Gaussian model with negative heat flux. The finite element analysis (FEA) is conducted by considering the material properties of all phases of steel as well as without phase transformation i.e. by considering properties of only ferrite phase. Temperature distribution, distortion and residual stresses are calculated and compared for four cases: without phase without cooling, without phase with cooling, with phase without cooling and with phase with cooling. It is found that FEA without phase transformation effects overestimates the residual stresses in the fusion zone (FZ) and heat affected zone (HAZ). It is also found that a trailing heat sink reduces transverse compressive residual stresses thus minimizing the possibilities of buckling.

scholarly journals Thermo-mechanic and Microstructural Analysis of an Underwater Welding Joint

2016 ◽  
Vol 21 (2) ◽  
pp. 156-164 ◽  
Author(s):  
Pedro Hernández Gutiérrez ◽  
Francisco Cepeda Rodríguez ◽  
Jose Jorge Ruiz Mondragón ◽  
Jorge Leobardo Acevedo Dávila ◽  
Martha Patricia Guerrero Mata ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Microstructural Analysis ◽  
Welding Process ◽  
Temperature History ◽  
Welding Parameters ◽  
Pipe Material ◽  
Element Analysis ◽  
Underwater Welding

Abstract The aim of this research is to present a comparative analysis between theoretical and experimental thermal fields as well as a microstructural behaviour and residual stresses applying multiple weld beads in the joint of two API 5L X52 pipe sections. The thermal field, microstructural and residual stresses were numerically modelled through the finite element method (FEM) and compared to experimentally. The simulation conditions used in the FEM analysis were similar considerations to the underwater welding conditions. The finite element analysis was carried out, first by a non-linear transient thermal analysis for obtaining the global temperature history generated during the underwater welding process. Subsequently, a microstructural behaviour was determined using the temperatures distribution obtained in the pipe material by calculating the structural transformations of the material during the welding process, and finally a stress analysis was developed using the temperatures obtained from the thermal analysis. It was found that this simulation method can be used efficiently to determinate with accuracy the optimum welding parameters of this kind of weld applications.

Finite Element Analysis of Residual Stresses in TT-Welded Joint of a Fixed Jacket Platform

2006 ◽  
Author(s):  
Kh. Rostami ◽  
A. R. M. Gharabaghi ◽  
M. R. Chenaghlou ◽  
A. Arablouei
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Thermal Stresses ◽  
Welded Joint ◽  
Welding Process ◽  
Element Analysis ◽  
Welded Steel ◽  
Buckling Strength ◽  
Structural Distortions ◽  
Weld Toe

Welded steel tubular joints are the kind of connections used extensively in the construction of fixed jacket platforms. The welding process creates considerable tensile residual stresses near the toe of TT-joint due to the rapid cooling and contraction of final welding layers. Welding produces thermal stresses that cause structural distortions, which influence the buckling strength of the structure. In this study thermal elasto-plastic analysis is carried out using ANSYS finite element techniques to evaluate the thermo-mechanical behavior and the residual stresses of the TT-joint. Moreover, the technique of element birth and death is employed to simulate the weld filler variation with time in TT-joint. The results show the considerable tensile residual stress near the weld toe that it may cause crack initiation in this region and threats the fatigue life of joint.

Effect of Thermal Input on Finite Element Predictions of Welding Residual Stresses

2011 ◽  
Vol 399-401 ◽  
pp. 1976-1983
Author(s):  
Ai Hui Wu ◽  
Stavros Syngellakis ◽  
B. G. Mellor
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Welded Joint ◽  
Welding Process ◽  
Mechanical Analysis ◽  
Two Dimensional ◽  
Distribution Modelling ◽  
Element Simulation ◽  
Key Factor ◽  
Dimensional Finite Element

