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.

Microfluidic Encapsulation of Aqueous Solutions for Use in Magnetic Self‐Sensing Composite Materials

“…All specimens were tested, and then scanned using a magnetic scanner developed in previous work. [ 10 ]…”

“…All specimens were tested, and then scanned using a magnetic scanner developed in previous work. [10] Supporting Information Supporting Information is available from the Wiley Online Library or from the author.…”

“…Accurate detection of the magnetic particles was achieved using a variety of modalities, including visually, thermally, and magnetically via a low-cost magnetic scanner. [10] Here, we present a novel microcapsule-based version of the previously reported NDE system. This damage detection technique has not previously been demonstrated using microcapsules as the delivery method and is distinct from existing NDE methods that focus on color change, [7] fluorescence, [8] or other techniques to produce a visual change in response to outside stimuli.…”

“…The approach described here results in the precipitation of magnetic particles that can potentially be detected without a visual line‐of‐sight. [ 10 ][ 9 ] Each of the two liquid detection agents is sequestered in a separate capsule that are then incorporated into the matrix material when a composite is being fabricated. One microcapsule type contains an aqueous iron chloride solution, and the second type contains an aqueous ammonium hydroxide solution.…”

“…Accurate detection of the magnetic particles was achieved using a variety of modalities, including visually, thermally, and magnetically via a low‐cost magnetic scanner. [ 10 ]…”