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Recent content by cirokos

  1. cirokos

    Reduce Stiffness

    Hey everyone, I am back. First of all, I would like to thank you all for helping me with this project, your tips were truly remarkable. My project is long completed now, but the research hasn't stopped. Many of you were correct in pointing out that the data was not collected properly, we did...
  2. cirokos

    Element Failure

    Sorry then. Not gonna happen again
  3. cirokos

    Element Failure

    To everyone. Thanks a lot for your help, I really do, you have given me some great advice! Unfortunately, I couldn't come to a conclusion on the problem with the model/analysis. The experiments were accurate and there is no doubt about that. I could share the code with anyone that's...
  4. cirokos

    Element Failure

    Yes, indeed shear buckles. Ansys mechanical APDL What do you mean by flat sheet?
  5. cirokos

    Element Failure

    No all of the elements appear to be approximately in the middle of the height(where the red areas are) and I want to simulate the shear deformation of the core.
  6. cirokos

    Element Failure

    Is this good ?
  7. cirokos

    Element Failure

    Hello everyone, I am modeling a structure with shell elements in mechanical APDL. My problem is that the solution stops due to excessive element distortion in very low displacements thus giving unwanted results. Elements on the edges show this problem but not on the inside. I cannot find a way...
  8. cirokos

    Reduce Stiffness

    I am not sure I understand why to do these calculations. Your point is that the number of walls changes the stiffness of the core and thus the results don't match?
  9. cirokos

    Reduce Stiffness

    Here is the test setup. The displacement is measured by the movement of the bottom crosshead. To scale the shear stress I took the force data measured from the experiment and divided it by ( L*W) length and width of the specimen. The FEM results give the force calculated at each sub-step of...
  10. cirokos

    Reduce Stiffness

    Some calculations are involved to convert the force into equivalent shear stress, deciding the force with the area of the specimen and the unit cell respectively. A model close to the experiments is possible and it's been made but I was trying to reduce the time by modeling a unit cell or a...
  11. cirokos

    Reduce Stiffness

    All the experimental data was taken the same way and was evaluated so I don't think that they are way off. I converted the force into relative stress for both the experimental data and the unit cell in order for them to be comparable. I used the unit cell because the whole model takes a lot of...
  12. cirokos

    Reduce Stiffness

    Why be the displacement data wrong? The Instron machines are equipped with an lvdt at the crosshead. Subtracting the initial position of the crosshead from all the data should give the relative displacement which is the one I use. SWComposites is correct in saying that's how most models of a...
  13. cirokos

    Reduce Stiffness

    Okay okay, I get it now. I will try to find how to implement that in my model and see the results. Thanks a lot!
  14. cirokos

    Reduce Stiffness

    yes, the applied bc simulates a rigid connection. Rigid body motion is satisfied. I am not quite sure how I could implement the idea you suggest. Adding a real constraint to simulate some kinda of stiffness?
  15. cirokos

    Reduce Stiffness

    I haven't applied spring constants (not very familiar with how they are applied), in my model I used boundary conditions (BC) to simulate the loading plates. The applied BC used to output a perfect shear loading without rigid body motion and deformed shape matched well with the experimental...
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