Damage Identification by Using a Self-Synchronizing Multipoint Laser Doppler Vibrometer

Table 2

Relative crack depth calculated by (7) and (8).

	Cracked beam ( = 0.4)	Cracked beam ( = 0.5)
α (actual)	0.4	0.4
First frequency change ratio	0.0218	0.039
α calculated by (7)	0.353	0.367
Relative error	11.75%	8.25%
Second frequency change ratio	0.0142	0.0458
α calculated by (8)	0.382	0.333
Relative error	4.5%	16.75%