## General Mechanical

#### Honeycomb unit cell (RVE) analysis using periodic boundary conditions

• vagraw13
Subscriber

I am not able to implement exact boundary conditions in my analysis of a honeycomb cell which is represented as a representative volume element. I tried using periodic boundary conditions using the concept of remote points and constraint equations, but I'm not sure how correct are those. The results are not making any sense and I'm also getting a warning message regarding the boundary conditions. I also used displacement rather than remote displacement. The simulation was looking good but it gave me around 2000 MPa stress with just an applied displacement of 0.2mm (the material used was Aluminum alloy from ANSYS Engineering Data). Can someone please help me understand the exact/actual boundary conditions which I should implement so that I can complete my analysis soon?

Thank you

Varun

• SaiD
Ansys Employee

Hello Varun,

What are you trying to simulate? Are you trying to simulate a uniaxial tensile test on this honeycomb RVE? If yes, then in what direction? If you are simulating a uniaxial tensile test in x-direction, then the x-displacements of the corresponding nodes on top and bottom edges will be equal to each other. But their y-displacements will probably differ due to lateral contractions.

Thanks,

Sai

• vagraw13
Subscriber

Hello Sai,

I'm applying displacement (please see the yellow arrow) to compress the HC RVE in the x-direction. Through this, I need to take out the reaction force in the members and equivalent young's modulus (a few more properties). As you mentioned about displacements in the top and bottom edges, I used the constraint equations in which the x-displacement is the same (+1 and -1 coefficient). I'll change the coefficient in y-displacement to be +1 for both the edges so that the amount of top edge displace in +ve y-direction will be the same for the bottom edge in the negative y-direction. But, my question is more about if my applied boundary conditions are correct or not for this scenario because the results are very different from remote displacement then the displacement on the right edge. Or should I apply remote displacement/displacement on the left and right edges? If so, then where should I fix my HC cell? Please help!

Thank you

Varun