The following is a general set of recommendations for modeling of structural impact. Some of these recommendations will result in additional CPU costs as compared to a run where default values are used. These recommendations will not overcome fundamental modeling deficiencies such as poor meshing, inappropriate constraints, etc.
Basic remarks:
Shell Element Selection: Avoid or minimize use of triangular elements. (See *CONTROL_SHELL)
Solid Element Selection: Avoid or minimize use of tetrahedrons, pentahedrons. (See *CONTROL_SOLID)
*CONTACT
Use only “_AUTOMATIC” type contacts, e.g., *CONTACT_AUTOMATIC_SINGLE_SURFACE.
Set SOFT on optional card A to 1.
For contact treatment of angular (sharp-edged) surfaces, SOFT=2 is generally very effective.
For problematic shell-edge-to-shell-edge or beam-to-beam contact situations, use *CONTACT_AUTOMATIC_GENERAL.
*CONTROL_HOURGLASS, *HOURGLASS
For formulation 16 shells, set the hourglass type to 8.
For other shell element formulations, set the hourglass type to 4.
*CONTROL_SHELL
If triangles are intermixed with quads in any shell part, set ESORT to 1.
Set BWC=0 and PROJ=1 (for shell type 10).
*CONTROL_SOLID
If tetrahedrons or pentahedrons are used (not recommended) and these shapes are intermixed with hexahedrons in any solid part, set ESORT to 1.
*CONTROL_ENERGY
Set all parameters to 2 so that all energies are computed.
Include *DATABASE_GLSTAT, _MATSUM, _SLEOUT commands so that energies are reported.
*CONTROL_CONTACT
As a starting point, set NSBCS to zero or leave blank so that the default bucket sorting interval is used. This default value is dependent on the contact type chosen.
If small penetrations are reported in the messag file, set IGNORE=1. IGNORE can also be set using *CONTACT.
*SECTION_SHELL
If triangles are used (not recommended), set ESORT to 1.
If inelastic/plastic response of the shell part is expected, set NIP to a minimum of 3.
Set SHRF to 5/6 (0.833).
*MAT
For plasticity models where strain rate effects are invokes, set the parameter VP=1 (invokes viscoplastic strain rate formulation).
