spot weld with specified diameter

[prakhar5aug]

I have been trying to spot weld 2 sheets - with weld point in modelling and weld mesh in fem it works fine but i want to give the weld diameter so i have used CWELD connections it works fine with 1 mm diameter but above that it gives this error

*** USER FATAL MESSAGE 7200 (MDG2PAT)
GHA/GHB POINTS LAY OUTSIDE OF PATCH FOR CWELD/CFAST ELEMENT 2400

 

[BlasMolero]

Hello!,
The DIAMETER value represents the diameter of the weld. The diameter, length, and material are used to calculate the stiffness of the connector in 6 directions. Then nonsense of giving error when using a value bigger than 1.0 (send the FEM model to SIEMENS GTAC for inspection).

When the option SPOT WELD is on, “SPOT” is written to the TYPE field on the PWELD entry. This causes the actual length of the weld element to be ignored and instead the stiffness is calculated using an effective length (Le). Le = 1/2 (ta + tb), where ta and tb are the thicknesses of the shell elements A and B which are being connected with the weld.

Best regards,
Blas.



~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[prakhar5aug]

Hi,
I have attached the image of what it prompt when a value above 1 is entered.....

both are sheet element with thickness 1mm and 0.5mm apart

Thanks & Regards,
Prakhar

 

[BlasMolero]

Hello!,
First at all my recomenation is to update to the latest release of NX AdvSim 9.0, the version 7.5 is very old and errors could exist that are fixed with new releases.
For the NX AdvSim mesher to create a CFAST or CWELD connection at a selected location, the following conditions must be met:

• The fastener or weld diameter that you specify in the PFAST or PWELD physical property table dialog boxes must be appropriate for the geometry you are connecting.
◦ The distance between a selected point and the free edge closest to that point cannot be less than the specified weld or fastener diameter. This means that you cannot create a CFAST or CWELD connection along an edge.
◦ The distance between individual CFAST or CWELD connections cannot be less than the specified weld or fastener diameter.
• The meshes you connect must be nearly parallel. To ensure this, the software projects two normals onto two meshes within the search distance. If the angle between the normals is greater than 20°, the software does not create the connection.
• The elements around the circumference of the weld diameter must be relatively flat and not highly curved.
• You cannot edit an existing CFAST or CWELD connection. If you need to modify an existing CFAST or CWELD connection, you must delete the connection and recreate it.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[prakhar5aug]

Hi,
thanks it helped me.....
the problem was mesh size it needs to be large enough so that the weld diameter fits into it i.e. only single node should be inside of it.....and we can edit the CWELD after applying, it works fine.....