Carbon nanotube networks as a strain indicator and failure predictor in polymer matrix composites subjecting to static and dynamic loads

In this work, multiwall carbon nanotubes (MWCNTs) have been used to form a network of sensors to predict the failure region and to monitor the degradation of mechanical properties in laminated composites subjected to tensile and cyclic fatigue loadings. This is achieved by measuring the electrical resistivity change in the semi-conductive MWCNT-fiber glass-epoxy polymer matrix composites. By partitioning the tensile samples with electrically conductive probes, it has been shown that with increasing tensile load, different resistivity changes are detected in different regions and failure happens in the part in which higher resistivity change was detected. In cyclic loading, in which the maximum load is higher than the elastic limit of the laminate, a sharp increase in resistivity occurs within the first several cycles. There is also a change in resistivity during long term cyclic loading which gives this technique a good potential to monitor strength degradation during fatigue.