Two-Node Link - Damping

[GianniPellegrini]

Hello everyone,
I could have done a few tests before making this question, but I'll have a try:
I am modelling a pile with lateral springs using the two-node link element. I created an uniaxial Elastic material associated with the link.
I applied the Rayleigh damping to the model excluding (default option) the links.
Now, I would like to apply a stiffness-proportional damping to each spring.
I thought about two possible solutions:
1) using ETA factor of the uniaxial elastic material
2) defining a region for the link elements only

If I'd like to apply a stiffness proportional coefficient of 0.01,
should I
1) using ETA = 0.01 * tangentE in the Unixial Material, or
2) using alphaM=0, betaK=0, betaKinit=0.01, betaKcomm=0.

Considering that I am still applying the rayleight damping for the remaining part of the model, are 1) and 2) equivalent?

Thank you
Gianni

[mhscott]

I think you should test this out for yourself.

[GianniPellegrini]

I think you should test this out for yourself.

Thank you for your comment.
Yes, I tried but the results are different.

If I am not making a theoretical mistake, I think the problem is because the two-node link does not consider the damping from the "region command".
Without opting for '-doRaylegh", it seems the damping of the springs is zero regardless of the use of the region command.

On the other hand, if I opt for '-doRaylegh" the damping seems calculated according to the parameters of the global rayleigh object and not from the region one.

I was thinking that the damping from region (local) should overwrite the damping parameters from the rayleigh element (global). This does not seem the case.
Not sure if this is true for all the elements or just for the joints.