Application of a higher order crossing feature to non-destructive evaluation: a sample demonstration of sensitivity to the condition of adhesive joints: Ultrasonics, Vol. 29, No. 5, pp. 355–365 (Sep. 1991)

Abstract

Abstract In this study, the essential elements of the higher order crossing (HOC) method for signal analysis are outlined. The method is relatively simple to apply, has remarkable data and information compression capabilities, preserves the spectral parameters of the signals and has good feature discrimination abilities. These properties make the HOC method attractive for application to non-destructive evaluation (NDE) analyses whenever the inspection techniques involve the accumulation and processing of time domain signals. As a sample case, features of the HOC method were applied in this work to the analysis of experimental ultrasonic echo signals obtained from metal-to-metal and composite adhesive joint specimens. The HOC features revealed sensitivity to both the adhesive and cohesive properties of the joints. The sensitivity, which was verified by means of statistical tests, enabled the classification of the specimens according to their bond characteristics.