Table 6: Modal frequencies identified by PP, FDD, and SSI ( , ) methods from experimental specimens under random excitation.

1st bending 2nd bending1st bending/torsion3rd bending

PP (Hz)31.6068.8884.66165.95
UndamagedFDD (Hz)31.7768.0383.04166.08
SSI (Hz)31.6167.6282.60166.37

PP (Hz)26.6951.0092.07
22.2%
delaminated
FDD (Hz)27.0150.7791.79
SSI (Hz)26.8350.6791.74

PP (Hz)27.6055.9496.79
51.9%
delaminated
FDD (Hz)27.5154.5396.80
SSI (Hz)27.5655.5296.94

PP (Hz)24.4144.6984.38
74.1%
delaminated
FDD (Hz)24.0144.7784.54
SSI (Hz)24.3144.3784.63