Wireless Sensing of Temperature, Strain and Crack Growth in 3D-Printed Metal Structures via Magnetoelastic and Thermomagnetic Inclusions

In this study, we demonstrate the first realization of wireless strain and temperature sensing within 3D-printed metallic structures using standard electromagnetic inspection hardware. This establishes a path toward need-based parts maintenance driven by accurate damage assessments instead of relying on regularly scheduled maintenance teardowns, extending the service intervals of structures operating in harsh environments. To this end, we encapsulate magnetoelastic and thermomagnetic materials inside microtubes and embed the sensing elements during additive manufacturing. Mechanical and thermal stimuli affect the magnetic permeability of the embedded materials, which modulates the impedance of a coil placed on or near the surface of the printed part. We demonstrate strain sensing accurate to +/-27x10-6 over at least a 6x10-4 strain range, and temperature sensing accurate to +/-0.75oC over a 70oC range, both to a 95% confidence interval. We highlight these sensors' capabilities by detecting the onset of plasticity and fatigue-driven crack growth thousands of cycles before critical failure. This extends non-destructive eddy-current damage detection to accurate, real-time strain and temperature monitoring within metallic structures.