Welding with ANSYS Workbench 2

[bernardirafael]

Hello,

My name is Rafael, I am researching buttering welding analysis using ANSYS Workbench. As it was recomended, I bought the book "COMPUTATIONAL WELDING MECHANICS" [Goldak], but it hasn't arrived yet. As I am waiting for it, I'd like to know if any of you could give me some tips on this subject, beucause it seems to be really complex, not the physics itself but the ANSYS coding seems to be the biggest challenge.

Does any of you could help me on this? With articles, algorithms and others. Any help will be really appreciated!

Mainly, any help with BIRTH and DEATH use would be great!

Thanks in advance.

 

[flash3780]

Well, for starters, it depends a bit on what type of problem you're trying to solve.

For problems involving fatigue, one of the biggest challenges with welds (especially fillet welds) is determining the effect of unfused portions of the weld. These can act like cracks and really should be analyzed with a fracture mechanics approach.

On the other hand, for problems where cyclic loading is negligible, fatigue may not be an issue. Also, full penetration welds can be created in such a way to avoid crack-like defects. In the cases where crack-like defects are not present or a concern, simply modeling the weld geometry will give you a stress field which will allow the engineer to establish margins on the joint.

For large structures with many welds, modeling the weld geometry explicitly may not always be practical. In that case, loading on the weld seam can be determined from your ANSYS model and used to establish design margins. In this case, consider using an approach from literature, such as Blodgett's "Design of Welded Structures." Alternatively, sub-models can be created for areas with higher weld loading.

For material limits in welds, I have always used cast material properties to establish margins.

 

[bernardirafael]

@flash3780

Thanks for your reply!

Actually, the analysis will be based on buttering welding, so I'll probably just make some fillets and analyse the heat propagation, to compare to in real life analysis. The main problem here is not only to create the moving heat source but also use the commands Birth and Death to simmulate the material addition.

My main struggle is the Workbench coding. Even tho it has a nice interface for begginers, it is still hard for begginers to learn to code properly, and to be sure that everything is right and the output (result) is realiable.

That's why I need some help... like for example, an article showing the use of the Birth and Death commands... or even showing the algorithm... and the same for the modeling of the heat source.

Do you have any tips on this? Or do you know any article that could help me?

Thanks in advance!

 

[flash3780]

I suppose I'm not sure exactly what you're trying to learn from your analysis? Are you trying to determine how much heat you need to put into the weld to fuze the parts together properly? If so, that sounds like you're trying to do a transient thermal analysis?

Simulating a welding process might be a little bit out of my area of expertise, but if you need more control over the birth and death of elements, I think that ANSYS Mechanical APDL is a better tool for the job than Ansys Mechanical. ANSYS has it's own programming language called APDL (ANSYS Parametric Design Language) which makes it very flexible for simulating complex phenomenon such as this.

 

[bernardirafael]

Thanks for your help!

I want to analyse the affected zone size due to the welding.

Can't I use APDL commands on ANSYS Mechanical? Do I really have to use the Mechanical APDL? I am asking this because the Mechanical APDL seems to be harder to unexperienced users.

 

[flash3780]

Yes... you can use APDL commands in ANSYS Mechanical. However, I think you'll find that you'll have a much easier time with it if you use ANSYS Mechanical APDL.

ANSYS Mechanical doesn't allow you to run individual commands in a command line, so you need to run the whole analysis before you find out if your script is working properly... which makes debugging a bit of a nightmare.

So, determining the heat affected zone around a weld is definitely a transient thermal analysis problem. I think you will find that ANSYS Mechanical APDL is going to be the ideal tool for keeping track of all of your boundary conditions (these types of problems tend to have complex boundary conditions). Essentially, you'll want to create a *.inp script to apply all of your heat transfer boundary conditions to your model in a programmatic way.

 

[bernardirafael]

Thank you for these great tips! I thought that the Workbench would be the way to go... but it seems that I was wrong.

I will give it a shot and take a look on APDL scripts.

Thanks for the amazing help!