Self-Induced Hysteresis for Nonlinear Acoustic Waves in Cracked Material

Abstract

A new phenomenon of self-induced hysteresis has been observed in the interaction of bulk acoustic waves with a cracked solid. It consists in a hysteretic behavior of material nonlinearity as a function of the incident pump wave amplitude. Hysteresis manifests itself in the self-action of the monochromatic pump wave and in the excitation of its superharmonics and of its subharmonics. The proposed theoretical models attribute the phenomenon to hysteresis in transition of the acoustically forced oscillation of cracks from a nonclapping regime to a regime of clapping contacts.

Non-destructive testing techniques based on nonlinear methods for assessment of debonding in single lap joints

“…In general, nonlinear oscillation systems exhibit a greater variety of phenomena which result in the nonlinear spectrum transforms to subharmonics and chaos [10]. The acoustic subharmonics produced by the crack vibrations were observed [11,12] and a subsequent threshold transition to chaotic dynamics for the higher excitations was shown [12,13]. These results indicate the correlation between an integral damage induced and the subharmonic (and/or "acoustic noise") level while they do not allow one to locate the flaws.…”

Measurement of dissolved hydrogen distributions after ultrasonic peening of heat-affected zone of welded joint

“…Nonetheless, there is still a problem, since material deformation due to high-frequency ultrasonic treatment can lead to a variety of contradicting phenomena, which are (i) acoustic softening [3], (ii) acoustic hardening [4], (iii) acoustic heating [5], etc. Researchers suggest various interpretations of the strong influence caused by this small effect.…”

Evaluation of closed cracks by analysis of subharmonic ultrasound

“…In this respect, subharmonics shown in Fig. 1 (e) [4,5] has much higher S/N ratio than superharmonics and potentially useful for accurate sizing of partially closed cracks. Based on the theory of nonlinear contact vibration in atomic force microscopy [6,7], we developed a theory for subharmonic generation.…”

“…This has been a fundamental problem in ultrasonic testing (UT) of cracks which many researchers have tried to solve without complete success. To solve this problem, detection of superharmonic signals generated at cracks by the nonlinear effect of large amplitude ultrasound ( Fig.1(d)), has been expected as the most promising approach [3][4][5]. However, the signal-to-noise (S/N) ratio of superharmonics is not very high, because it is generated also in piezoelectric transducers and liquid media, which becomes background noise.…”

“…From these results, it is shown that the subharmonic generation requires time delay due either to inertia (high ω ) or viscosity (large γ ). Also it is noted that there is a hysteresis of subharmonic amplitude [5] since the waveform for ω =1 is asymmetric. In usual testing, we propose to use constant amplitude tone burst with a few carriers, rather than an amplitude-modulated signal.…”