# RWALL

Bulk Data Entry Defines a rigid wall for geometric nonlinear analysis.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RWALL SID RWTYPE SLID GISD1 GSID2 FRIC DIST
G0/

X0

Y0 Z0 IFILT FFAC
X1 Y1 Z1 X2 Y2 Z2 DIA
MASS VX VY VZ

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RWALL 2 PLANE SLIDE 23 5   3
21     2 1
11 24 12
340 7 13 32

## Definitions

Field Contents SI Unit Example

No default (Integer > 0)

RWTYPE Rigid wall type.
PLANE (Default)
Infinite plane.
CYL
Infinite cylinder of diameter DIA.
SPHER
Sphere of diameter DIA.
PARAL
Parallelogram.

SLID Sliding flag.
SLIDE (Default)
Sliding.
TIED
Tied.
SLFRIC
Sliding with friction.

GSID1 Grid set ID defining secondary grids to be added to the rigid wall.

(Integer > 0)

GSID2 Grid set ID defining secondary grids to be deleted from the rigid wall.

(Integer > 0)

FRIC Friction coefficient (ignored if SLID=TIED or SLIDE).

Default = 0.0 (Real ≥ 0)

DIST Distance for secondary search. Initially the secondary nodes can be defined at a distance lower than DIST.

(Real > 0)

G0 Grid identifier defining M, definition ignores Y0 and Z0. Moving rigid wall.

(Integer > 0)

X0, Y0, Z0 Coordinates of a point M defining rigid wall location if G0 not defined. Rigid wall does not move.

(Real)

IFILT Friction filtering flag. 3
0 (Default)
1
Direct user input of filtering coefficient.
2
Filtering coefficient corresponds to a 3dB filtering level.
3
Filtering coefficient corresponds to a 3dB filtering level for user-defined frequency (frequency defined in terms of time step number).

(Integer)

FFAC Friction filtering factor.

Default = 0.0 (Real)

X1, Y1, Z1 Coordinates of a point defining M1 for RWTYPE=PLANE, CYL, PARAL.

(Real)

X2, Y2, Z2 Coordinates of a point defining M2 for RWTYPE=PARAL.

(Real)

DIA Diameter for RWTYPE=CYL or SPHER.

(Real > 0)

MASS Mass of moving rigid wall if G0 is defined.

(Real ≥ 0)

VX, VY, VZ Components of initial velocity if G0 is defined.

(Real)

1. RWALL must be selected in the subcase with RWALL=SID or by RWALADD. It can only be selected in geometric nonlinear analysis subcases which are defined by an ANALYSIS=EXPDYN subcase entry.
2. Nodal thickness of rigid wall secondary nodes is not taken into account.
3. IFILT defines the method for computing the friction filtering coefficient. Friction filtering is only available for a sliding rigid wall. If IFILT0, the tangential friction forces in each secondary node in contact are filtered using a simple rule:(1)
${F}_{T}=\alpha *{{F}^{\prime }}_{T}+\left(1-\alpha \right)*{{F}^{\prime }}_{T-1}$
Where,
FT
Tangential force
F′T
Tangential force at time t
F′T-1
Tangential force at time t-1
α
Filtering coefficient

IFILT=1 - α=FFAC

IFILT = 2 - α = 2πdt * freq, where dt = time step, and freq = FFAC

IFILT = 3 - α = 2π / N, with 1/freq = T = N * dt, and N = FFAC

4. Surface input type:
Type
Description
PLANE
MM1 defines the normal direction.
CYL
MM1 defines the axis of the cylinder.
SPHER
M is the center of the sphere.
PARAL
MM1 and MM2 define the parallelogram with the normal as cross product MM1 x MM2.
5. This card is represented as a rigid wall in HyperMesh.