TDR Structural Health Monitoring

Material Sensing & Instrumentation (MSI)

MSI Time-Domain-Reflectometry (TDR) Structural-Health Monitoring probes the structural health of a composite part by propagating a fast electrical pulse along a distributed linear sensor which has been fabricated directly in the laminate. The sensor is formed from the native graphite fibers already used in composite manufacture, and constitutes zero defect. Fibers are patterned into a microwave waveguide geometry, or transmission line, and interrogated by a rapid pulse as shown below. Structural faults along the line cause distortions in waveguide geometry, producing reflected pulses similar to radar. Cracking, delamination, disbonds, moisture penetration, marcelling, and strain are all detected by propagation delay, for sensor lengths up to several meters.