RWALL

Bulk Data Entry

RWALL – Rigid Wall for Geometric Nonlinear Analysis

Description

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

(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

Field	Contents
SID	Load set identification number. No default (Integer > 0)
RWTYPE	Rigid wall type. PLANE – Infinite plane. CYL – Infinite cylinder of diameter DIA. SPHER – Sphere of diameter DIA. PARAL - Parallelogram. Default = PLANE (PLANE, CYL, SPHERE, or PARAL)
SLID	Sliding flag. SLIDE – Sliding. TIED – Tied. SLFRIC – Sliding with friction. Default = SLIDE (SLIDE, TIED, or SLFRIC)
GSID1	Grid set ID defining slave grids to be added to the rigid wall. (Integer > 0)
GSID2	Grid set ID defining slave 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 slave search. Initially the slave 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 (See comment 3). Default = 0 (Integer = 0, 1, 2, or 3) 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).
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)

Comments

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 slave 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 IFILT ≠ 0, the tangential friction forces in each slave node in contact are filtered using a simple rule:

FT = α * F'T + (1 - α) * F'T-1

where,

FT is the tangential force

F'T is the tangential force at time t

F'T-1 is the tangential force at time t-1

α is the filtering coefficient

IFILT = 1 – α = FFAC

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

IFILT = 3 – α = 2 / 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.