Commands list

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BC_PERIODIC

Boundary conditions

*BC_PERIODIC
"Optional title"
coid
entype${}_1$, enid${}_1$, entype${}_2$, enid${}_2$

Parameter definition

Variable
Description
coid
Command ID
entype${}_1$
Entity type of Surface 1
options: G, GS, NS, FS
enid${}_1$
Entity identification number of Surface 1
entype${}_2$
Entity type of Surface 2
options: G, GS, NS, FS
enid${}_2$
Entity identification number of Surface 2

Description

This command is used specify periodic boundary conditions. The coupled surfaces must have the same shape and discretization (a node-to-node matching is expected).

Example

Indentations in a ring

The periodic boundary condition command can be used to model cyclic symmetry. In the example below, spherical indentors are first pushed into a metal ring and then moved horizontally. By only modelling a 30 degree slice the model size and computational time can be reduced.

Full 3D model
Full 3D model
Model utilizing periodic boundary conditions
Model utilizing periodic boundary conditions
# # Model utilizing periodic BC *UNIT_SYSTEM SI # # --- PARAMETERS --- # *PARAMETER ang = 30, "ring section angle" R1 = 0.1, "ring inner radius" R2 = 0.2, "ring outer radius" h = 0.1, "ring height" Ri = 0.03, "indentor radius" ang2 = 20, "indentor position" d = 0.025, "indentation" tend = 0.01, "termination time" # # --- TIME --- # *TIME [%tend] # # --- MESH --- # *COMPONENT_PIPE "ring" 1, 1, 8, 8, 8, 0, [%ang] 0, 0, 0, 0, 0, [%h], [%R1], [%R2] *COMPONENT_SPHERE "indentor" 2, 2, 6 [0.5*(%R1+%R2)*cos(%ang2)], [0.5*(%R1+%R2)*sin(%ang2)], [%h+%Ri], [%Ri] *CHANGE_P-ORDER ALL, 0, 3 *SMOOTH_MESH ALL, 0, 45.0 # # --- MATERIAL --- # *MAT_METAL "ring" 1, 7800.0, 210.0e9, 0.3 1 *FUNCTION 1 3.0e8 + 3.0e8*epsp^0.3 *MAT_RIGID "indentor" 2, 7800.0 # *PART "ring" 1, 1 "indentor" 2, 2 # # --- BC --- # *BC_PERIODIC "ring" 1 G, 1, G, 2 *GEOMETRY_SEED_COORDINATE "surface 1" 1 [0.5*(%R1+%R2)], 0, [0.5*%h] *GEOMETRY_SEED_COORDINATE "surface 2" 2 [0.5*(%R1+%R2)*cos(%ang)], 0.5*(%R1+%R2)*sin(%ang), [0.5*%h] # *BC_MOTION "clamp ring base" 1 G, 3, XYZ *GEOMETRY_BOX 3 0, 0, -0.0001, 0, 0, 0.0001 # *BC_MOTION "indentor" 1 P, 2, XY, XY, 0, 1 V, Z, 11 V, RZ, 22 *COORDINATE_SYSTEM_FIXED 1, 0, 0, 0 1, 0, 0, 0, 1, 0 *FUNCTION 11 -smooth_v(%d, 0, %tend/10) *FUNCTION 22 -smooth_v(0.5*pi*(%ang-%ang2)/180, %tend/10, %tend) # # --- CONTACT --- # *CONTACT "all to all" 1 ALL, 0, ALL, 0 *END