Ultrasonic guided wave-based switch rail monitoring using independent component analysis

Abstract

Switch rails are indispensable components of high speed railway systems, which have stringent nondestructive testing requirements owing to the severe operating conditions. In this article, an ultrasonic guided wave method is proposed for defect detection and localization using independent component analysis (ICA). The temperature effect is included in the data matrix by a random selection of the signals measured at different temperatures. A damage index named the average standard Euclidian distance (ASED) is used to evaluate the deviations of the test signals from the baseline signals in the feature space consisting of the independent components for the defect detection. Once the defect existence is found, defect localization is conducted by another ICA-based decomposition of a new data matrix with additional test signals for the same defect. Independent components whose coefficient vectors show a high correlation with the standard step change vector are chosen to construct the ICA-based residual signal. Then the time instance and location of the defect is determined by observing the first very high peak occurring in the residual signals. A detectability index for defect location (DIDL) is proposed. Experimental validations are performed for the defects on the foot and web of a switch rail. The results of the ASED curves clearly indicate the existence of artificial defects, and the ICA-based residual signals show the location of the defects. The proposed method is found to be superior to conventional methods such as simple baseline subtraction and optimal baseline subtraction regarding the DIDL.

Guided wave‐based damage assessment on welded steel I‐beam under ambient temperature variations

“…Among them, the ultrasonic guided wave method has been recognized as one of the efficient nondestructive testing (NDT) approaches to scan long structural members. It has been applied to inspect pipelines, 22,23 cables, 24,25 rails, 26–28 and many other types of structures 29–31 . One of the common NDT strategies using guided waves is called the pulse‐echo method, where the transducer simultaneously works as the actuator and sensor 32 …”

“…Many signal‐processing methods have been proposed to address the temperature variations and other environmental effects 41–43 . However, for the acoustic signals obtained from complex structures such as rails and I‐beams, conventional methods such as the optimal baseline subtraction are not applicable to compensate for the temperature effect 27 . The principal component analysis (PCA) is a statistical method for feature space decomposition 44 .…”

“…One or several ICs containing damage information can be distinguished from the other ICs by user‐defined criteria, e.g. 27,51 …”

Experimental Study of the Guided Wave Directivity Patterns of Thin Removable Magnetostrictive Patches

“…Non-Destructive Testing (NDT) techniques are widely used for the inspection of different structures in numerous industrial applications. Guided Waves (GWs) are among these techniques and they are widely used in different applications such as the inspection of pipes [ 1 , 2 ], rails [ 3 , 4 ] and plates [ 5 , 6 ]. GWs in plates and pipes are complex as they are generally dispersive, although some modes, such as the SH0 mode in a plate and the T(0,1) mode in a pipe, can be non-dispersive.…”

Signal Strength Enhancement of Magnetostrictive Patch Transducers for Guided Wave Inspection by Magnetic Circuit Optimization

“…Guided waves, which are ultrasonic waves restricted by the boundaries of the solid waveguide during propagation [1], have been applied in the inspection of many industrial structures, such as pipes [2,3], rods [4], plates [5][6][7] and rails [8][9][10] with the advantages of long distance, full coverage and low cost [11]. The conversions between the electrical energy and mechanical energy are mainly involved in guide wave inspection, which are accomplished by the transducers as the key parts in the inspection system.…”