Attached is tie rod dwg. I am trying to do a FEA on the tie rod but results was not what I wanted.
Anyway, I will start by explaning this tie rod. There are four tie rod that hold two platen in place. The picture shows half of a tie rod cuz I used a symmetric constraint on it. The is a platen in between the two threaded area and two nuts are holding this platen in place.
It has thread diameter of 9 1/2". So just using basic calculation with 825000 pre load on the tie rod. The stress should be around 12500 psi. But using FEA software
(creo), the lowest stress I get by changing the constraint is 52000 psi. that's way too much for the material. I am wondering if I constraint it correctly.
Here is how i constraint it, I created a region where the nuts thread contact with the tie rod thread, I put the 825000 lb on this region on every thread.
Then on the opposite side of the thread (across from the above region, ie the slope part of the thread) I put a displacement constraint to constraint any movement on XYZ translation.
I am not sure if that's enough or can someone explain to me how to constraint a thread. Plus this part is relatively large so instead of drawing the actual thread, I drew it as a cut and revolve it then pattern it. I tried drawing the nuts in but the assembly would not mesh.
If someone who is can point me to a correct direction on how u would constraint this would be great. thanks in advance
