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[marco.ballotta.2]

Hello,

I have been doing this exercise for Hertzian contacts:

/courses/index.php/courses/hertz-contact-mechanics/

I have followed strictly, step by step, everything that was said and showed in the videos and read the parts for the analytical problem and final verification.

My results are quite surprising, because the contact pressure and the force reaction are perfect; however, if I plot the maximum principal stress or the minimum principal stress (that are sigma_r and sigma_z in the analytical solution) the values are incredibly high. 

Also, I can't use the APDL command that is given to calculate the contact area; the solver says that there is an error solving that solution. I have a recent version of Ansys, maybe that is the cause?

I look forward for your opinions.

P.S: I tried to solve the model with pure penalty and gave me the exact same results that of augmented lagrange.

[Naresh Patre]

Hello @marco

Let me check this course example and get back to you.

- Naresh Patre

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[marco.ballotta.2]

Hello Naresh,

thank you, I apprecitate. Actually I think i have resolved my issue with that, because now the stress profile of the analytical solution and the FEM solution are more or less coincident, so it should be good.

If you don't mind, I would I ask for your advice about another case: I have been doing also the cylinder on plane contact in 3D, using the Hertz contact for concentrated force per unit length (line pressure); I created a rectangular prism as the base and a quarter of cylinder with a equivalent surface pressure. The results I obtain are similar to the analytical solution but then are a little far. Here is the image of the stress distribution.

I tried to modify the solver method (Pure penalty and augmented lagrange), I improved the mesh, I put a lot of effort but the results, as you can see, cannot match exactly the analytical solution. Is there something else I can try?

Really thanks.