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Mpi { OwnedByFaceOwner } // default
}
[1] The sliding with friction constraint is designed to force a set of nodes to move over
a surface. The constraint perpendicular to the surface is treated using a master-slave
formulation. The resistance to sliding within the plane is treated with a stick-slip friction
model. When the node is sliding, the friction factor ff is computed using this expression
A
ff = fk + (fs − fk ) A+d
where fk is the kinematic friction factor, fs is the static friction factor, A is a characteristic length (derived from fitting available test data), and d is the cumulative slip
resulting from slippage computed during the simulation. The three parameters are specified in the command:
SlidingWithFriction ’sff’ ’kff’ ’A’
The node and the corresponding point on the surface stick together as long as the
tangential inplane force Ft does not exceed the maximum friction force Fmax = ff Fn ,
where Fn is the force normal to the surface. When Ft exceeds Fmax , the node starts
slipping and the friction force is progressively reduced because of accumulated slippage
according to the formula above. A constraint can return to the ’stick’ status if tangential
forces cannot maintain slipping. In this case, the cumulative slippage is NOT reset to
zero. Warning: the current logic does not allow for a node to transition from one face to
an adjacent face.
WARNING: this constraint uses a mixed formulation: the motion normal to the
surface is imposed using master-slave constraints. It has not been possible to treat
both formulation correctly and the internal forces in the perpendicular direction are not
accounted properly. This algorithm may have some errors for high strain rates.
[2] In MPI executions, node-face constraints are distributed over the processors. Two
options are available: 1) the processor that owns the face also owns the constraint, 2) the
constraint is owned by the processor that owns the node. The first option is the default.
//
Fixed cylindrical surface
TrngFaceNodeBondList BNDS {
NodeList NODS // <ndL NODS>
FixedCylSurface {
ssm 0.0012
csm 0.00015
nsm 0.5 mm
pnt 0. mm
dir 0. 0. 1.
rad 5 mm
tol 0.0 mm
}
}
The detection of the node-face pairs is automatically done. It is a good idea to check that
the detection process found all the pairs. This is done in interactive mode by selecting
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