Damage visualization of a cylindrical CFRP lattice-skin structure based on a pulse-echo ultrasonic propagation imager

Abstract

Recently, composite lattice structures are attracting significant attention owing to their high specific stiffness and specific strength and are mainly used in aerospace applications. However, the composite lattice structure also exhibits damage occurrence probability during operation as well as defects in the filament winding manufacturing process. Thus a non-destructive evaluation (NDE) technique for defect and damage evaluation is essential although its complexity is not desirable, especially with respect to in-situ NDE. In this study, we propose a pulse-echo ultrasonic propagation imaging (PE UPI) system for in-situ NDE of cylindrical composite lattice-skin specimen and develop a VTWAM (Variable time window amplitude mapping)-based curvature-compensating algorithm that eliminates the curved surface effect of the PE UPI system. As a result of the actual application to a damaged lattice cylindrical specimen, the damage position, size, and shape are clearly visualized by effectively suppressing the curved surface effect in the inspection region via the VTWAM-based curvature-compensating algorithm. We demonstrate the capability of the linear scan PE UPI to inspect a curved and complex lattice-skin structure with a curved surface compensation algorithm and propose the same as a tool for in-situ health management of composite lattice structures for manufacturing to in-service stages.