spherical screw and helical wheel

[enrico1979]

Hi, guys.

We laugh.
I'm at a dead point.
I am trying to simulate endless screw gear, helical toothed wheel.
the problem, with transient and that at the rotation of the screw, with frictional contact between the teeth, I can not correspond the rotation of the toothed wheel, problem that would not exist if I used two toothed wheels. I insert the necessary joints, using for the endless screw also the command(apdl) that binds rotation and translation, but nothing.
Has anyone ever dealt with that problem? ?
Could you direct me? ? ?
Unfortunately it is still early to venture with the classic (less challenging analysis, or better static I can do, but not more), I like the solution of a structural that actually reads me of contacts between the teeth where these actually do not occur, generating unbelievable solutions.

thanks and good day to all.

 

[eih64]

I don't know what your goal is. So you don't want to simulate real contact but do you want a motorcycle law between the two?

 

[enrico1979]

Excuse me, I'll explain.
I would like to know the tension that, given a strong moment on the wheel, and the rotation speed of the endless screw (driven by a motor) comes to act on the teeth in hold (then in fact the contact).
Now, with regard to the law of motion, I was advancing the decisive hypotheses that would allow to simulate the real going of the mechanism, from which however to reach the above solution, that is the tension on the intake teeth (wheel side and screw side).

thanks in advance eih64,

Nb:
I opted at the moment for a static simulation, (satisfying for my boss and I am flunked for now), but that I don't think you answer the reality, that I would like to investigate.

 

[eih64]

as you have already been able to understand the problem is related to contact. It might be helpful to see some pictures. during the simulation there are some files that allow you to understand what is happening and then the actions to take. helping you with so little information is difficult.

 

[enrico1979]

thanks for the availability eih64.

I try to explain and tell you how I think I've come to a solution I hope plausible.
I have a helical wheel pushed by an endless screw that allows the azimuthal handling of the solar tracker that I am accupating. the norm of wind loads imposes destructive tests carried out by us on the machine in which the part that yields before (even before what should) is precisely the toothed wheel (the teeth are literally cut). These wheels are designed by us, even if it is my company that has given the limit load to which the teeth should have kept. Unfortunately, I realized, (from pro dynamics of pro and ) that the axial f on the unending screw was very high and therefore I managed to have the geometry of the gear to try to understand what is the resistance of the teeth and in particular if they hold to the value for which they were designed (value, I think however underestimated, that it would ensure the seal of the machine under wind conditions that the ipone norm).
returning to the simulation, I opted for a static structural, using a chant of type frictionless between the teeth (augumented lagrange), with a cylindrical support on the toothed wheel (fixed axially), and two cylndrical support on the ends of the screw where this is via supported bushings (with one side locked axially and one no). I obviously stuck the mesh in the contact area.
Now, although the dof nn are 0 and it is a statical, the result seems to be consistent with the trials of destruction made (I also did a previous analysis, where with a fixed support, instead of one of the two cylindrical, I got similar results).
What do you say? ? ?
Can I trust the post, using such presetting? ?