Fatigue Analysis of Penetration Assembly Joined by Multi-Pass Welding

2010 ◽  
Vol 452-453 ◽  
pp. 317-320
Author(s):  
Hong Li ◽  
Li Li ◽  
Ren Fu Wang
Keyword(s):  
Residual Stresses ◽  
Transient Temperature ◽  
Random Wave ◽  
Remaining Life ◽  
Wave Load ◽  
Dynamic Stresses ◽  
Welded Structures ◽  
Time Dynamic ◽  
Transient Temperature Field ◽  
Damage Law

Due to high centralized instantaneous heat input in the process of the welding, a great deal of residual stresses and distortions should be brought in the welded structures, which can heavily influence the capability and reliability of the structure. Residual stresses and welding fatigue behaviors of stainless steel penetration assembly joined by multi-pass welding are studied in this paper. The distribution of transient temperature field and real-time dynamic stresses field in the welded region must be calculated first. Based on the residual stresses, the random wave load putting on the structure and fatigue factors, according to Miner fatigue damage law, some fatigue behaviors such as fatigue life and remaining life are obtained.

Welding Behavior Analysis of Stiffened Stainless Steel Structure

2008 ◽  
Vol 385-387 ◽  
pp. 413-416
Author(s):  
Hong Li ◽  
Hui Long Ren
Keyword(s):  
Stainless Steel ◽  
Three Dimensional ◽  
Steel Structure ◽  
Transient Temperature ◽  
Remaining Life ◽  
Whole Process ◽  
Transient Temperature Field ◽  
Damage Law ◽  
Residual Strains ◽  
Nonlinear Behaviors

Welding residual plastic strains and residual stresses are the product of complicated nonlinear behaviors of the structures during welding. The residual strains and stresses for stiffened stainless steel structure and welding fatigue analysis are studied in this paper. The three-dimensional transient temperature field is analyzed by FEM first. Doing the welding experiment for fundamental model is to verify the numerical results, the infrared thermograph is used to follow and record the whole process. The results of FEM are supported by experimental data. Then, the elastic-plastic-model is established to analyze the residual strains and stresses. Based on the stresses, loading and fatigue factors, according to Miner fatigue damage law, some fatigue behaviors such as fatigue life and remaining life are obtained.

Analysis of Nonlinear Heat Transfer and Residual Stresses during Multi-Pass Welding of Penetration Assembly

2009 ◽  
Vol 417-418 ◽  
pp. 149-152 ◽  
Author(s):  
Hong Li ◽  
Li Li
Keyword(s):  
Residual Stresses ◽  
Three Dimensional ◽  
Transient Temperature ◽  
Butt Welding ◽  
Time Dynamic ◽  
Transient Temperature Field ◽  
Dimensional Finite Element ◽  
Nonlinear Transient ◽  
Girth Welds ◽  
Three Dimensional Finite Element

Welding residual plastic strains and stresses cause errors during the assembly and reduce the strength of the structure. Based on an elastic-plastic-model, a three-dimensional finite element numerical simulation of multi-pass butt welding of a representative penetration assembly is carried out in this paper. The nonlinear transient temperature field and the real-time dynamic stresses field during multi-pass butt welding with girth welds are obtained. In the end, the residual stresses of the complicated stainless steel penetration structure are calculated by FEM software ANSYS.

Influence of Welding Conditions on Residual Stresses of Multi-Pass Tube Sheet Welds

2012 ◽  
Vol 525-526 ◽  
pp. 349-352
Author(s):  
Hong Li ◽  
Yong Zheng ◽  
Li Li
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Tube Sheet ◽  
Element Analysis ◽  
Time Dynamic ◽  
Welding Sequence ◽  
Welding Line

Residual stresses and residual plastic strains of the welded structures are the products of nonlinear behaviors during welding. The residual stresses will cause errors during the assembly of the structure and injure the beauty of appearance of the structure. Based on an elastic-plastic-model, finite element numerical simulation of a representative tube sheet penetration assembly with loop welding line joined by multi-pass welding is carried out and the influence of welding conditions on residual stresses of the tube sheet welds is studied in this paper. Nonlinear three dimensional transient temperature fields and real-time dynamic stresses field are analyzed by FEM. The heat source is modeled as a moving heat flux following a double ellipsoid distribution and the temperature-dependent properties of materials are considered. The method of birth and death of element in finite element analysis is applied to simulate the gradual growth of weld pass metal. It is shown that welding sequence, size of groove welding and weld toes dressing will obviously change the magnitude of the residual stresses of tube sheet welds.

