TRENDS OF NONDESTRUCTIVE SENSING OF INTERFACIAL DAMAGE AND REINFORCING EFFECT OF FIBER/MATRIX NANOCOMPOSITES USING ELECTRO-MICROMECHANICAL TECHNIQUES

Trends of unique electro-micromechanical techniques have been explained and used as an efficient nondestructive evaluation (NDE) method for sensing and determination of micro-damage at the filler/epoxy interface in nanocomposites. Prior research activities have developed NDE methods to identify and avoid structural damage in fiber/matrix nanocomposites. Furthermore, such detection methods have been used in place of expensive external sensors to detect damage in polymer matrix nanocomposites. Up to now, micro-mechanical and electrical resistance measurement methods have been used to sense the damage and strain induced by stresses or shape changes in conductive polymer nanocomposite materials. This “Self-sensing” method has also been used to evaluate interfacial damage in fiber reinforced polymer matrix nanocomposites. The advantages of this new NDE method include better stability, lower cost, and relative simplicity. Electro-micromechanical technique can be applied for carbon nanotube (CNT)/epoxy composites using four-point probe method with their contents. The fracture of carbon fiber is detected by nondestructive acoustic emission (AE) relating to electrical resistivity under double matrix composites (DMC) test. The damage sensitivity of fiber fracture, matrix deformation and fiber tension for CNT/epoxy composites can increase with CNT volume fraction. Reinforcing effect of CNT addition obtained from mechanical properties and apparent modulus measurements can be identified. For the concept of nondestructive evaluation, damage sensitivity and reinforcing effect of carbon nanocomposites can be obtained from the electrical resistivity measurement with AE.