/SPRING

Block Format Keyword Describes the spring elements. It used for modeling connection. The spring properties are apply on the local spring coordinate system.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/SPRING/part_ID
sprg_ID node_ID1 node_ID2 node_ID3 node_ID4 node_ID5 node_ID6      

Definitions

Field Contents SI Unit Example
part_ID Part identifier of the block

(Integer, maximum 10 digits)

  
sprg_ID Element identifier

(Integer)

  
node_ID1 Node identifier 1 for spring

(Integer)

  
node_ID2 Node identifier 2 for spring

(Integer)

  
node_ID3 Node identifier 3

(Integer)

  
node_ID4 Node identifier 4

(Integer)

  
node_ID5 Node identifier 5

(Integer)

  
node_ID6 Node identifier 6

(Integer)

  

Comments

  1. The identifier must be unique in each element family, but it is advised for each element type to have a unique element identifier in the global model.
  2. More than one spring block can be used to define a part.
  3. Any number of springs can be defined in one block.
  4. Spring elements with /PROP/TYPE8 (SPR_GENE) may have a length equal to 0.
  5. Spring elements with /PROP/TYPE12 (SPR_PUL) and /PROP/TYPE13 (SPR_BEAM) should have a non-zero length.
  6. Spring element is defined with two nodes: node_ID1 and node_ID2.
    The plane XY is defined with the three nodes (node_ID1, node_ID2, and node_ID3); the third node, node_ID3 defines the Y direction also for the non-symmetric spring (/PROP/TYPE13).

    spring_element_10
    Figure 1.
  7. The /SPRING card is also used to define /PROP/TYPE45 (KJOINT2) joints. For each joint type, node_ID1 and node_ID2 are used to define the joint itself. node_ID1 must be attached to one rigid body and node_ID2 to another rigid body. These nodes can be non-coincident, but for better behavior of the joints, it is strongly advised to use initially coincident nodes. Optional nodes node_ID3, node_ID4 are used for definition of local coordinate systems on two sides of joint. Initially the coordinate systems are coincident. Behavior of the joint is determined by relative motion/rotation of these local coordinate systems.
  8. For spherical and rigid joints only node_ID1 and node_ID2 are required. Local coordinate system of the joint is initially defined with node_ID1, node_ID3 and node_ID4 or with the global coordinate system (if node_ID3 and node_ID4 are node defined).

    ball
    Figure 2. Spherical Joint
  9. For revolute, cylindrical, translational and planar joints, node_ID3 is used to define the first axis of the joint coordinate system. If node_ID3 is not specified, the axis of the joints is defined using the line between node_ID1 and node_ID2. In this case, the nodes should not be coincident.

    revolute
    Figure 3. Revolute Joint

    translational
    Figure 4. Translational Joint

    cyl
    Figure 5. Cylindrical Joint

    planar
    Figure 6. Planar Joint
  10. For universal and free joints, node_ID3 and node_ID4 are used to define the first and the second axis of the joint coordinate system.

    universal_joint
    Figure 7. Universal Joint
  11. When joint properties are non-isotropic (not the same stiffness, friction or damping for each non-blocked DOF), a full definition of local coordinate systems is required. In this case the first axis of the local coordinate system is defined by node_ID3, the second axis of the local coordinate system is defined by node_ID4, and the third axis is computed automatically.
  12. Both node_ID5 and node_ID6 are reserved for future use for new joints types.