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!DASHPOT_A

Definition of axial dashpot.

A dashpot acting along the axis connecting the two nodes of a 2-node connector element (element type 511) is defined. A dashpot contributes only to the damping matrix, so it is used in implicit dynamic analysis (!SOLUTION, TYPE=DYNAMIC with idx_eqa=1 of !DYNAMIC). It has no effect in static analysis. To define a dashpot that connects specific degrees of freedom, use !DASHPOT_D.

Definition in the Mesh Data

!DASHPOT_A gives the damping coefficient as a material property; it does not create a dashpot 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 dashpot (see !ELEMENT)
  • A section with TYPE=INTERFACE for that element group (see !SECTION). Give as MATERIAL the name of the material whose damping coefficient is defined by this keyword

When solid elements and connector elements are mixed, define a separate element group and !SECTION for each.

Parameter

None

** 2nd Line **

Define axial dashpot coefficient.

    (2nd line) DAMPING_COEFF
Parameter Name Attributions Contents
DAMPING_COEFF R Damping coefficient

Example of Use

When defining an axial dashpot (damping coefficient 100) connecting node 1 and node 5, mixed with solid elements (element group ESLD)

msh

!ELEMENT, TYPE=511, EGRP=EDAMP
3, 1, 5
!SECTION, TYPE=SOLID,     EGRP=ESLD,  MATERIAL=MATERIAL1
1.0
!SECTION, TYPE=INTERFACE, EGRP=EDAMP, MATERIAL=MATERIAL2
1.0

cnt

!SOLUTION, TYPE=DYNAMIC, NONLINEAR
!MATERIAL, NAME=MATERIAL2
!DASHPOT_A
100

Note:

  • A dashpot contributes only to the damping matrix. It does not contribute to the stiffness matrix and therefore has no effect in static analysis (!SOLUTION, TYPE=STATIC).
  • A material with a damping coefficient is treated as a material dedicated to connector elements. It cannot be shared with solid elements by also giving elastic properties to it, so use a material name different from that of the solid elements.
  • An axial dashpot has damping only in the axial component. As with springs, the directions normal to the axis must be supported by other elements or by boundary conditions.