A two-dimensional finite element simulation of a welding process is developed for predicting temperature histories and residual stresses in a structural steel butt-welded joint. The purpose of the simulation presented in this paper is the assessment of the effect of uncertainties in thermal material, loading and constraint input on both the thermal and mechanical analysis predictions. The model is validated by comparison with previously welded and tested specimen with published residual stresses measurements. Residual stress results are not sensitive to the thermal analysis input even if the latter has significant influence on temperature distribution. Modelling boundary conditions for both thermal and stress analyses, was identified as a key factor affecting predictions of residual stresses and distortion.

scholarly journals Welding Simulation Used in the Design of Metallic Armor Systems

2014 ◽  
Vol 996 ◽  
pp. 518-524
Author(s):  
Lee Fredette ◽  
Elvin Beach
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Finite Element Simulation ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Welding Process ◽  
Welding Simulation ◽  
Finite Element Software ◽  
Element Simulation ◽  
Wide Range

Welding steel armor reduces the armor materials protection capability. Several industrial and military welding standards exist for welding armor materials with the primary focus on joint strength rather than ballistic integrity.The Heat Affected Zone (HAZ) created by the welding process introduces vulnerabilities in the protection system. The process and designs that we have demonstrated include mitigation features that eliminate the ballistic degradation and provide uniform protection across all armor materials.In this study we used finite element simulation of the welding process to perform trade studies evaluating welded joint designs, and to show how the designs could be altered to both optimize armor performance and reduce welding heat input. A beneficial effect of reduced heat input was the corresponding reduction in welding-induced residual stresses, an overall reduction in assembly distortion in the assembly, and improvement of the armor performance.The simulated welding process included the creation of the heat affected zone and the development of residual stresses in the structure. ABAQUS finite element software was used for the simulation with the aid of an extensive material property database created over the wide range of welding temperatures.The finite element simulation predictions were validated and verified with excellent results by metallography and micro-hardness measurements. Live-fire ballistic tests were used as the final proof of measurable design improvements. Finite element welding simulation was shown to be an effective tool for improving upon standard welded armor designs, and above all in improving human safety.

Finite Element Simulation for Residual Stresses in Weling Process

2007 ◽  
Vol 353-358 ◽  
pp. 1915-1918
Author(s):  
He Yu ◽  
Shou Ju Li ◽  
Ying Xi Liu
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Plastic Material ◽  
Yield Criterion ◽  
Welding Process ◽  
Material Model ◽  
Element Simulation ◽  
Elastic Plastic Material ◽  
Von Mises ◽  
Raphson Iteration

Owing to localized heating by the welding process and subsequent rapid cooling, the residual stresses can arise in the weld itself and in the base metals. The prediction procedures of the residual stresses in welding process were presented by using finite element techniques. The bilinear elastic-plastic material model based on Von Mises yield criterion was developed. The material non-linearity of weldment and welding fluid was dealt with using an incremental technique. Inside each step, the Newton-Raphson iteration method was utilized. A fully coupled thermo-mechanical two-dimensional analysis was performed with finite element method. The model applied in this study adopts the technique of element birth and death to simulate the weld filler variation with time in multi-pass welded joints. The effects of welding speed on residual stresses are discussed.

FE Simulation Methods to Predict Welding Residual Stresses

2012 ◽  
Vol 525-526 ◽  
pp. 281-284
Author(s):  
Li Li ◽  
Khurram Asifa ◽  
Hong Li ◽  
Shehzad Khurram
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Fe Simulation ◽  
Welding Process ◽  
Simulation Methods ◽  
The Novel ◽  
Simulation Techniques ◽  
Element Simulation ◽  
Further Development ◽  
Simplification Techniques

The purpose of this review paper is to summarize the novel and advanced finite element simulation techniques devised in recent years to predict the welding residual stresses. The finite-element (FE) simulation methods are commonly used to predict the thermal, material, and mechanical effects of welding because of their efficiency and flexibility. This study presents an overview of the research, conducted to more accurately simulate the welding process. Some recommendations and simplification techniques presented by researchers are also discussed in this study which provides a foundation for further development in this field.

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