A surface acoustic wave technique for monitoring the growth behavior of small surface fatigue cracks

A Time-Resolved Line-Focus Acoustic Microscopy Technique for Surface-Breaking Crack Depth Determination

“…6( d) can be obtained and is ready for the application of Eqns. (7) , (8) and (5). The determined TR, RR and TR/ RR as a function of normalized crack depth for a water-filled crack are shown in Figs.…”

“…Rayleigh wave reflection and transmission by a surface-breaking crack has earlier been studied using contact transducers. Various calibration techniques, such as a parallel reference specimen [3], preliminary calibration on a flaw-free specimen [4] and the use of calculated calibration coefficients [5], have been developed to account for the coupling between the transducer and the specimen. A more satisfactory self-calibrating technique, which is independent of the coupling between the transducer and the specimen, has been proposed by Achenbach et al [6].…”

Ultrasonic Reflection by a Planar Distribution of Surface Breaking Cracks

“…Rayleigh waves can be used to measure changes in depth of cracks beneath the surface in advanced engineering materials [1][2][3]. Recently, the crack growth behavior and the crack length distribution of a distribution of surface breaking fatigue cracks have been experimentally studied [4], and a simulation technique for the crack length distribution has been proposed.…”

Self-Calibrating Ultrasonic Technique for R/T and T/R Measurements

“…In this paper we consider the generation and detection of surface waves by contact transducers. Various experimental studies using contact transducer have been presented in [4]- [7]. A major problem in the experimental work has been the uncoupling of the measured results from the response functions of the contact transducers, including the coupling between the transducers and specimen.…”

“…A major problem in the experimental work has been the uncoupling of the measured results from the response functions of the contact transducers, including the coupling between the transducers and specimen. To account for the coupling between transducers and specimen, various calibration procedures have been employed, such as a parallel reference specimen [5], preliminary calibration on a flaw-free specimen [6] and the use of calculated calibration coefficients [7].…”