Project Overview
In this example, the arc welding process on a pipe is simulated using the DFLUX subroutine in Abaqus.
A volumetric heat flux is used to simulate the welding process. The Goldak's double-ellipsoid heat source model is adopted to define the volumetric heat flux around the welding pool.
The DFLUX subroutine is used to define the Goldak's double-ellipsoid heat source and the resulting nonuniform heat flux.
Simulation of arc welding on a pipe using the DFLUX subroutine.
Circular Welding Path
The welding torch moves round the pipe in a circular path. Therefore, the position of the moving heat source changes continuously as the torch travels around the pipe.
An important point in this simulation is that the welding speed must be defined in radians per second because the heat source moves along a circular path.
Circular path of the welding torch around the pipe.
Conversion of Linear Velocity to Angular Velocity
The linear welding velocity is converted into angular velocity using the relationship between linear velocity and angular velocity.
In this model, the pipe radius is R = 0.06 m and the linear velocity is V = 0.003 m/s.
The angular velocity is therefore defined in radians per second and is used to control the circular movement of the welding heat source around the pipe.
Conversion of linear welding velocity into angular velocity.
Goldak's Double-Ellipsoid Heat Source
The Goldak's double-ellipsoid heat source model is adopted to calculate the volumetric heat flux distribution around the welding pool.
The equations of the Goldak heat source model are defined as a function of position and time, together with a number of heat source parameters.
The constants a, b, Cf, and Cr are heat source parameters that define the size and shape of the ellipses. These parameters are obtained from experimental analysis.
Goldak's double-ellipsoid heat source model used for the volumetric heat flux.
Welding and Cooling Process
The analysis is performed in two steps.
In the first step, the welding process is simulated for a duration of 125.67 seconds. During this step, the moving volumetric heat flux is applied using the DFLUX subroutine.
In the second step, the welding heat source is removed and the cooling process is simulated for a duration of 1000 seconds.
Welding stage followed by the cooling stage.
Thermal-Mechanical Analysis
Two Coupled Temperature-Displacement steps are defined for the simulation.
This analysis considers the thermal and mechanical behavior of the pipe during the welding and subsequent cooling processes.
Material Properties
The material of the pipe is Stainless-steel-SA240.
The material properties are defined as temperature-dependent properties.
- Density
- Thermal conductivity
- Specific heat
- Thermal expansion
- Elastic properties
- Plastic properties
Residual Stress Results
After the welding and cooling processes, the residual stress in the pipe is evaluated.
The results include the axial residual stress on the outside of the pipe, the axial residual stress on the inside of the pipe, and the hoop residual stress on the inside of the pipe.
Axial residual stress on the outside of the pipe.
Axial residual stress on the inside of the pipe.
Hoop residual stress on the inside of the pipe.
What You Will Learn
- How to simulate arc welding on a pipe in Abaqus.
- How to use the DFLUX subroutine for pipe welding.
- How to define a volumetric heat flux.
- How to implement Goldak's double-ellipsoid heat source.
- How to define a nonuniform heat flux using DFLUX.
- How to simulate a welding torch moving around a pipe.
- How to define a circular welding path.
- How to convert linear velocity into angular velocity.
- How to define welding speed in radians per second.
- How to use a pipe radius of 0.06 m.
- How to use a linear welding velocity of 0.003 m/s.
- How to define Goldak heat source parameters.
- How to define the parameters a, b, Cf and Cr.
- How to perform a 125.67-second welding step.
- How to perform a 1000-second cooling step.
- How to perform a Coupled Temperature-Displacement analysis.
- How to define temperature-dependent material properties.
- How to evaluate axial residual stress outside the pipe.
- How to evaluate axial residual stress inside the pipe.
- How to evaluate hoop residual stress inside the pipe.
- How to implement a Fortran DFLUX subroutine in Abaqus.
Key Features
- Arc welding simulation on a pipe.
- Circular welding path around the pipe.
- DFLUX Fortran subroutine.
- Volumetric heat flux.
- Goldak's double-ellipsoid heat source.
- Nonuniform heat flux distribution.
- Pipe radius: 0.06 m.
- Linear welding velocity: 0.003 m/s.
- Angular velocity defined in rad/s.
- 125.67-second welding stage.
- 1000-second cooling stage.
- Two Coupled Temperature-Displacement steps.
- Temperature-dependent material properties.
- Material: Stainless-steel-SA240.
- Goldak heat source parameters a, b, Cf and Cr.
- Axial residual stress results inside and outside the pipe.
- Hoop residual stress result inside the pipe.
- Research article included.
Project Information
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