Progress Towards Autonomous Structural Health Management

The Autonomous Sustainment Technologies for Rotorcraft Operations-Structures (ASTRO-S) project between U. S. Army Combat Capability Missile Center, Aviation Development Directorate-Eustis (FCDD-AMV-E) and Sikorsky developed and validated a range of technologies to enable reduced airframe maintenance burden, increase operational availability, and provide key enabling technologies relative to Army's transition to the new paradigm of Maintenance Free Operational Periods (MFOP) for the rotorcraft of the future. Methods were developed for autonomous characterization of major damage and residual strength expressed as a Structural Health Index (SHI) for advanced durable and damage tolerant composite aerospace structural assemblies with redundant load paths, enabling targeted inspections and strength-based fly / watch / repair decisions. A number of sensing technologies including fiber-optic strain measurement and piezo-based structural health assessment, along with a number of innovative advanced algorithms that intelligently use changes in monitored structural responses, were implemented in a comprehensive architecture to detect, localize, and assess the severity of structural damage. Extensive testing on full-scale, multiload-path composite structures to assess feasibility and effectiveness of the developed technologies, as well as understand application and transition challenges, has convincingly shown that damage detection, localization, and severity assessment in an autonomous fashion is feasible. Further, it was shown that the concept of a trendable SHI to assess residual strength, is viable, although additional full-scale test cases are needed to further validate and mature the approach. Overall, these key findings affirm suitability of the technical approach and associated algorithms for reducing maintenance burden by triggering rather than scheduling inspections and potentially deferring repairs in high op-tempo environments. These structural health management technologies will be key enablers supporting Army's future rotorcraft when operating in an untethered multi-domain battle space.