What are the boundary conditions that I must apply to perform a stress test on my part?

Hello, I am a mechanical engineer student. The subject of my research is to study the mechanical response of tensile probes with different infill patterns (Hexagonal honeycomb, Triangular honeycomb, Square honeycomb) and then compare the results of the simulations to define the better option for an optimal strength/weight ratio for a 3D printed part.

All specimens will be subjected to a Tensile stress test in Ansys WB using Static Structural, where I defined the same material and boundary conditions. The material is PLA. I leave images to illustrate the boundary conditions used in the simulation for the case of the probe with Hexagonal Honeycomb. The specimen's right end has a displacement of 2 [mm/min], as seen (I used tabular data to apply 2 [mm] displacement divided into 60 steps).

I would like to ask you if these are the correct boundary conditions. Because I had incorrect results with other conditions, and these seem to give acceptable results. For some reason I cannot explain when I was doing a mesh convergence study (reducing the size of my mesh elements), the values of the Stress never converged. For these conditions I used on my model, I did not experience this problem. If someone could explain to me why I had this problem, I would be very grateful. The boundary conditions that gave me such a problem where using Fixed support for the left end and a prescribed displacement or a load on the right end.

The thing is that the boundary conditions I used for the case I'm showing on the pictures should be used If the part had symmetry on those planes I applied them. And this is not my case, since the tensile probe I'm analyzing is the complete solid part and not 1/4 using symmetry for the analysis.


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