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How to apply Preload for Surface to Surface Contact ?

Creator
Creator

Hi everyone

 

I trying to simulation Surface to Surface Contact(STSC) on double layer Plates.

 

I have 6 Spotwelding elements( consist of chexa and rbe3 Elements)

 

In order to take into account the preload generated during spot welding, I apply a load as shown in Figure 2 on the upper and lower plates at the spot welding position.

 

However, if you look at figure 3, you can see that even if the displacement is very close to zero, displacement is very strange.

 

also in figure 4, contact pressure also appear to have ambiguous results.

 

Taking these results together, I determined that the mode shape of figure 5 is also strange.

(The first mode shape must have the same phase.)

 

Therefore, I would like to advise how to implement the preload that occurs when spot welding is generated.

 

I have attached my file. Any advice would be appreciated.

 

Best regards.

 

0.Contact_test_Model.PNG1. Model Configuration(with 6 Spotwelding Elements(Chexa))1.PreLoad(At_SPotwelding).PNG2. Preload applied at Plate(Near SPOTWELDING Position)2.DisplaceMent.PNG3. Linear Static analysis results - Displacements3.Contact_Pressure.PNG4. Linear Static analysis results - Contact Pressure4.first_modeshape(with_NOPreload).PNG6.first_modeshape(without_Preload)4.first_modeshape(with_Preload).PNG5.first_modeshape(with_Preload)

 

2 REPLIES

Re: How to apply Preload for Surface to Surface Contact ?

Siemens Creator Siemens Creator
Siemens Creator

Are you applying the preload using the BOLT functionality or are you simply applying external loads above and below the spot weld (as shown)? If you are doing the latter, try the former (using BOLT functionality). In this case, also try the RBE2 to connect the bolts to the medium.

Re: How to apply Preload for Surface to Surface Contact ?

Solution Partner Experimenter Solution Partner Experimenter
Solution Partner Experimenter

I agree with @PrabuR, you should aplly the preload directly on the 3D element that represent the weld instead of the effort at each extremity. But before you need to "split" these 3D elements in two in order to have a "cut" plan in each elements.

 

Indeed when you apply a 3D bolt preload, you need to select the nodes that defines a cross section of the bolt (or weld). when you run the analisys, the solver duplicates these nodes, pulls them together in oder to create the desired preload at each end of the bolt and then sticth the nodes together.

 

This results as an internal force that is way more similar to an weld preload than the way you used.