Dear Daniel,
Your overall approach sounds reasonable. Just a few comments:
- Your hydro_k and hydro_m matrices seem to match those from your WAMIT output in the attachments. However, the WAMIT output is nondimensional whereas BModes is expecting the data to be dimensional. See the following forum post for information on how to dimensionalize the WAMIT output: WAMIT - #4 by Jason.Jonkman.
- For your body weight term, it looks like your z is positive valued i.e. the center of mass is above MSL; is that correct?
- I would expect the unstretched length of the tendons of a TLP to have a significant effect on the tendon tensions/stiffness and resulting natural frequencies.
Best regards,