Use the following option to

specify a spring element between

two nodes with its line of action

being the line joining the two

nodes:

, TYPE=SPRINGA

Abaqus/CAE Usage: P roperty or Interaction module:

SpecialSprings/DashpotsCreate, then select one

of the following:

Connect points to ground: select points: toggle

on Spring stiffness

(equivalent to SPRING1)

Connect two points: select points: Axis:

Specify fixed direction: toggle on Spring

stiffness

(equivalent to SPRING2)

Connect two points: select points: Axis: Follow

line of action: toggle on Spring stiffness

(equivalent to SPRINGA)

Stability considerations in Abaqus/Explicit

A SPRINGA element introduces a stiffness between two degrees of freedom without introducing an associated mass. In an explicit dynamic procedure this represents an unconditionally unstable element. The nodes to which the spring is attached must have some mass contribution from adjacent elements; if this condition is not satisfied, Abaqus/Explicit will issue an error message. If the spring is not too stiff (relative to the stiffness of the adjacent elements), the stable time increment determined by the explicit dynamics procedure () will suffice to ensure stability of the calculations.

Abaqus/Explicit does not use the springs in the determination of the stable time increment. During the data check phase of the analysis, Abaqus/Explicit computes the minimum of the stable time increment for all the elements in the mesh except the spring elements. The program then uses this minimum stable time increment and the stiffness of each of the