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!SPRING_D

Definition of spring with specified degrees of freedom.

For the two nodes connected by a 2-node connector element (element type 511), a spring connecting the degree of freedom DOF1 of node 1 and the degree of freedom DOF2 of node 2 is defined. The direction of the spring is determined by the degree-of-freedom numbers and does not follow the deformation of the model. To define a spring acting along the axis connecting the two nodes, use !SPRING_A.

Node 1 and node 2 here are the first and the second node given as the connectivity of !ELEMENT.

Definition in the Mesh Data

!SPRING_D gives the spring constant as a material property; it does not create a spring by itself. The following two definitions are required in the mesh data (msh).

  • An element of type 511 whose connectivity is the two nodes connected by the spring (see !ELEMENT)
  • A section with TYPE=INTERFACE for that element group (see !SECTION). Give as MATERIAL the name of the material whose spring constant is defined by this keyword

Parameter

None

** 2nd Line or later **

Define spring coefficient for specified degrees of freedom. Write one line for each pair of degrees of freedom; springs for several pairs can be defined by writing several lines.

    (2nd line) DOF1, DOF2, SPRING_COEFF
Parameter Name Attributions Contents
DOF1 I Degree of freedom number for node 1 (1,2,3)
DOF2 I Degree of freedom number for node 2 (1,2,3)
SPRING_COEFF R Spring constant

Example of Use

When connecting node 1 and node 2 with a different spring constant in each of the x, y and z directions

msh

!ELEMENT, TYPE=511, EGRP=ESPRING
1, 1, 2
!SECTION, TYPE=INTERFACE, EGRP=ESPRING, MATERIAL=SPRING1
1.0

cnt

!MATERIAL, NAME=SPRING1
!SPRING_D
1, 1, 100.0
2, 2, 300.0
3, 3, 400.0

Note:

  • When different degree-of-freedom numbers are given to DOF1 and DOF2, the spring connects the displacement of node 1 in one direction with the displacement of node 2 in another direction. To obtain a spring acting in the same direction, give the same number to DOF1 and DOF2.
  • No stiffness of this spring is added to the degrees of freedom for which no spring is defined. Write all the required pairs, or constrain them by boundary conditions.
  • A material with a spring constant is treated as a material dedicated to connector elements. The same material name cannot be shared with solid elements by also giving elastic properties to it.
  • !SPRING_D is a spring of a connector element connecting two nodes. It differs in purpose from !SPRING, which is a boundary condition that elastically supports a node against the ground.