## General Mechanical

#### Force distribution at contact area

• nts1209
Subscriber

Hi everyone !!!

I am doing this simulation and I got some problem.

A contact between 2 rollers.

From the ansys, I can acquire the data of pressure distribution along the roller (from Contact Tool) but I don’t know how to plot the average of force distribution along the roller (The force distribution will be supposed larger in the both ends and smaller in the middle with this model)

The pressure distribution curve in every section like in the attached image:

I also attached the ansys file

Thank you very much

• jj77
Subscriber

If you want the total force reaction at the contact just add a force reaction probe and look at the contact.

If you want individual elemental nodal forces, then I think you need an apdl snippet for post processing this (unless they are available somehow in the force reaction probe since it needs to sum them). Put the nodes in a nodal named selection and then use the NFORCE apdl command to get the nodal forces. See NFORCE for more info.

These nodal force will be printed/written under the solution information and in the solver output file (which can be seen in WB).

• nts1209
Subscriber

Thank you for your kind respond jj77.

I want to elaborate a little bit my idea. Theoretically, to get the force distribution along the roller, I have to integrate the pressure curve at the contact area which I show in the picture (or the area under the curve) to get dF/dx and I need to calculate for all sections along the roller to get the force distribution. I intend to export the data of pressure and calculate by Excel or something like that but the data of pressure distribution is very complicated so I am stuck here.

Thank you very much for your suggestion. I will find the way to use that function. Hope it can support my idea

• peteroznewman
Subscriber

• I solved your model and added a Penetration result to the Contact Tool.

• You can see that the penetration changes from .057 mm at the end to .047 mm at the center.

• This is an unacceptable variation in the performance of the contact algorithm.

• You must take corrective action and change the Penetration Tolerance in the Frictional Contact definition.

I haven't solved the model with this suggested change and it may introduce convergence difficulties, but you can't study nip mechanics with this amount of penetration error and non-uniformity in your contact results.

• nts1209
Subscriber

Thank you Peter very much for your suggestion

I am checking the penetration error and compare the results and it is still running

Have a nice weekend !

• nts1209
Subscriber

Dear Peter

I followed your recommendation, and the problem was not convergence. I also tried changing the normal stiffness (follow this discussion) but the result was not better

I am wondering the value of penetration tolerance and normal stiffness. Is there any criteria for it or we just try until get the value of penetration as small as possible, and I don't know how much that value is acceptable to continue studying nip mechanics

Thank you very much