0 Replies Latest reply on Feb 4, 2010 3:51 AM by 1-ON0XJM

    Unlike results

      • Let's open the file "solido_solido"
        and consider the structure formed by a horizontal plate (extrusion 1) and a vertical one (extrusion 2).


      1.What is the difference, in the calculations, if between the two extrusions you tick or not the option
      unite the result?
      The vertical plate is loaded with a force F
      1 of 20 kg on the upper surface and F2 = 1400 kg on the vertical side. According to my calculations, on the side of the union between the two plates, the results should be:


      A
      1 = 2000 mm2 = 20 cm2 surface on which you apply F1


      σc1z = F1/A1 = 20/20 = 1 Kg/cm2 uniform compression


      A2 = 14000 mm2 = 140 cm2 surface on which you apply F2


      τy = 3/2x F2/A2 = 1.5 x1400/140 = 15 Kg/cm2 max cut


      vertical plate height = 140 mm = 14 cm


      Mfx = 1400x7 = 9800 kg cm


      sez 100x20 side on which it operates Mf


      Wx = 1/6x100x202 = 6667 mm
      3 = 6.667 cm3


      σfz = 9800 / 6.667 = 1470 Kg/cm
      2 bending tension nearby the edge of the face between the two plates


      Results:


      σz = σc1z + σfz = 1 + 1470 = 1471 Kg/cm
      2


      τy = 15 Kg/cm
      2


      Von Mises => σtot = √ (14712 +3 x152) = 1471 Kg/cm2 ≈ 147 N/mm2 along the posterior side.


      the results do not coincide.


      Besides: if i have to thicken the mesh near the area of the union between the two plates:

          1. Is it better to thicken the mesh on the border (on the edges) as shown in the study "sonda_bordo" or on the sides as shown in the study "sonda_facce"? In this case the risults do not coincide between them as well. Why? Does it depend on the size of the mesh?

          2. I wanted to apply the h_adaptive method, but the results here were still different. Why?

          3. In the three studies I carried out I used the value 0.01 as the tolerance of the mesh. Is it enough to improve the precision since the size of the mesh is already small enough?

             

          • Let's open the file "shell_shell"


        5. I wanted to carry out the study by transforming the two plates into shell. I extended the vertical surface on the horizontal one to make contact and I drew the imprint of the vertical surface on the horizontal one to insert a division line and create a congruent mesh on the separation line between the two surfaces. The imprint should be a closed sketch, so how should it be drawn? Is it right if the sketch is composed of a rectangle with base 100 mm and width 10 mm, or can not be drawn and therefore the study can not be executed this way? I fixed the following size for the mesh: 4 mm (since I referred to the relationship plate thickness/4-5) and tolerance 0.01: is it right in order to have a good degree of precision?

      • open the file "shellorizz_solido"

        6. Let's suppose that the study "shell_shell" cannot be carried out because the sketch cannot be executed, I transformed only the horizontal plate into shell. I added an extrusion to the vertical one to draw a sketch and project it on the other plate_shell (in order to have always a congruent mesh on the contact zone). The results are much more different, and even with the large displacement option.