Learning Forum

I am doing a static structural analysis on a pipe support clamp. The clamp has an upper (1) and lower section (2) that is held together with two bolts. The two mating clamp faces have a frictional contact of 0.2. The bolt head also has a frictional contact with the top clamp face, while the threaded part of the shank uses a bonded contact with the lower clamp. I have applied a 6180N pretension to the bolts. 

There are various forces applied on the clamp device:

The model:

The bolt:

The mesh:

I keep getting the errors: 

An internal solution magnitude limit was exceeded. (Node Number 158886, Body Unknown, DOF UX) 

and 

Solver pivot warnings or errors have been encountered during the solution. 

I'm not sure what is causing these errors as the other pretensions I have for the rest of the bolts in the model all allow it to solve fine. Any ideas? Thanks

[Akshay Maniyar]

Hi,

It looks like the model is experiencing a rigid body motion. Can you check the initial information by inserting the contact tool? Also, share the screenshots of loads and boundary conditions. Please check the below course on Rigid body motion for more details.

Rigid Body Motion in Contact | Ansys Innovation Courses

Thanks,

Akshay Maniyar

[dlooman]

Perhaps you could temporarily support the model while applying the bolt pretension.  Also you could use weak springs to hold the model together.  The message means that one of the parts has displaced by more than 1e6 inches/mm/meters depending on what your length unit is.

[mjmiddle]

In what load steps were these loads applied? You should not apply them all at once. For bolt pretension, you should only load the bolt pretensions in a 1st load step. Only use enough supports and displacements to hold the model from rigid body motion in that 1st load step. Then in 2nd load step and any later load steps, you can "lock" the bolt pretension and apply your other loads.