# DAMPING should be preceded by a \*MATERIAL card
**URL:** https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674
**Category:** Uncategorized
**Created:** [May 23, 2023, 1:34pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674 "2023-05-23T13:34:40Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Disla](https://calculix.discourse.group/u/Disla)
#### Post date: [May 23, 2023, 1:34pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674/1 "2023-05-23T13:34:40Z")
Hi,
I would like to apply some Rayleigh damping to some spring elements with a mass attached to one of the nodes of each one.
¿Is it possible.? Ccx is complaining.
\*ERROR reading \*DAMPING: \*DAMPING should be preceded by a \*MATERIAL card \*WARNING in calinput: no elastic constants were assigned to material MASS in a (thermo)mechanical calculation
\*ERROR in calinput: at least one fatal error message while reading the input deck: CalculiX stops.
This is a simple example.
```auto
*NODE
1,0,0,0
2,0,0,0.1
*ELEMENT,TYPE=SPRINGA
1,1,2
*ELEMENT,TYPE=MASS
2,2
*ELSET,ELSET=Default
1
*ELSET,ELSET=Mass_1
2
*SPRING,ELSET=Default
1.764000000000E+003
*BOUNDARY
1,1,,0
1,2,,0
1,3,,0
2,1,,0
2,2,,0
*MASS,ELSET=Mass_1
1
*INITIAL CONDITIONS,TYPE=DISPLACEMENT
2,1,0
2,2,0
2,3,0.05
*DAMPING,ALPHA=0.0062,BETA=0.0004
*STEP,INC=110,AMPLITUDE=STEP
*DYNAMIC
0.01,1,0,0.01
*NODE FILE,GLOBAL=YES
U
*EL FILE
S,NOE
*END STEP
```
¿What are those elastic constants I need to assign to the mass?
---
### Author:  [@Calc\_em](https://calculix.discourse.group/u/Calc_em)
#### Post date: [May 23, 2023, 1:51pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674/2 "2023-05-23T13:51:22Z")
According to the documentation, this type of damping doesn’t have to be placed under \*MATERIAL:
> Keyword type: model definition, **if structural damping: material**
But in practice, it seems to be necessary for some reason. Maybe you could just use the dashpot element instead. It would fit your spring-mass system.
---
### Author:  [@Disla](https://calculix.discourse.group/u/Disla)
#### Post date: [May 23, 2023, 2:26pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674/3 "2023-05-23T14:26:30Z")
Hi Calc\_em and Thanks.
I’m interested in Rayleigh damping effect on my model, so I need to be able to play with those coefficients.
Note: I liked your last Prepomax YouTube video.
---
### Author:  [@Calc\_em](https://calculix.discourse.group/u/Calc_em)
#### Post date: [May 23, 2023, 2:41pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674/4 "2023-05-23T14:41:44Z")
> [@Disla](#):
>
> I’m interested in Rayleigh damping effect on my model, so I need to be able to play with those coefficients.
Perhaps there’s at least a way to convert Rayleigh damping coefficients to dashpot coefficient. Or you could model the mass as a solid cube and then define material damping.
Only the following damping options are available for \*DYNAMIC analysis:
> - Rayleigh damping by means of the \*DAMPING keyword card underneath a \*MATERIAL card
> - Dashpot damping by defining dashpot elements
> - Contact damping by defining a contact damping constant and, optionally, a tangent fraction using the \*CONTACT DAMPING keyword card
> [@Disla](#):
>
> Note: I liked your last Prepomax YouTube video.
Thanks, it took me a while to finally realize this topic.
---
### Author:  [@JuanP74](https://calculix.discourse.group/u/JuanP74)
#### Post date: [May 23, 2023, 3:24pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674/5 "2023-05-23T15:24:18Z")
Manual p. 421, this is damping for continuum or structural elements, springs I guess you have to use dashpots for damping. alpha multiplies the mass matrix and beta the stiffness matrix to build the damping matrix, so if you want that combination for a 0D element just do the multiplication to create the C for the dashpot associated to same dofs as the spring.
Example:
`*DAMPING,ALPHA=5000.,BETA=2.e-3`
indicates that a damping matrix is created by multiplying the mass matrix
with 5000. and adding it to the stiffness matrix multiplied by 2 · 10−4
Example:
`*DAMPING,STRUCTURAL=0.03`
defines a structural damping value of 0.03 (3 %). **This card must be part of**
**a material description.**
Example files: beamimpdy1, beamimpdy2
---
### Author:  [@Disla](https://calculix.discourse.group/u/Disla)
#### Post date: [May 23, 2023, 8:00pm UTC](https://calculix.discourse.group/t/damping-should-be-preceded-by-a-material-card/1674/6 "2023-05-23T20:00:44Z")
> [@Calc\_em](#):
>
> you could model the mass as a solid cube
Thanks to both of you,
I was preparing the proposal of the cube at the tip and …surprise. If a dumb cube is added to the system the matrix is assembled and the problem is solved with the springs. I am referring to a loose cube. I have yet to see if the result makes sense but it is surprising isn’t it?😂
