Structural health monitoring using carbon nanotube/epoxy composites and strain-field pattern recognition

Structural Health Monitoring (SHM) aims to reduce costs and uncertainties in maintenance of aero-structures and wind turbines blades by using smart sensors. In this work, a Carbon Nanotube (CNT)/epoxy nanocomposite patch was developed for SHM based on strain field pattern recognition techniques in engineering structures. This relies on the piezoresistive capabilities of CNT nanocomposites and on the fact that damage occurrence produces changes in the strain field that can be detected by means of pattern recognition. Experimental tests were carried out by bonding the patch to an aluminum I-beam subjected to different load magnitudes in three-point bending. Resistance measurements were acquired from the patch using a multiplexed impedance tester in order to obtain 64 measurements that are correlated to strains in different directions. Then, the same experimental tests were carried out after inducing an artificial damage. The preliminary results showed that standardization needs to be performed to decouple changes due to the load magnitude from those produced by damage occurrence. In addition, slight changes in the strain field were noted in the standardized data for the damage condition. Future work will consist of implementing pattern recognition techniques to automatically detect such changes associated with damage occurrence and validate the methodology with different kind of damages.