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[henriquedpires]

Hello, everyone,

Thanks in advance,

I'm currently using Inventor Nastran to try to simulate the following problem. However, I'm struggling a lot with simple tasks, so I'm here to post my problem and evaluate if ANSYS is the right fit for me and can help me out.

My geometry is a plate with 5 openings (hubs) in which 5 shafts are going to be press-fitted. There is no symmetry, and the openings have different sizes. The assembly of each shaft will produce a stress and displacement field in all other openings, which I must measure and analyze.

What I want to do is: assemble the first shaft and look at the displacement and stress field of the plate. Assemble the second shaft and reanalyze the displacement and stress field of the plate… Do the same procedure until the 5th shaft.

Using the Inventor Nastran I’m struggling to achieve good outcomes, especially for the regions of contact between the shafts and the openings. For an interference-fit in Nastran I must use a non-linear analysis and the results of the contact regions have significant perturbations that invalidate the stress field in this zone. Since interference-fit does not give me a good solution, I have tried to use a shell in the place of the shaft and apply a described radial displacement to the shell until the position I want. For this case I used a simple “separation contact” (do not allow interference) and even this way I get bad and non-physically possible results for the contact zone (with a smaller amplitude right now, but evenly relatively high). I tried using hydrostatic pressure to the shell, however, it is not realistic due to the displacement field of the plate (not uniform around the openings), so it turns out the described displacement is the best solution in my point of view (but please let me know yours).

The problem is that when I constrain a described displacement (forced movement) in Inventor Nastran I must block the same direction of the displacement I want to impose. So, in my case, I must block the radial displacement of the shell to input an actual displacement of its nodes. To impose sequential loads (1 and 2, for example) in Inventor Nastran non-linear analysis I must apply one load in one “subcase”, and both loads in the second “subcase”. This means that to get the result of the assembly of 2 shafts, I must press-fit one shaft in subcase1 and both in subcase2.

This method turns out into a problem for the 2nd, 3rd, 4th and 5th shaft assemblies in which I want to measure the actual displacement and final stress field in all the openings especially in those that already have a shaft assembled. Due to the method, for example, when I press-fit the 3rd shaft, the 1st and the 2nd shafts (shells) have the global position restricted by the constraints I must apply to apply the actual displacement and keep the load throughout the subcases for a sequential load.

Is ANSYS able to get me a clear and good solution in any possible way?

Have you faced a similar position/problem? Any idea to model this problem in ANSYS?

[1shan]

Could you have a look at https://www.youtube.com/watch?v=5jH2Ox6-YkU. You could follow the same methodology for 5 shafts, without using constraints at the holes. You could either insert all 5 at the same time or one after the other using 5 load steps. I am not sure what you mean by "For an interference-fit in Nastran I must use a non-linear analysis and the results of the contact regions have significant perturbations that invalidate the stress field in this zone." I havent used Nastran but are you talking about the penetration that occurs when you use a contact?
Regards Ishan.