Ultrasonic Guided Waves-Based Monitoring of Rail Head: Laboratory and Field Tests

Figure 5

Test 1. Feature-based unidimensional damage index as a function of the acquisition number. The max amplitude (x), crest factor (o), peak-to-peak (□), and the RMS (◊) of the wavelet coefficient vector are plotted for the (a) high frequency components and (b) low frequency components of the time waveforms acquired with the central pair transducers, and for the (c) high frequency components and (d) low frequency components of the time waveforms acquired with the gage side transducers.

(a)

(b)

(c)

(d)