Passing force, surface-surface contact, axis fly away

[nagypetern95]

Hello Guys,

My problem is simple an axis that is forced to move along x axis a wheel that is should push to the arc, and the result.

In theresult the axis disappears because of the displacement caused by the force. I set up surface to surface contact and the simulation model "Mes with nonlinear metarial models".

Can anybody tell what else I should do?

On the end actually I want to calculate the force to Z direction that can generate Torque. The purpose of this test is actually to determine when the wheel would not want to move downwards this is why it is so close to the x axis of the circle (Arc segment)

Thank You!

[nagypetern95]

BTW I am a student , this might be the reason why I ask probably something obvious. 

Searchin the help I foud the contact surface as a reason passing force, so I dont understand what its is.

[nagypetern95]

capture rate I increased to 100 but still he axis flys off, the contact verified one more time that the right surfaces are coupled, with valid friction values.Hmm now no clue.

[AstroJohnPE]

I suggest that you look at the results at the first time step to try to understand what is happening.

The first possibility is something like this:

1. The parts are not in contact at time 0. (The software doesn't calculate what is happening at time 0.)
2. At the first time step, a force is applied which tries to accelerate the axis (F=m*a). During that time interval, with an acceleration of F/m, the part moves some large distance X.
3. Since the distance X is large compared to the gap, the software decides that the axis cannot be in contact. The result is the axis flies away.
4. The solution is apply the force slowly until contact is established, and then ramp it to the full load. Alternatively, increase the "Contact Interaction Distance" so that it is larger than the large distance X.

The second possibility is that contact is detected, but the force becomes larger than what the mathematical contact can hold. In this case, you should see the axis and wheel make contact for a time step or two, then fly apart. The solution in this case is to increase the contact stiffness.

Please refer to the Help documentation for how to access the "Contact Interaction Distance" and contact stiffness for the version of the software that you are using.

[nagypetern95]

Thank you, I am going to try it.

[nagypetern95]

Hello,

After lots of trials and errors and changes I maneged to have output acceptable, however it didnt work with frictional contact.

Now all elements are positioned that way that it touches immadiately so there is no gap.

I am still eperimenting on the frictional contact, next week will write if I succeed.

Thanks for the help so far.