Giant magnetoresistance scanning of magnetic self-sensing composites

Abstract

Fiber-reinforced composite materials possess excellent strength-to-weight ratios, making them especially useful in industries like aerospace where weight is critical. However, the brittle nature of fiber-reinforced composites allows damage to propagate quickly. Additionally, damage to composite materials is typically difficult to detect. This combination of damage sensitivity and challenging damage detection can lead to conservative designs that are heavier and costlier than necessary. In this study, a technique for characterizing damage in a unique self-sensing composite material is described. This is accomplished using magnetic particles autonomically formed in situ to highlight internal damage. A scanner based on GMR sensors is used to measure the location and size of damage, with an accuracy of up to 91% when compared to C-scan. This non-contact method provides several benefits, including requiring only one side of access to the material, good scanning speeds, and low cost. Here, the performance of this scanning system is characterized in detail. The NDE effectiveness is investigated with studies of scan resolution, scan accuracy, minimum detectable size, maximum detectable depth, and the effect of flaw orientation and particle concentration. Additionally, the spatial resolution and correlation of the response to the actual damage size compared to C-scan ultrasound will be discussed.