Keyword type: model definition, surface interaction
With this option the surface behavior of a surface interaction can be defined. The surface behavior is required for a penalty contact analysis, it is not needed in a Mortar contact calculation. There is one required parameter PRESSURE-OVERCLOSURE. It can take the value EXPONENTIAL, LINEAR or TABULAR.
The exponential pressure-overclosure behavior takes the form in Figure
116. The parameters and
define the kind of
contact.
is the contact pressure at zero distance,
is the distance from
the master surface at which the pressure is decreased to 1 % of
. The
behavior in between is exponential. A large value of
leads to soft
contact, a small value to hard contact.
The linear pressure-overclosure behavior (Figure 117) simulates a linear relationship
between the pressure and the overclosure. At zero overclosure the pressure is
zero as well. The user has to specify the slope of the pressure-overclosure
curve and the tension value for large clearances
(should be
small, typically 0.25 % of the maximum stress expected). The value
of
, which relates to the maximum clearance for which a spring contact
element is generated can be specified too (default value
).
The tabular pressure-overclosure relationsship is a piecewise linear
curve. The user enters (pressure,overclosure) pairs. Outside the interval
specified by the user the pressure stays constant. The value
of , which relates to the maximum clearance for which a spring contact
element is generated takes the value
and cannot be changed by the user.
First line:
Following line if PRESSURE-OVERCLOSURE=EXPONENTIAL:
Following line if PRESSURE-OVERCLOSURE=LINEAR:
Following line if PRESSURE-OVERCLOSURE=TABULAR:
Example: *SURFACE BEHAVIOR,PRESSURE-OVERCLOSURE=EXPONENTIAL 1.e-4,.1
defines a distance of length units at which the contact pressure is
.001 pressure units, whereas the contact pressure at loose contact is 0.1
pressure units.
Example files: contact1, contact2.