Nonlocal material models of integral type are based on replacement of
certain suitable local quantity in local constitutive law by their
nonlocal counterparts, that are obtained as weighted average over
some characteristic volume. The weighted average is computed as a sum
of a remote value multiplied by weight function value. The weight
function typically depend on a distance between remote and receiver
points and decreases with increasing distance. In some cases, it is
necessary to disregard mutual interaction between some points (for
example if they are on the opposite sides of a thin notch, which
prevents the nonlocal interactions to take place). The barriers are
the way how to introduce these constrains. The barrier represent a
curve (in 2D) or surface (in 3D). When the line connecting receiver and
remote point intersects a barrier, the barriers is activated and the
corresponding interaction is not taken into account.
Nonlocal barrier records
Currently, the supported barrier types are following:
- Polyline barrier
||(num#)(in) vertexnodes #(ia)
||[xcoordindx #(in)] [ycoordindx #(in)]
This represents a polyline barrier for 2D problems. Barrier is a
polyline, defined as a sequence of nodes representing vertices.
The vertices are specified using parameter vertexnodes array,
which contains the node numbers. The optional parameters
xcoordindx and ycoordindx allow to select the plane
(xy, yz, or xz), where the barrier is defined. The xcoordindx is the
first coordinate index, ycoordindx is the second. The default values
are 1 for xcoordindx and 2 for ycoordindx, representing barrier in xy plane.
- Symmetry barrier
||(num#)(in) origin #(ra)
||normals #(ra) activemask #(ia)
Implementation of symmetry barier, that allows to specify up to three planes (orthogonal ones) of symmetry.
This barrier allows to model the symmetry of the averaged field on the boundary without
the need of modeling the other part of structure across the plane of symmetry.
It is based on modifying the integration weights of source points to take into account
The potential symmetry planes are determined by specifying orthogonal right-handed coordinate system,
where axes represent the normals of corresponding symmetry planes.
Parameter origin determines the origin of the coordinate system, the normals array
contains three components of x-axis direction vector,
followed by three components of y-axis direction vector (expressed in global coordinate system).
The z-axis is determined from the orthogonality conditions.
Parameter activemask allows to specify active symmetry planes; i-th nonzero value activates the symmetry barrier for plane
with normal determined by corresponding coordinate axis (x=1, y=2, z=3).