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!SPRING

Definition of spring boundary conditions

This is a boundary condition that elastically supports a specified degree of freedom of a specified node against the ground. No element needs to be defined in the mesh data. To connect two nodes by a spring, use the connector element springs !SPRING_A / !SPRING_D, which serve a different purpose.

Parameter

GRPID = Group ID
AMP = Time function name (Specified in !AMPLITUDE)
INCREMENTAL = NO (resists the accumulated displacement, Default) / YES (resists only the displacement increment)

** 2nd line or later **

(2nd line) NODE_ID, DOF_id, Value
Parameter Name Attributions Contents
NODE_ID I/C Node ID or node group name
DOF_id I Restricted degree of freedom
Value R Spring constant

Example of Use

!SPRING, GRPID=1
1, 1, 0.5

When INCREMENTAL=YES is specified for node 1 and AMP=AMP1 for node 2

!SPRING, GRPID=1, INCREMENTAL=YES
1, 1, 0.5
!SPRING, GRPID=1, AMP=AMP1
2, 1, 0.5

Note:

  • !SPRING can be used in static analysis and in implicit dynamic analysis.
  • GRPID is referred to from the LOAD line of !STEP in order to activate the spring support for each step.
  • See Functions reference: Boundary Conditions and Loads for the behavior of the spring support with INCREMENTAL and AMP.