FEA Contacts on Threaded Connections

[GSE_Dan_A]

Good afternoon everyone,

I understand the process of splitting faces and applying a Bonded Contact between the split faces when you have a bolted connection with a nut, but what kind of contacts would you use for say a threaded connection?
For example, suppose you have a plate that will be bolted to a mold.  The plate has clearnace holes for said bolts and so that the bolts are threaded into the mold to be lifted.  The plate has a threaded hole for the lifting mechanism (Swivel Hoist Ring).  Finally, the desired load is applied to the Swivel Hoist Ring and the bolts are placed in pre-tension.  I would like to simulate this via FEA but am getting tripped up in the contacts.  Also I am trying to make it as simple and efficient as possible (by eliminating any bolts or other parts that are not needed).  I use INV Pro 2014.  Can someone please provide an ideal way to simulate this as accurate as possible and as easy as possible (pictures are a bonus).  I would greatly appreciate the help.  *lets hope Hugh Henderson sees this!*

Below is an example of what I am describing above.

Regards,

[blair · Accepted solution]

I would use the Split-Face to create the area at the bottom of the four countersunk bore holes to replicate the bottom face of the socket-head allen bolts. I would use the "Ground" command to fix these four split-face surfaces and then apply the load/force to the center "bolt-face".

Standard tables will provide acceptable loads for the bolts/fasteners. You should be able to extract the loads/forces for all constraint points.

[GSE_Dan_A]

blair,

Thank you for your response.  So from what I understand I can eliminate all parts expect for the plate.  Split face the bottom of the plate (using the diameter of the SHCS head).  Fix these areas and apply my desired load to the circular face of where the Swivel Hoist Ring attaches.  My question is how do the fasteners come in to play. 

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Standard tables will provide acceptable loads for the bolts/fasteners. You should be able to extract the loads/forces for all constraint points.

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Are you saying that by looking at the Reaction Forces on the Fixed Constraint that I can determine if the bolts are able to hold the part in place?  I do have an Unbrako Techincal Manual which gives the yield, tensile, torque etc...

My other concern is the stress I get around the area that is fixed... I would imagine these stresses would not exist in the real world application (see image below).

[blair]

Yes, that is correct. In a model such as this, one could even use Symmetry and split the model into 1/2 or 1/4 if was a large model about the major axis

[GSE_Dan_A]

Thank you blair! I took your proposal and ran with it.  I did change some minor things a tad.  I set up 2 Simulations as follows...
Simulation 1 - Set up to obtain required forces to "Hold" the plate down such that there was no gap between the bottom of the plate and the Top of Mold face.  I then compared these values to what the bolts tensile force (in lbs.) was in the manual to ensure they were capable. 

Simulation 2 - I applied the forces determined in Simulation 1 to the counterbore face of the holes to simulate the pretension of the bolts.  I applied my desired load to the hole where my Swivel Hoist Ring would be.  Finally, I fixed the Mold plate along the bottom and applied a Seperation/ No Sliding constraint between the top of mold plate surface and the bottom of the Lift Plate surface. 

The result was  much like I expected.  Thanks again....