Can't really tell from that, if it was a transfer function then the dotted line is the estimated accelerance (inverse of mass) if that is the driving point response. There's a lot of ifs buts and whens in that statement.
Obviously the pair of modes at 150 Hz are the ones of interest, probably some subsystem is acting as a vibration absorber. But you need proper data first (transfer function, with phase) not response rubbish, and more than one accelerometer.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
Yes, unless you know the excitation was a constant pk-pk force. If it was then you model the modes using any of the known techniques and that'll tell you which has the biggest modal mass, /at that excitation point/. It's the first one in this case obviously at 150 Hz, and it looks as though you might have a split peak due to a subsystem acting as a harmonic damper. That's probably an unwise amount of info to extract from an amplitude plot, a hammer test survey is much better for establishing modal mass (of which I've seen at least 4 definitions).
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
