PBUSH1D

Bulk Data Entry Defines the linear and nonlinear properties for a one-dimensional spring-and-damper structural element.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PBUSH1D PID K B M          
  SPRING TYPE IDT IDC IDTDU IDCDU      
  DAMPER TYPE IDT IDC IDTDV IDCDV      
  GENER   IDT IDC IDTDU IDCDU IDTDV IDCDV  

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PBUSH1D 35 4.35 0.5            

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PBUSH1D 35 4.35              
  SPRING TABLE 43            

Definitions

Field Contents SI Unit Example
PID Property identification number.

No default (Integer > 0)

  
K Stiffness.

Default = 0.0 (Real > 0)

  
B Viscous damping.

Default = 0.0 (Real > 0)

  
M Total mass.

Default = 0.0 (Real > 0)

  
SPRING String indicating that a function defining the spring characteristics follows.
Tension
U > 0
Compression
U < 0

Where, U = U(GB) - U(GA) in CBUSH1D element coordinate system: GA/GB are grid points on CBUSH1D

  
DAMPER String specifying that the next 5 fields define a nonlinear viscous element in terms of a force versus velocity relationship.

(Character)

 
GENER String specifying that the next 7 fields define a general nonlinear elastic spring and viscous damper element in terms of a force versus displacement and velocity relationship.

(Character). For this element, the relationship can only be defined with TYPE=EQUAT

  
TYPE String indicating the type of definition.
EQUAT
The following fields are identification numbers of DEQATN entries.
TABLE
The following field is an identification number of a TABLEDi entry.

For GENER, TYPE = blank or EQUAT is allowed.

(Character)

  
IDT Identification number of a DEQATN entry for tension if TYPE=EQUAT.

Identification number of a TABLEDi entry for tension and compression if TYPE=TABLE.

No default (Integer > 0)

  
IDC Identification number of a DEQATN entry for compression if TYPE=EQUAT.

Is ignored for TYPE=TABLE.

Default = IDT (Integer)

  
IDTDU Identification number of a DEQATN entry for tension if TYPE=EQUAT.

The DEQATN entry defines the derivative of the force F with respect to the displacement, u for tension u > 0. For SPRING and GENER only, Required if TYPE=EQUAT.

No default (Integer)

  
IDCDU Identification number of a DEQATN entry for compression if TYPE=EQUAT.

The DEQATN entry defines the derivative of the force F with respect to the displacement u, for compression u < 0. For SPRING and GENER only.

Default = IDTDU (Integer)

  
IDTDV Identification number of a DEQATN entry for tension if TYPE=EQUAT.

The DEQATN entry defines the derivative of the force F with respect to the velocity v, for tension v > 0. For DAMPER and GENER only, Required if TYPE=EQUAT.

No default (Integer)

  
IDCDV Identification number of a DEQATN entry for compression if TYPE=EQUAT.

The DEQATN entry defines the derivative of the force F with respect to the velocity v, for compression v < 0. For DAMPER and GENER only.

Default = IDTDV (Integer)

  

Comments

  1. Either the stiffness K, or the damping B, or the mass M must be specified. B and M are ignored in static subcases.
  2. The SPRING continuation line is used in nonlinear analysis solution sequences only. The table input supersedes the stiffness K.
  3. PBUSH1D may only be referenced by CBUSH1D elements.
  4. PBUSH1D is supported with linear static, nonlinear static, as well as nonlinear transient analysis types, for small and large displacement cases.
  5. In all linear subcases, as well as small displacement nonlinear analysis (ANALYSIS=NLSTAT) subcases, PBUSH1D and CBUSH1D are converted internally to the equivalent PBUSH (with PBUSHT, if necessary) and CBUSH.
  6. The parameters defined on the continuation entries are used in nonlinear solution sequences only.
  7. The linear K and C are used in all solution sequences unless parameters on continuation entries are defined and a nonlinear solution sequence is used. Then, the parameters K and C are used for initial values in the first iteration of the first load step and the parameters from continuation entries overwrite the linear parameters thereafter. When SPRING or GENER are specified, K is overwritten. When DAMPER or GENER is specified, C is overwritten.
  8. If more than one continuation entry is defined, then the forces of SPRING, etc. are superposed. Multiple continuation entries of the same kind are not allowed.
  9. For TYPE=TABLE, values on the TABLEDi entry are for tension and compression. If table values are provided only for positive values arguments, then it is assumed that the function defined by the table is an odd function regarding zero.
  10. For TYPE=EQUAT, the equations for tension and compression can be different. If the identification numbers for compression are left blank, it is assumed that the same equation applied to both tension and compression.
  11. This card is represented as a property in HyperMesh.