Localization of Transversal Cracks in Sandwich Beams and Evaluation of Their Severity

Table 1

Measured natural frequencies and corresponding shifts for the analyzed beam.

Mode i	Natural frequency 𝑓𝑖		Relative frequency shift Δ𝑓^∗𝑖		Damage location index Φ𝑖
	Undamaged [Hz]	Damaged [Hz]	Percentage [%]	Normalized [---]	𝜙𝑖^′′ (0.285) [---]	Normalized [---]
1	15.42	13.782	10.62257	0.827801	0.3815	0.765766
2	94.65	93.048	1.692552	0.131898	0.0721	0.220433
3	261.39	231.114	11.58269	0.902622	0.4107	0.947873
4	498.45	478.91	3.92015	0.305492	0.3913	0.346499
5	803.61	793.584	1.24762	0.097225	0.0531	0.111715
6	1163.13	1013.874	12.83227	1	0.4552	1