Finalist EPFL doctorate Award 2010 - Kirkby Eva
© 2010 EPFL
Eva Kirkby's scientific work is (according to the opinion of the jury) ranking among the best 3 % PhD theses awarded by EPFL in 2009. Thesis EPFL, no 4409 (2009). Dirs.: Prof. J.-A. E. Månson and Prof. V. Michaud.
A novel self-healing composite.
This thesis describes the development of a smart composite that senses its own damage and self-heals. The concept is to embed three components into a fibre-reinforced composite: (i) microcapsules containing a liquid healing agent, together with a solid catalyst in the matrix, (ii) optical fibre Bragg grating (FBG) strain sensors and (iii) woven shape memory alloy (SMA) wire actuators. An impact causes a crack to propagate at the damage site, rupturing the microcapsules in its path. This releases the liquid healing agent into the crack, where it comes into contact with the catalyst and begins to polymerise. The strain shock pulse radiating out from the impact site is detected by a sparse array of FBG sensors, which determine the impact location by time-of-flight. With this information, the SMA wires in the impact region are thermally activated using resistive heating, causing them to contract and exert a compressive force, closing the crack. The SMA wires then remain activated during the polymerisation period of the healing agent, after which the crack is healed.