PBUSHFX

Bulk Data Entry

PBUSHFX – Generalized Spring-Damper-Mass Property

Description

Defines the various nominal property values for a generalized spring-damper-mass structural element. This property is not affected by translational and rotational stiffness limits specified using PARAM, BUSHSTIF.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PBUSHFX	PID	K	K1	K2	K3	K4	K5	K6
		B	B1	B2	B3	B4	B5	B6
		GE	GE1	GE2	GE3	GE4	GE5	GE6
		M	M1	M2	M3	M4	M5	M6

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PBUSHFX	35	K	4.35	2.4	RIGID			3.1
		GE	0.02

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PBUSHFX	35	B	4.35
		M	1.2		7.1

Field	Contents
PID	Property identification number. No default (Integer > 0)
K	Flag indicating that the next 1 to 6 fields are stiffness values. No default (Character)
Ki	Nominal stiffness values in directions 1 through 6. If RIGID is defined, a very high relative stiffness (relative to the surrounding structure) is selected for that degree-of-freedom simulating a rigid connection. See comments 3 and 5. Default = 0.0 (Real or RIGID)
B	Flag indicating that the next 1 to 6 fields are force-per-velocity damping. No default (Character)
Bi	Nominal damping coefficients in directions 1 through 6 in units of force per unit velocity. Default = 0.0 (Real)
GE	Flag indicating that the next 1 to 6 fields are the structural damping constants. No default (Character)
GEi	Nominal structural damping constants in directions 1 through 6. GEi is ignored in transient analysis, if PARAM, W4 is not specified. See comments 3 and 5. Default = 0.0 (Real)
M	Flag indicating that the next 1 to 6 fields are directional masses.
Mi	Nominal mass values in directions 1 through 6. The Mi fields do not contribute to mass and inertia properties. Their contributions to gravity and/or centrifugal loading are also not included. Default = 0.0 (Real)

Comments

1.	All generalized spring-damper-mass property entries must have unique ID numbers.

2.	The K, B, GE, and M lines may be specified in any order.

3.	Ki, Bi, GEi, or Mi may be made frequency dependent for both direct and modal frequency response by use of the PBUSHT entry.

The nominal values are used for all analysis types except frequency response. For modal frequency response, the normal modes are computed using the nominal Ki values. The frequency-dependent values are used at every excitation frequency.

4.	To obtain the damping coefficient GE, multiply the critical damping ratio C/C0 by 2.0.

For backward compatibility with Nastran, if ONLY GE1 is specified on a PBUSH entry and GEi, i = 2 to 6 are blank on that PBUSH entry, then a single structural damping is assumed and applied to all Ki of that PBUSH. If a PBUSH entry has a GEi, i = 2 to 6 specified, then the GEi fields are considered variable for that PBUSH entry.

6.	This card is represented as a property in HyperMesh.