Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

Oasys LS-DYNA Environment: User Guide (Version 8.1)
for individual surfaces.
Note that SST, MST, SFST, SFST, SFMT (see *CONTACT) do not apply to types 3, 5 and 10.
If SHLTHK on *CONTROL_CONTACT is non-zero, MAXPEN is ignored and PENCHK is
always 1.
Contact types 4, 13, 14, 15, 16, a3, a5, a10
For these contact types, the contact depth is always limited by element thickness:
shell elements:
thk = min [shell thickness, .4 x min side length, .5 x sqrt (area)]
or thk = user-defined value SST, MST if non-zero.
solid elements:
thk = min [volume/area, .5 x sqrt (area)]
Contact type 26
This contact type uses a segment thickness of 400 times the shell thickness. Spurious penetrations
are avoided because the slave node “remembers” from which side it entered the segment.
CONTACT ON SHELLS: SURFACE OFFSET
The following applies to all single surface contact types, plus types a3, a5, a10, 14, 16:
For contacts on shell elements, impacting nodes first feel a resisting force when half a thickness
from the plane of the shell element. Normally the resisting force is sufficient to maintain the
node in this position, but if the node were forced to continue its motion, the force would rise as
the node approached the element, then reverse as the node crossed to the other side of the
element, reducing to zero as it passed beyond half a thickness from the element. Thus the
thickness of the shell is accounted for, and contact from both sides of the element is permissible.
NOTE:Shell elements may not be initially coincident if they are to contact each other. They
should be offset by the shell thickness.
For contact types 3, 5, 8, 9 and 10, to which the above does not apply, an impacting node first
feels a resisting force as it crosses the plane of the element. If the node were forced to continue
its motion, the resisting force would increase until the maximum penetration depth is reached
(see CONTACT DEPTH above). Contact can occur from one side only; this is determined by
segment orientation, if the surface is defined by segments, or by initial gap if either the surface
is defined by parts or shell elements or ORIEN on *CONTROL_CONTACT is set to 2. Thus
initial gaps are unnecessary ONLY if the surface is defined by segments and ORIEN is 1 or 0.
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