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Simulating welds...

Vesh

New member
I have two simple bars which I want to analyse in Mechanica which are fillet welded together.

1) I have gone to "welding" under applications and made a fillet weld, although this only seems cosmetic and doesnt register any elements in FEA mode. It is also a planar piece and not a solid weld.

2) I have tried to add a weld within Mechanica but it wont get on the correct side.

How do you simulate a weld for Mechanica?

1)...
View attachment 2616


2)...
View attachment 2617
Edited by: Vesh
 
Hi,


In analysis you are not considering the strength of the weld it is allways assumed that the material fails b4 the weld. so you are not going to analyse the weld nor you are going to specify the material property of the weld.to acheive the weld use the end weld option and select the two mating surfaces.


Regards,


Deepak Bhat
Edited by: deepakbhat_nie
 
Hi,


your selection of the two surface is wrong as you have to select the two mating surface


Regards,


Deepak Bhat
Edited by: deepakbhat_nie
 
Ok cheers for that.

I am unable to do any 'end welds', only 'perimeter welds', if this matters.

Also what does the 'thickness' option do?
 
Hi,


With reference to the pic which you have uploaded I personally think thatyou have to go with the end weld and not the perimeter weld.
2006-08-24_115719_end.jpg



this pic shows how end weld works.View attachment 2620


And this pic shows how perimeter weld works.both the pics are from the PTC help you can check it yourself.


and the thickness is the thickness of the shell which acts as weld.


Regards,


Deepak Bhat
 
Vesh,

welds from pro/weld CAN be used in mechanica. these welds (orange surf)are represented as surfaces. if you want to use them in mechanica you need to give the orange surface some shell properites via >Insert >shell.
once you mesh the model you will end up with solid elements (blue)for your 3d geometry and shells (green) for the welds and links to link solids to shells.

perimeter welds and end welds are used between midurfaces or shells an NOT Solids. from what i can see i am assuming you are parts will be meshed using solids.

the pictures that Deepak posted clearly show that the parts are compressed to a midplane(shell elements)

the other option you have is to model your welds by creating a third 3d solid part (wedge)

Again perimeter welds and end welds are only good between compressed surfaces or shells.

i hope this clears any confusion.
PM me if you have more questions
Edited by: prouser1
 
Cheers for that...

I am getting fairly accurate weld results by creating the welds in Pro/weld and assignment shell elements to them as you said.

Thanks...
 
Hello,

I have the same issue with weldings. As Vesh is doing, I create them in ProWeld, and then mesh as shells in Mechanica.
Then, I preformed the analisys, but I cant understand the results. This weld butts are simulated like shells... And the stresses that I can see make no sense for me.
Even if I used better meshing, with smaller elements, the stress increase like an stress concentration.

In this page you can find more details and pictures.
Mechanical engineering other topics - Creo Elements and Welding (FEM)

I would appreciate help with that. I want to define the thickness of weldings, to be able to handle some forces in my estructure.

Thanks in advance
 
Of course! Due to singularity you cannot rely on your weld result. You can try with Extrapolation technique. Collect the stresses away from your desired point and extrapolate back to it.
 
This could be helpful for you:

http://ww3.cad.de/foren/ubb/uploads/ToTacheles/kehlnaht_fem.pdf

if some of you are interested in, I am consent to translate it...
 

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