Simulation of Nonlinear Heat Transfer and Residual Stress for Multi-Pass Welding

2010 ◽  
Author(s):  
Hong Li ◽  
Hongliang Li ◽  
Xiang Gao ◽  
Yongliang Ni
Keyword(s):  
Numerical Simulation ◽  
Welding Process ◽  
Base Plate ◽  
Transient Temperature ◽  
Time Dynamic ◽  
Transient Temperature Field ◽  
Welding Line ◽  
Welding Sequences ◽  
Temperature Dependent Properties ◽  
Girth Welds

Welding residual plastic strains and stresses of welded structures are complicated and they will cause errors during the assembly of the structure and reduce the strength of the structure. Based on an elastic-plastic-model, a 3D finite element numerical simulation of a representative penetration assembly with loop welding line is carried out in this paper. The method of join for penetration structure and base plate is multi-pass welding. The transient temperature field and the real-time dynamic stresses field of the structure are obtained due to different welding sequences during multi-pass welding. In the process of analysis, the heat source is modeled as a moving heat flux along girth welds following a double ellipsoid distribution and the temperature-dependent properties of materials are considered. Being compared with the analysis results of other’s and the theory study, which provide instruction to the numerical simulation of welding process on similar components, the simulated results show mostly conformity.

Transient Temperature During the Vaporization of Liquid on a Pulsed Laser-Heated Solid Surface

1996 ◽  
Vol 118 (3) ◽  
pp. 702-708 ◽  
Author(s):  
H. K. Park ◽  
X. Zhang ◽  
C. P. Grigoropoulos ◽  
C. C. Poon ◽  
A. C. Tam
Keyword(s):  
Thin Film ◽  
Solid Surface ◽  
Elevated Temperatures ◽  
Bubble Nucleation ◽  
Transient Temperature ◽  
Specular Reflectance ◽  
Transient Temperature Field ◽  
Excimer Laser Pulse ◽  
Nanosecond Time Resolution ◽  
Laser Heated

The thermodynamics of the rapid vaporization of a liquid on a solid surface heated by an excimer laser pulse is studied experimentally. The transient temperature field is measured by monitoring the photothermal reflectance of an embedded thin film in nanosecond time resolution. The transient reflectivity is calibrated by considering a temperature gradient across the sample based on the static measurements of the thin film optical properties at elevated temperatures. The dynamics of bubble nucleation, growth, and collapse is detected by probing the optical specular reflectance. The metastability behavior of the liquid and the criterion for the onset of liquid–vapor phase transition in nanosecond time scale are obtained quantitatively for the first time.

Analysis of circumferentially welded thin-walled cylinders to study the effects of tack weld orientations and joint root opening on residual stress fields

2009 ◽  
Vol 223 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
N U Dar ◽  
E M Qureshi ◽  
A M Malik ◽  
M M I Hammouda ◽  
R A Azeem
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Arc Welding ◽  
Operating Conditions ◽  
Stress Fields ◽  
Welded Structures ◽  
Prime Concern ◽  
Thin Walled ◽  
Tack Weld ◽  
Welding Processes

In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or structural loads) are becoming more stringent, putting immense pressure on welding engineers to secure excellent quality welded structures. The local, non-uniform heating and subsequent cooling during the welding processes cause complex thermal stress—strain fields to develop, which finally leads to residual stresses, distortions, and their adverse consequences. Residual stresses are of prime concern to industries producing weld-integrated structures around the globe because of their obvious potential to cause dimensional instability in welded structures, and contribute to premature fracture/failure along with significant reduction in fatigue strength and in-service performance of welded structures. Arc welding with single or multiple weld runs is an appropriate and cost-effective joining method to produce high-strength structures in these industries. Multi-field interaction in arc welding makes it a complex manufacturing process. A number of geometric and process parameters contribute significant stress levels in arc-welded structures. In the present analysis, parametric studies have been conducted for the effects of a critical geometric parameter (i.e. tack weld) on the corresponding residual stress fields in circumferentially welded thin-walled cylinders. Tack weld offers considerable resistance to the shrinkage, and the orientation and size of tacks can altogether alter stress patterns within the weldments. Hence, a critical analysis for the effects of tack weld orientation is desirable.

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

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