Open Circuit Resonant (SansEC) Sensor for Composite Damage Detection and Diagnosis in Aircraft Lightning Environments

Abstract

Composite materials are increasingly used in modern aircraft for reducing weight, improving fuel efficiency, and enhancing the overall design, performance, and manufacturability of airborne vehicles. Materials such as fiberglass reinforced composites (FRC) and carbon-fiber-reinforced polymers (CFRP) are being used to great advantage in airframes, wings, engine nacelles, turbine blades, fairings, fuselage and empennage structures, control surfaces and coverings. However, the potential damage from the direct and indirect effects of lightning strikes is of increased concern to aircraft designers and operators. When a lightning strike occurs, the points of attachment and detachment on the aircraft surface must be found by visual inspection, and then assessed for damage by maintenance personnel to ensure continued safe flight operations. In this paper, a new method and system for aircraft in-situ damage detection and diagnosis are presented = distance vector t = time δ = skin depth µ, µ r = permeability and relative permeability σ = conductivity ω = angular frequency of the signal

Design, fabrication, and validation of passive wireless resonant sensors for NDT/SHM

“…As for the eddy currents on the underlying conductive layer, the magnetic field, can penetrate as seen before, only a limited distance, that could be evaluated through the penetration depth. As reported in [9] the carbon composite for aerospace application present a penetration depth ≈ 1 at frequency of 10MHz. The parallel resistance is related to the insulating layer underneath the sensor, and is far less than that of the series resistance.…”

“…While the wireless systems, using an external loop probe, is more suitable for ground inspection, acting as an NDE sensor. Another great advantage of the sensor presented in this work is the ability to monitor both conductive and non-conductive structure, one of the main challenges commonly encountered for resonant circuit [9,10]. The resonant sensor acting as an inductor with a single conductive trace, if damaged, could continue to work [11].…”

Flexible smart sensing skin for “Fly-by-Feel” morphing aircraft

“…When the structure is damaged by impact, in the damage position, the contact resistance between the copper layer and resistance layer will change. A flexible Sans Electric Connection (SansEC) sensor array was developed for in-situ damage detection and diagnostics in metallic or composite airfoil structures (Figure 15(b)) [222]. A single SansEC sensor is an open-circuit self-resonating coil that has unique electromagnetic characteristics consisting of a response frequency, amplitude, bandwidth, and phase [223].…”