Hi Marvin,
I’ve attached a document written by Emmanuel Branlard at NREL that describes how to modify the blade structural properties when changing the reference axis. E.g., you could apply the relationships documented here if the original reference axis is not smooth, and fitting a smooth curve to the reference axis results in offsets of mass and stiffness from the smoothed reference axis. This document also provides guidance for converting HAWC2 blade models to BeamDyn.
BeamDynInput_05_2020.pdf (252 KB)
Regarding the oscillations introduced by the straight blade, I’m not sure. Which mode(s) of the blade are oscillating? Does adding numerical or structural damping reduce the oscillations over time?
Best regards,