Aerospace systems stand to benefit significantly from the advancement of reflexive aerostructure technologies for increased vehicle survivability. Cornerstone Research Group Inc. (CRG) is developing lightweight, healable composite systems for use as primary load-bearing aircraft components. The reflexive system is comprised of piezoelectric structural health monitoring systems, localized thermal activation systems, and lightweight, healable composite structures. The reflexive system is designed to mimic the involuntary human response to damage. Upon impact, the structural health monitoring system will identify the location and magnitude of the damage, sending a signal to a discrete thermal activation control system to resistively heat the shape memory polymer (SMP) matrix composite above activation temperature, resulting in localized shape recovery and healing of the damaged areas. CRG has demonstrated SMP composites that can recover 90 percent of flexural yield stress and modulus after postfailure healing. During the development, CRG has overcome issues of discrete activation, structural health monitoring integration, and healable resin systems. This paper will address the challenges associated with development of a reflexive aerostructure, including integration of structural health monitoring, discrete healing, and healable shape memory resin systems.
Seamless skins for morphing vehicles have been demonstrated as feasible but establishing robust fastening methods for morphing skins is one of the next key challenges. Skin materials previously developed by Cornerstone Research Group and others include high-performance, reinforced elastomeric and shape memory polymer (SMP)-based composites. Recent focus has shifted to improving performance and increasing the technology readiness level of these materials. Cycling of recently demonstrated morphing skins has determined that an abrupt interface between rigid and soft materials leads to localized failure at the interface over time. In this paper, a fundamental understanding between skin material properties and transition zone design are combined with advanced modeling techniques. A thermal gradient methodology is simulated to predict performance benefits. Experimental testing and simulations demonstrated improvement in morphing component performance for a uniaxial case. This work continues to advance development to eliminate fastening as the weak link in morphing skin technology and provides tools for use in morphing structure design.
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