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!DASHPOT_D¶
Definition of a dashpot with specified degrees of freedom.
For the two nodes connected by a 2-node connector element (element type 511), this defines a dashpot connecting degree of freedom DOF1 of node 1 to degree of freedom DOF2 of node 2. The dashpot direction is determined by the degree-of-freedom numbers and does not follow deformation of the model. Because a dashpot contributes only to the damping matrix, it is used in implicit dynamic analysis (!SOLUTION, TYPE=DYNAMIC with idx_eqa=1 in !DYNAMIC). It has no effect in static analysis. To define a dashpot acting along the axis connecting the two nodes, use !DASHPOT_A.
Here, node 1 and node 2 are the first and second nodes, respectively, in the connectivity specified by !ELEMENT.
Definition in the Mesh Data¶
!DASHPOT_D specifies the damping coefficient as a material property; this keyword alone does not create a dashpot. The following two definitions are required in the mesh data (msh).
- An element of type 511 whose connectivity consists of the two nodes connected by the dashpot (→
!ELEMENT) - A section with
TYPE=INTERFACEfor that element group (→!SECTION). ForMATERIAL, specify the name of the material whose damping coefficient is defined by this keyword
When solid elements and connector elements are mixed, use separate element groups and define !SECTION for each.
Parameters¶
None
** 2nd line and subsequent lines **
Specify the coefficient of the dashpot with specified degrees of freedom. Write one line for each pair of degrees of freedom; multiple pairs can be assigned dashpots by writing multiple lines.
| Variable name | Attribute | Description |
|---|---|---|
| DOF1 | I | Degree-of-freedom number of node 1 (1,2,3) |
| DOF2 | I | Degree-of-freedom number of node 2 (1,2,3) |
| DAMPING_COEFF | R | Damping coefficient |
Example¶
When defining a dashpot connecting node 1 and node 5, mixed with solid elements (element group ESLD), and assigning different damping coefficients in the x, y, and z directions
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_D
1, 1, 100.0
2, 2, 300.0
3, 3, 400.0
Notes¶
- A dashpot contributes only to the damping matrix. In static analysis (
!SOLUTION, TYPE=STATIC), it does not contribute to the stiffness matrix and therefore has no effect. - If different degree-of-freedom numbers are specified for
DOF1andDOF2, the dashpot connects one direction at node 1 to a different direction at node 2. To define a dashpot in the same direction, specify the same number forDOF1andDOF2. - A material for which a damping coefficient is defined is treated as a material dedicated to connector elements. It cannot be shared with solid elements by assigning elastic properties to the same material name, so use a different material name from that of the solid elements.