How do i calculate damping ratio using a half power method

I am trying to get damping ratio from a Frequency response plot.

I have used a peakfind to get the peaks and return the natural frequewncies and have plotted the half power line onto my original frf plot but cannot get the band width where the lines intersect. i have tried polyfit and interpl but these are not working.

Thanks

Answer 1

[Nishant Gupta]

You can refer to the following case to calculate the -3 dB intercept and hence can calculate the bandwidth:

https://www.mathworks.com/matlabcentral/answers/338054-bode-plots-viewing-values-at-a-particular-point?s_tid=answers_rc1-1_p1_Topic