How to obtain damping ratio with Curve Fitting Toolbox

Hi everybody,

I have some experimental data from an oscillating system (time domaine) and I would like to get an approximation of the damping ratio (zeta). I have already try to use the half-power band width method with the vibrationdata Matlab package designed by Tom Irvine. But I would like to double-check the result with another method.

I found several methods in this paper : www.vce.at/sites/default/files/uploads/downloads/2007_damping_estimation.pdf and I would like to try to do the curve fitting method with the Curve Fitting Toolbox of Matlab (R2014b) (2.2.2 Curve fitting in the paper).

It's the first I use this Toolbox with a custom equation, so, I do not really know how to do it with my sample data.

Can anybody help me with this ? I have attached the .txt file sample data to this post.

Cheers