Table 7: The damping ratios identified by using SSI method from experimental specimens.

Undamaged22.2% delaminated51.9% delaminated74.1% delaminated

From random
responses
Frequency (Hz)31.6126.8327.5624.31
(%) 1.051.341.681.71
From impact
responses
Frequency (Hz)31.6226.8727.449.15
(%) 1.251.461.321.43