1. Introduction| Friction Stir Welding simulation tutorial
Friction stir welding involves complex material flow and plastic deformation. Welding parameters, tool geometry, etc., have important effects on the material flow pattern, heat distribution, and eventually on the structural evolution of the material. In general, the variables of the friction stir welding process are tool rotational speed, tool feeding speed, vertical pressure imposed by the tool on the workpiece, workpiece thickness, tool characteristics (dimensions, geometric shape, tool material, and tool surface coating material), deviation angle (tool angle relative to the perpendicular line of the part surface), the method of restraining the sheets, etc. In friction stir welding, the rotational movement of the tool and its friction in contact with the workpiece causes heat generation, loss of strength, and Increase in material ductility around the pin, and the feeding movement of the tool causes the material to transfer from the front of the tool to the back of it and eventually leads to join; Therefore, heat plays an important role in this process, and parameters such as rotational speed, tool feeding speed, tool geometry and etc., all somehow have a significant impact on controlling the amount of incoming heat, the disturbance and flow pattern of the material, the evolution of the microstructure and the quality of the resulted weld. In most of the implemented projects, welding mud, and welding defects (welding overfills and overlaps, weld gaps) are not visible and predictable; however, in this friction stir welding simulation tutorial, these cases are visible. This project is designed to enhance participants’ understanding of how to accurately simulate the FSW process to see the weld’s general appearance.
2. Abaqus friction stir welding (PDF File)
This Abaqus friction stir welding project shows you how to simulate the FSW process in such a way that you can accurately predict the effect of all relevant parameters on the process. The temperatures of tool and workpieces, stress distribution field, the flow of materials and appearance of welding, normal stress diagram in the path of the workpiece width, etc., are the output results of this analysis.
- In most of the implemented projects, welding mud, and welding defects (welding overfills and overlaps, weld gaps) are not visible and predictable; however, in this simulation, these cases are visible.
- The temperatures of tool and workpieces, stress distribution field, flow of materials and appearance of welding, normal stress diagram in the path of the workpiece width, etc., are the output results of this analysis.
- This project is designed to enhance participants’ understanding of how to accurately simulate the FSW process to see the appearance of welding.
Figure 1: The weld general appearance in FSW process
2.1. PROBLEM DESCRIPTION
- Example-1- FSW with consideration of the void region:
This example includes an Eulerian part (two aluminum samples and a void region) and a Lagrangian tool.
Figure 2: Geometry of the Eulerian part and Lagrangian tool in example-1
- Example-2- FSW without consideration of the void region:
This example includes an Eulerian domain (two aluminum samples) and a Lagrangian tool.
Figure 3: Geometry of the Eulerian part and Lagrangian tool in example-2
2.2. PROJECT PROCEDURES
- Setting up the software environment:
- Modeling in Abaqus: creating part and material properties, defining 3 steps of the FSW process, defining mechanical-thermal interactions, determining the initial and boundary conditions, etc.
- Submitting the job
- Viewing the results
2.3. Executing Project Procedures
- Setting up the software environment
Geometry: This example includes an Eulerian part (two aluminum samples and a void region) and a Lagrangian tool.
Steps: The analysis steps for this problem would be “Dynamic-Temp-disp”. three steps of the FSW process are:
- penetration,
- rotating (for stabilization) and
- welding (feeding).
Interactions: A friction interaction for the whole model (
= 0.42 and normal hard contact), convection heat transfer of the bottom of the samples with water (h =1000 
), convection heat transfer of other surfaces with air (h =25 ).
Boundary conditions: V1=0 for the side surfaces of the Eulerian region in the X direction, V2=0 for bottom surface of the Eulerian region, V3=0 for the side surfaces of the Eulerian region in the z direction, V2= -0.0321 m/s and VR2=95 rad/s for the tool in penetration step, VR2=95 rad/s for the tool in rotating step, V2= -2.5E-06 m/s and V3= 0.00045 m/s and VR2=95 rad/s for the tool in welding step and determining the initial temperature of 24 degrees Celsius for samples and tool.
- Submitting the job
In the job module, after creating the job, you should submit the job.
- Guidance on how to extract the results
In the video, the process of extracting the results is shown in full detail.
Figure 4: Nodal temperatures of aluminum parts
3. Workshop (Video file): A step-by-step guide on the Abaqus FSW simulation
In the Abaqus FSW simulation workshop, we selected two aluminum plates under the friction stir welding process. The workshop provides a full step-by-step guide through a video to simplify the simulation of friction stir welding.
In the video, we used three “Dynamic-Temp-disp” steps and defined all the necessary requested outputs for the FSW process. The Eulerian implementation (based on the volume-of-fluid method) was employed to model aluminum samples. In this method, aluminum material is tracked as it flows through the mesh by computing its Eulerian volume fraction (EVF) within each element. Following this, we defined the interactions between the aluminum samples and a Lagrangian tool in a reasonably simple way. Then we applied the initial and boundary conditions, such as initial temperatures, feeding, and rotational velocity. Finally, we show how to submit a job and extract the results in full detail.
It would be helpful to see Abaqus Documentation to understand how it would be hard to start an Abaqus simulation without any Abaqus tutorial.
One note, when you are simulating in Abaqus, be careful with the units of values you insert in Abaqus. Yes! Abaqus don’t have units but the values you enter must have consistent units. You can learn more about the system of units in Abaqus.
Aadhav –
What I most appreciated about this training were the comprehensive and detailed explanations regarding the key parameters of FSW and their influence on material flow patterns, temperature distribution, and ultimately, weld quality. This in-depth understanding of the welding process enabled me to optimize the process parameters more confidently to achieve high-quality welds.
Overall, this complete and comprehensive training package helped me develop advanced simulation skills for the friction stir welding process. I would recommend this training to any engineer or researcher active in the field of welding.
Experts Of CAE Assistant Group –
Thanks!