Contact thickness

Home » Knowledge Base » General » Contact » Contact thickness

Options for controlling the thickness of shell elements within the contact routines:

  • OPTT: the thickness per material, specified in *PART_CONTACT
  • SFT: thickness scaling per material, from *PART_CONTACT

  • SST/MST: slave/master thickness given on *CONTACT card

  • SFST/SFMT: slave/master thickness scaling on *CONTACT card
  • TH: default contact thickness, on the *CONTROL_CONTACT card

  • THKCHG: flag to update thickness for single surface contacts, on the *CONTROL_CONTACT card
  • SSTHK: “use actual thickness” flag for single surface contacts, on the *CONTROL_CONTACT card
  • SPOTHIN: spotweld thinning parameter, on *CONTROL_CONTACT
  • ISTUPD: flag to update shell thicknesses, on *CONTROL_SHELL

How thicknesses are initially determined:

  1. For each contact node, the contact thickness is set to the thickness of the shell element that contains it. If SFST/SFMT or SFT are set, scale the thickness (with SFT overriding SFST/SFMT). If SSTHK is 0 and the contact is single surface, limit thickness to 40% of the minimum edge length of the element.
  2. If SST/MST or OPTT or TH are set, overwrite the above with this value, with OPTT taking precedence. The limit thickness to 40% of the minimum edge length of the element is ignore for the single_surface contacts, if contact thickness is defined.

How thicknesses are updated for nodes of deformable bodies*:

ISTUPD on ISTUPD = 0 (default)
*CONTACT_AUTOMATIC_… not *CONTACT_AUTOMATIC_…
THKCHG = 0 (default) – only at first cycle
THKCHG = 1 – every cycle
SPOTHIN on SPOTHIN off (default) SPOTHIN on SPOTHIN off (default) SPOTHIN on SPOTHIN off (default)
thicknesses are scaled down near spotwelds, on the first cycle only, for nodes whose thicknesses were set in (2) above. For the other nodes, thicknesses are recomputed just as in (1) above, and scaled near spotwelds as needed. nodes not set in (2) above are recomputed as in (1) above. thicknesses are scaled down near spotwelds, on the first cycle only, for nodes whose thicknesses were set in (2) above. For the other nodes, thicknesses are recomputed just as in (1) above, and scaled near spotwelds as needed. thicknesses are not modified thicknesses are scaled down near spotwelds on the first cycle, and not modified after that thicknesses are not modified at all

*Nodes of rigid bodies are not updated.

Table of Contents