Bolt Pretension in Ansys Workbench
Bolt Pretension in Ansys Workbench
(OP)
Morning all,
I am working on a static analysis in Ansys and have included the models of the screws so I can add pretension.
At first I added the pretension to an outer face on the screw shank. (the screw has multiple split faces on as the screw bolts 3 plates together)
Running the analysis gave me the most deflection in the bolts themselvesdue to the pretension and on investigation I could see that a hollow cylinder was stretching out from the screw. I have attached a pic to make it more clear.
I have since tried adding the pretension to the body and setting up a coord system for each bolt. The result of this was that the hollow cyclinder now stretches out of the top of the screw rather than the bottom.
Has anyone seen this before? What does it mean?
Thankyou in advance for your help
Mike
I am working on a static analysis in Ansys and have included the models of the screws so I can add pretension.
At first I added the pretension to an outer face on the screw shank. (the screw has multiple split faces on as the screw bolts 3 plates together)
Running the analysis gave me the most deflection in the bolts themselvesdue to the pretension and on investigation I could see that a hollow cylinder was stretching out from the screw. I have attached a pic to make it more clear.
I have since tried adding the pretension to the body and setting up a coord system for each bolt. The result of this was that the hollow cyclinder now stretches out of the top of the screw rather than the bottom.
Has anyone seen this before? What does it mean?
Thankyou in advance for your help
Mike





RE: Bolt Pretension in Ansys Workbench
I thick this is because of the auto scaling of the results.
Set is to true scaling.
Regards
RE: Bolt Pretension in Ansys Workbench
RE: Bolt Pretension in Ansys Workbench
Regards
RE: Bolt Pretension in Ansys Workbench
The bottom block (which in real life the bolt screws into) has a hole in it the same diameter as the bolt. The inside wall of the cylinder has a bonded contract to the outer face of the bolt (via a split face the same depth as the threaded hole)
The second block is an intermediate with a clearance hole so it is not in initial contact with the bolt. I added a no separation contact to this as the bolt was penetrating through this part during unitial simulations.
The third part is what the bolt clamps down on. There is a no separation contact between the bolt shank and the inner face of the bolt hole and a bonded contact between the underside of the screw head and the base of the counter bore.
Hope this makes sense, thanks for you help
RE: Bolt Pretension in Ansys Workbench
Did you use any other loads?
Thers is a restiction on the bolt pretension:
1 loadstep pretension the bolt (don't use any other loads in this loadstep)
2 loadstep lock the bolt pretension and apply all other loads
Hope this help.
regards
RE: Bolt Pretension in Ansys Workbench
I run the simulation with all the loads and the bolt pretentions applied.
What do you mean by loadstep? I'm quite new to ansys having only used Cosmos before.
RE: Bolt Pretension in Ansys Workbench
Under the analyse setting you need to define 2 loadstep.
Then look at the details of the bolt-pretension, a table will be availeble, load the pretension in the first loadstep a lock him in the second one, then go the the forces and set the force in the first loastep to 0.
Regards
RE: Bolt Pretension in Ansys Workbench
RE: Bolt Pretension in Ansys Workbench
RE: Bolt Pretension in Ansys Workbench
RE: Bolt Pretension in Ansys Workbench
RE: Bolt Pretension in Ansys Workbench
I'll do them all now and re run the simulation.
Thanks for your help!