How to model a viscous damper in abaqus using nonlinear dashpot element?

[TEIF-RO]

I want to use the viscous damper in abaqus. I firstly used spring/dashpot but it didn't work. Now I realized the best way is to uses the nonlinear dashpot element.
Can someone explain me how to do it?
Thanks

 

[Erik Panos Kostson]

I would look at the manual CAE user's guide, and chapter 37 related to defining dashpots.
The nonlinear properties of the dashpot can not be defined via the GUI (CAE), and needs to go in the input file as it says in that chapter.

Below is an example (spring+dashpot):

*Heading
** Job name: Job-1 Model name: Model-1
** Generated by: Abaqus/CAE Student Edition 2018
*Preprint, echo=NO, model=NO, history=NO, contact=NO
**
** PARTS
**
*Part, name=Part-1
*Node
      1,           0.,           0.,           0.
      2,  0.100000001,           0.,           0.
*Element, type=T3D2
1, 1, 2
*Nset, nset=Set-1
 1, 2
*Elset, elset=Set-1
 1,
*Nset, nset=Set-2
 1, 2
*Elset, elset=Set-2
 1,
** Section: Section-1
*Solid Section, elset=Set-1, material=Material-1
7.85398e-05,
*End Part
**  
*Part, name=Part-2
*Node
      1,  0.109999999,           0.,           0.
      2,  0.219999999,           0.,           0.
*Element, type=T3D2
1, 1, 2
*Nset, nset=Set-1
 1, 2
*Elset, elset=Set-1
 1,
*Nset, nset=Set-2
 1, 2
*Elset, elset=Set-2
 1,
** Section: Section-1
*Solid Section, elset=Set-1, material=Material-1
7.85398e-05,
*End Part
**  
**
** ASSEMBLY
**
*Assembly, name=Assembly
**  
*Instance, name=Part-1-1, part=Part-1
*End Instance
**  
*Instance, name=Part-2-1, part=Part-2
*End Instance
**  
*Nset, nset=Set-3, instance=Part-1-1
 1,
*Nset, nset=Set-4, instance=Part-2-1
 2,
*Nset, nset=Set-5, instance=Part-1-1
 2,
*Nset, nset=Set-6, instance=Part-2-1
 1,
*Nset, nset=Set-7, instance=Part-2-1
 2,
*Nset, nset=Set-8, instance=Part-2-1
 2,
*Nset, nset=Set-9, instance=Part-1-1
 1,
*Nset, nset=Set-10, instance=Part-1-1
 2,
*Nset, nset=Set-11, instance=Part-2-1
 1,
*Nset, nset=Set-12, instance=Part-2-1
 2,
*Spring, elset=Springs/Dashpots-1-spring

1e+10
*Dashpot, elset=Springs/Dashpots-1-dashpot, nonlinear

-0.001,-10
0.001,10
0.002,20
0.003,30
0.004,40
0.004,1000
*Element, type=SpringA, elset=Springs/Dashpots-1-spring
1, Part-1-1.2, Part-2-1.1
*Element, type=DashpotA, elset=Springs/Dashpots-1-dashpot
2, Part-1-1.2, Part-2-1.1
*End Assembly
** 
** MATERIALS
** 
*Material, name=Material-1
*Density
7800.,
*Elastic
 2e+11, 0.3
** ----------------------------------------------------------------
** 
** STEP: Step-1
** 
*Step, name=Step-1, nlgeom=NO
*Dynamic
1.,1.,1e-05
** 
** BOUNDARY CONDITIONS
** 
** Name: BC-1 Type: Symmetry/Antisymmetry/Encastre
*Boundary
Set-9, ENCASTRE
** Name: BC-2 Type: Displacement/Rotation
*Boundary
Set-10, 2, 2
** Name: BC-3 Type: Displacement/Rotation
*Boundary
Set-11, 2, 2
** Name: BC-4 Type: Displacement/Rotation
*Boundary
Set-12, 2, 2
Set-12, 3, 3
** 
** LOADS
** 
** Name: Load-1   Type: Concentrated force
*Cload
Set-8, 1, -10.
** 
** OUTPUT REQUESTS
** 
*Restart, write, frequency=0
** 
** FIELD OUTPUT: F-Output-1
** 
*Output, field, variable=PRESELECT
** 
** HISTORY OUTPUT: H-Output-1
** 
*Output, history, variable=PRESELECT
*End Step

 

[TEIF-RO]

I went into the manual but, This code was useful as well. Its showed me how to edit an imput file by inserting nonlinear damper
Thanks a lot!!!

 

[TEIF-RO]

@Erik Panos Kostson (Structural)
Just to have the full understanding of the following lines concerning nonlinear damper

*Dashpot, elset=Springs/Dashpots-1-dashpot, nonlinear

-0.001,-10
0.001,10
0.002,20
0.003,30
0.004,40
0.004,1000
Is the first COLUMN force? if yes whats the unit(F)?
Is the second column a relative velocity (Vr)? IF YES WHATS THE UNIT
Thanks for your answer

 

[Erik Panos Kostson]

If we look in the manual (dashpot), the first value is force and the other relative velocity (this is then repeated as needed)
thus
*Dashpot
Force,rel. vel.
Force,rel. vel
...
...

The units are what ever units you deiced to work with since it is not units aware say like Strand7 where we can choose and change units wherever needed.
For your info I always use SI units so m, s, kg, N, Pa,..... (so here velocity is in m/s, and force is in N)