Design of Self-healing Materials for the Integration of Structural Health Monitoring (SHM2)

Abstract

Integration of the complementary fields of structural health monitoring in self-healing materials (SHM2) has the potential to transform the traditional engineering concepts of fail safe and damaged tolerant design. Structural health monitoring seeks to embed and automate sensing capabilities within structures to determine their state and to detect degradation or damage. Once degradation or damage is detected, additional decisions and potential action are required. Restricting operational envelopes can prevent further damage accumulation or catastrophic failure, alternatively, repairs can be performed to correct the degradation. Typical repair requires active involvement of personnel and potentially system down time. Self-healing materials seek to avoid maintenance needs and down time through the creation of structures and materials with an imbued capability to repair damage. Together SHM2 has the potential to create a closed loop where damage is detected using embedded sensors and automated analysis that can then initiate self-healing. The highly structured and controlled nature of self-healing materials presents an opportunity to design structures that additionally support health monitoring capabilities. This paper presents recent research and results informing the design of shape memory alloy (SMA) fibre reinforced metal matrix composites (MMCs) to optimize self-healing capabilities and structural health monitoring (SHM2). Fibre pull tests were performed to analyse the strength of the interface between the SMA fibres and matrix allowing for sizing to complement both composite design and healing capabilities. Analysis was performed to understand complex failure mechanisms occurring at the interface between detwinning shape memory alloys and the metal matrix. And novel composite design was explored to support both the self-healing and damage detection capabilities of the material structure. The combination of experimental results and analyses can be used to guide the microstructural design to materials to support both structural health monitoring and self-healing.