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PBUSH |
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PBUSH |
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»Click here to display Table of Contents«
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PBUSH |
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PBUSH |
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Bulk Data Entry
PBUSH – Generalized Spring-Damper-Mass Property
Description
Defines the nominal property values for a generalized spring-damper-mass structural element.
Format
(1) |
(2) |
(3) |
(4) |
(5) |
(6) |
(7) |
(8) |
(9) |
(10) |
PBUSH |
PID |
K |
K1 |
K2 |
K3 |
K4 |
K5 |
K6 |
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B |
B1 |
B2 |
B3 |
B4 |
B5 |
B6 |
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GE |
GE1 |
GE2 |
GE3 |
GE4 |
GE5 |
GE6 |
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M |
M1 |
M2 |
M3 |
M4 |
M5 |
M6 |
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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. See comments 3 and 5 . If RIGID is defined, a very high relative stiffness is selected for that degree-of-freedom simulating a rigid connection. The rigid element formulation can be controlled using SYSSETTING(PBUSHFOR). 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) |
| 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. |
| 5. | 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 (even as 0.0), then the GEi fields are considered variable for that PBUSH entry. |
| 6. | The nominal property values specified on the PBUSH entry are used on the corresponding fields (that are blank) of the PBUSHT entry. |
| 7. | This card is represented as a property in HyperMesh. |
See Also:
