Future trends in health monitoring of materials

New nanocomposites materials based on electrically conductive fillers with high aspect ratio (whiskers) dispersed in a film forming polymeric matrix were prepared with various amount of fillers. The transport properties are directly linked with the macroscopic mechanical strain on the composites during uniaxial tensile test and with time under relaxation, meaning that the method is suitable for monitoring microstructural evolution of such composites. This evolution has been related to microstructural evolution of the network formed by the fillers (whiskers) when the material is stretched. The decrease of the conductivity real part indicates the breaking of the percolating network, while the imaginary part gives information on the possible “spatial correlation” of the damage events. The relationships between microstructure and macroscopic properties were simulated with the help of a RC model for the electrical properties and with finite element technique for the mechanical properties. The use of such material as sensor coated on a material to be monitored is discussed. Strain, strain rate and failure can be easily characterized through the electrical properties.