Ratcheting damage evaluation based on critically refracted longitudinal wave combined with recurrence quantification analysis

Abstract

Excessive accumulation of irreversible plastic strain in ratcheting poses a highly urgent need in early-stage damage evaluation. A strategy integrating critically refracted longitudinal (LCR) wave with recurrence quantification analysis (RQA) is proposed for iron. The signals at different damage stages are reconstructed in multidimensional phase space, and three features, recurrence rate RR, determinism DET, and entropy ENTR, are extracted. With increasing ratcheting cycle, the normalized ENTR difference, ENTRdif, exhibits an obvious increase within ∼1 % life followed by a stabilization trend, while the normalized RR difference, RRdif, fluctuates after an initial rapid rise. Both features show higher sensitivity to the amplitude-based indexes in the LCR wave and pulse-echo methods. The ultrasonic response mechanism is discussed with the rearrangement and mobility of dislocations confirmed by microstructural observation.