{"id":462722,"date":"2026-08-18T23:15:41","date_gmt":"2026-08-18T23:15:41","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ls-dyna-and-ls-prepost-contact-variables-question\/"},"modified":"2026-08-18T23:15:41","modified_gmt":"2026-08-18T23:15:41","slug":"ls-dyna-and-ls-prepost-contact-variables-question","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ls-dyna-and-ls-prepost-contact-variables-question\/","title":{"rendered":"LS-Dyna and Ls-PrePost Contact Variables Question"},"content":{"rendered":"

Hello all!<\/p>\n

I’m currently extracting several variables from my model where several bodies contact one another with a near-frictionless penalty-based contact (*CONTACT_AUTOMATIC_SINGLE_SURFACE<\/code>). I’m trying to compare contact variables to an experimental reference where they report peak pressure, mean pressure, and contact area gathered using Tekscan pressure films. I have some questions that I hope someone else has experience with.<\/p>\n

    \n
  1. If two different parts are in contact, should both parts have the same contact pressure, force, and area readings? I have a force transducer on each of the two contacting parts, and I found that the forces from RCFORC agree pretty much exactly, but the results for pressure and contact area were close (~5 to 20% difference) and not exactly the same. Is this related to the mesh or element density, or could it point to something wrong in my contact setup? If it is just discretization, is there a recommended convention for which side to report or to average both sides?\n<\/li>\n
  2. I noticed that I have access to several “pressure” variables in LS-PrePost, so I’m wondering what each variable represents and which could be better suited to my purpose:
    a) “Pressure” from d3plot, which I guess could be hydrostatic pressure
    b) “Interface Pressure” from intfor, obtained using a transducer
    c) “Peak Pressure” from intfor, after setting NPRESU to 3 on *DATABASE_EXTENT_INTFOR<\/code><\/li>\n<\/ol>\n

    I compared these three variables across several simulations and the values were close, but not exactly the same. Is any of these options better to compare against a pressure film? Also, what’s the difference between peak pressure and just taking the maximum value of interface pressure at a given state?
    3. Related to the above, I also need contact area for the same comparison. Would anyone know how LS-PrePost computes the “Contact Area” quantity? Is there a threshold being used to sum elements or does it add all elements with nonzero values?<\/p>\n

    Thanks in advance for any guidance!<\/p>\n

    Best, <\/p>\n

    Andres<\/p>\n

     <\/p>\n","protected":false},"template":"","class_list":["post-462722","topic","type-topic","status-publish","hentry","topic-tag-contact"],"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