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Passive self repairing and active self sensing in multifunctional polymer composites

The goal of the research since the early 1990s has been to develop self-repairing and self sensing composites. Our revolutionary approach involves the autonomous release of repair chemicals from within the composite matrix itself and the active sensing to assess that action utilizing the same tube structure. The repair agents are contained in hollow, structural fibers that are embedded within the matrix. Under stress, the composite senses external environmental factors and reacts by releasing the repair agents from within the hollow vessels. This passive autonomous response occurs wherever and whenever cracking, debonding or other matrix damage transpires. Superior performance over the life of the composite is achieved through this self-repairing mechanism. The active sensing measures volume of voided repair chemical and location of voiding reveals the location and amount of damage to the laminate. This health monitoring of composites is important for their widespread use in life safety applications such as structures. The focus of the research being the implementation of active sensors and passive actuators which by using the same structure of glass tubes provide large area coverage without adding much parasitic weight. The development is a novel, voiding based sensor for damage detection with composite structures. This consists of a inspection guide produced from glass reinforcing fibers which release repair chemical when damaged.. The sensor was shown to be sensitive to very low impact energies, but also capable of revealing more extensive damage caused by high energy impacts. This unique combination of active sensing and passive repair serves as an example of combination for autonomous systems that can consist of various approaches in one integrated system.