{"id":285203,"date":"2023-05-23T01:45:49","date_gmt":"2023-05-23T01:45:49","guid":{"rendered":"\/forum\/forums\/topic\/difference-between-spg-idam1-and-mat_add_damage\/"},"modified":"2023-05-23T01:45:49","modified_gmt":"2023-05-23T01:45:49","slug":"difference-between-spg-idam1-and-mat_add_damage","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/difference-between-spg-idam1-and-mat_add_damage\/","title":{"rendered":"Difference between SPG IDAM=1 and MAT_ADD_DAMAGE"},"content":{"rendered":"

I have a small question (may be stupid?). I am modeling material MAT_024 with a yield stress equal to 5.5 MPa. I want to simulate material brittle fracture using the SPG method and I tried two methods for the definition of material failure criterion:<\/p>\n

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  1. First method is to define IDAM=1 and very small plastic failure strain (say e_f = 0.0001). In that case failure occurs but it seems that bonds between particles are not fully broken. A situation occurs where plastic deformations continue to grow even after the bond is broken. At the same time, the material in the failed zone continues to behave as if it were bonded. Why does this happen? As I understood the SPG mechanism should completely break the bond when reaching the fracture criterion (in this case e_f=0.0001) and a crack should form in the material.<\/li>\n
  2. The second method is to define MAT_ADD_EROSION (in addition to MAT_024) with criteria of maximum equivalent stress (SIGVM = 5.5 MPa). In that case, I use IDAM = “Programm controlled” in ANSYS Workbench (as I understand it is IDAM=0). The result is a very brittle fracture with no material further deformation and particles are clearly disconnected from each other after failure. Maybe it is appropriate but I can not understand why there is such a big difference with the First method if the SPG bond break mechanism remains the same?<\/li>\n
  3. Also, I cannot display the fracture zone in LS-PrePost in the Second method since equivalent stress decreases after a fracture. In the First method I used plastic strain bounds (e_p > 0.0001) to change the color of particles with failed bonds. But in 2nd case I can not visualize the zone of destruction, since equivalent stress can’t be the criteria for coloring because of decreasing the value after fracture. What can I do in that case? <\/li>\n<\/ol>\n

    Thank you in advance!<\/p>\n","protected":false},"template":"","class_list":["post-285203","topic","type-topic","status-closed","hentry","topic-tag-ansys-ls-dyna-1","topic-tag-ansys-workbench-ls-dyna"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t