Nonlinear Shock and Vibration Element Property
Description: Specifies the nonlinear properties of a shock and vibration element (CBUSH1D entries).
Format:
Example:
Alternate Format and Example:
| Field | Definition | Type | Default |
|---|---|---|---|
| PID | Property identification number that matches the identification number on a PBUSH1D entry. | Integer > 0 | Required |
| TFKID | Identification number of a
TABLEDi entry that defines a nonlinear elastic spring element in terms of a force versus displacement relationship.
F(u) = FT(u) Tension is u > 0 and compression is u < 0. |
Integer > 0 | Required |
| TFBID | Identification number of a TABLEDi entry that defines a nonlinear viscous element in terms of a force versus velocity relationship.
F(v) = FT(v) Tension is v > 0 and compression is v < 0. |
Integer > 0 | Required |
| TFCID | Identification number of a
TABFV entry that defines stiffness-damping coupling in terms force versus displacement tables at constant velocity. See Remark 1.
F(u,v) = FT(u,v) |
Integer ≥ 0 | 0 |
| TFCIDi | Identification numbers of TABLED4 entries that define stiffness-damping coupling in the form of a power series. See Remark 1. | Integer ≥ 0 | 0 |
| F0 | Preload. | Real | 0.0 |
Remarks:
- There are two displacement/velocity-dependent forms that may be used to define the nonlinear stiffness and damping characteristics of this element. In each the displacement
u and velocity
v are the relative displacement and relative velocity with respect to grid point GA. In the first form the force versus velocity/displacement relationship is given by:
where the force due to stiffness Fk(u) is given by TFKID, the force due to damping Fb(v) is given by TFBID, and the force due to stiffness-damping coupling Fc(u,v) is given by TFCID which defines force versus displacement data for a constant velocity.
Term Field Table Type Fk(u) TFKID TABLEDi Fb(v) TFBID TABLEDi Fc(u,v) TFCID TABFV In the second form the force versus velocity/displacement relationship is given by a power series of the form
which may be further reduced to
where
and
Term Field Table Type Fk(u) TFKID TABLED4 Fb(v) TFBID TABLED4 Fc(u,v) TFCID TABLED4 - Values on the TABLEDi entry are for tension and compression. If table values F(u) are provided only for positive values u > 0, then it is assumed that F(-u) = -F(u).