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Bolted Joint Contact Problem

I have an assembly model that I am trying to analyse in Catia 5 - 18. I need to simulate a bolted joint so that I can see the stress patterns in the bolts.
The model consists of two parts with four clearance holes. The two parts are held together by four studs fitted through the clearance holes. The studs have nuts on both ends.
I have followed the example of a bolted joint in the training documentation that I have:
1.contact property between the two parts.
2. contact properties between all 8 nuts and the two parts.
3. Smooth connection between the inner cylindrical surfaces of the nuts on one side of the joint and cylindrical areas on the studs (to fix the nuts to the studs)
4. Bolt tightening connections between the inner cylindrical surfaces of the nuts and the surface of the studs on the other side. 300kN applied.
5. Clamp applied to the sides of one part to prevent it from moving.
6. User defined restraints in the outer faces of the nuts to prevent them from sliding.
7. User defined restraint on the non-clamped part to prevent it from sliding on the clamped part.
I started from the bottom up with this assembly, testing a single bolt joint, then a two bolt joint. It worked fine.
Now I apply the same principles to the 'real' model with four studs the analysis fails with the following error:
Factorization failed in contact computation. Absolute pivot number 3249 is negative or null. Value : -5.634e-017.
Possible causes
1. contact elements are coinciding.
2. A contact element is clamped.

I have rebuilt this model three times, re-applying all of the connections and constraints each time. Every time it fails with the same error.

I can't understand why it works with one and two studs, but not four.

Does anyone know where I can get hold of an example analysis model with two parts held together with four studs with nuts on both ends please?

I can't use virtual bolts. The purpose of the analysis is to examine the stress patterns in the studs.
Thanks.
 
Ball Joints are circular course, which are utilized generally within vehicles inorder to interface the control arms to the guiding knuckles. Ball joint are made of steel and they comprise of a course stud and attachment encased in a packaging.

These Ball joints are utilized as turn between the wheels and the suspension of a car. Swiveling appendages are recognized in front and back suspension of different autos. The instrument behind Ball Joints assists in unhindered development in two planes in the meantime.
 
Ball Joints are circular course, which are utilized generally within vehicles inorder to interface the control arms to the guiding knuckles. Ball joint are made of steel and they comprise of a course stud and attachment encased in a packaging.

These Ball joints are utilized as turn between the wheels and the suspension of a car. Swiveling appendages are recognized in front and back suspension of different autos. The instrument behind Ball Joints assists in unhindered development in two planes in the meantime.
 

nura209333

New member
Try with user defined constrains

CATIA was designed to approach the mass model. Not specific one. So, sometimes, ground reality and mass model didn't find same path. In this topught, i am giving somewhat little solution to your problem. You can put resptrains with USER DEFINED CONSTRAINS.

In this case, pls give restrains with clear idea of axis & DOF of parts.

Best of luck.
 

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