Practical Solutions for Embedding Fiber Optic Strain Sensors in Composites

A multidisciplinary team performing under the Aircraft and Aircrew Protection (A&AP) project between Sikorsky and the US Army Combat Capabilities Development Command Aviation & Missile Center (CCDC AvMC) successfully demonstrated the assembly of a full-scale fiber-optic-instrumented composite aircraft structure assembly. Through a building-block progression from test coupons to sub-scale to full-scale assemblies, the team developed practical strategies to maximize fiber optic survival rate and utility. Ultimately, the team defined and implemented five key elements to enable successful fiber optic strain sensor embedment in structural composites: thoughtful arrangement of the fiber optic network, controlled placement of strain sensors and excess fiber in the laminate, accommodation of minimum fiber optic bend radii, encapsulation of the fiber at the egress point from the composite laminate, and protection of the connector termination. These elements allow for a robust strain-sensing network that can be utilized for damage detection and advanced structural health monitoring.