Direct write sensors for health management of composite aerostructures

Direct Write Thermal Spray was employed to fabricate strain gages and thermocouples directly onto composite laminates to assess their performance characteristics and survivability in representative environments. Strain gages exhibited a gage factor of ∼1.3, with a consistent peak-to-peak response ideal for dynamic strain monitoring. Direct Write Type K thermocouples effectively monitored temperature during successive thermal cycling, although the Seebeck was ∼8% lower when compared to wire Type K thermocouples. Nevertheless, Direct Write sensors outlasted commercial reference sensors in accelerated degradation testing, thus providing both the manufacturability and requisite survivability for condition and health monitoring of aerospace composites.