A material system with integrated fault diagnosis and feedback controlled self-healing

Two significant drawbacks of current self-healing materials are that they are: (1) Passive and as such do not guarantee a match between the healing and damage rate; (2) Not monitored during and after healing, so that the performance of the healed material is not known without retrospective offline testing. As a consequence their application is currently limited in some sectors, such as the aerospace sector where high performance needs to be guaranteed within strict guidelines. This article proposes the first active self-healing material that integrates with control and fault diagnosis to provide a system with a desired healing response. A fault diagnosis algorithm using supervised regression is used to estimate the measure of damage. Then based on this estimate, adaptive feedback control is used to ensure a match between the healing response and the damage rate, while taking into account the nonlinear system dynamics and uncertainty. The system is demonstrated in simulation using a self-healing material based on piezoelectricity and electrolysis. This shows the ability of the integrated subsystems to tackle these two significant drawbacks of most current self-healing systems and will benefit applications with strict performance requirements, or systems operating under harsh conditions or that are remotely accessed.