An imaging method for the covered damage region of strand wire based on dual time reversal using piezoceramic transducers

Abstract

According to damage detection of strand wire structures covered by anchor clip, an ultrasonic guided wave damage imaging detection method based on dual time reversal was suggested. It utilizes the characteristic of the guided waves traversing the whole tested region and the characteristic of time reversal making the signals gathered in the source at the same time. First, a modulation signal is excited by piezoceramic transducers at one end of the detected region of the strand and the reflection signals and the transmission signals are acquired. Then, a non-defective finite element simulation model corresponding to the detected strand is established. The extracted reflection and transmission damage signals can be imported respectively into the non-defective simulation model after time reversal processing to re-spread. The propagation of the reversal signal in the simulation model causes the model nodes to produce a displacement. These displacements can be extracted separately and calculated by dual time reversal operation, which means multiplying the nodes of the same coordinates at each of the two results. Finally, the result of the focusing operation is accumulated at all times and the damage region can be calculated. The focus results are presented by the point cloud. Experimental results show that the difficulties of traditional time focusing in strand wire structures can be overcome, and the damage region can be imaged preliminarily with a small relative error.