An experimental study was conducted to investigate the presence of, and assess the quantitative impact of nonlinear propagation effects of water on ultrasonic pulses generated by 5 MHz transducers of the type used in industrial ultrasonic nondestructive evaluation (NDE). Emphasis was placed on ultrasonic instrumentation and configurations which are representative of those widely-used in the aerospace and metals industries. First, a brief description of ultrasonic NDE and some background on medical and industrial ultrasonic NDE applications, along with rationale for a study of this type, is presented. Next, the extensive theoretical and experimental work done by the medical community in the area of nonlinear ultrasound propagation is summarized. The manifestations of nonlinear propagation are described. The experimental configuration used in this study, its extensive characterization, and the methodology of pulse spectral analysis as used here are also described. Experimental data are presented which show that nonlinear propagation effects, due solely to the water coupling medium, are present for typical industrial ultrasonic NDE testing configurations, and why these effects are not normally observed in practice. Also presented are experimental data used to assess the quantitative impact of these effects in commonly-used industrial ultrasonic measurements, especially with respect to interpretation and measurement uncertainty. Nonlinear propagation effects for these testing configurations were unequivocally detected, and found to have only a small quantitative impact.
Citation: University Microfilms International (U.M.I.)
Pub Type: Others
Hydrophone, Nondestructive evaluation, Ultrasonics