Enhancing the Strain Sensitivity of Carbon Nanotube-Polymer Thin Films For Damage Detection and Structural Monitoring

Today the rapid growth of fiber-reinforced polymer (FRP) applications in the automotive and aerospace industry has motivated many researches to perform life-cycle analyses of FRP structures. While its strength-to-weight ratio outperforms conventional metals, FRP is inherently heterogeneous and experiences complex failure modes, thus making them challenging for structural analysis and design. Assessing structural conditions such as employing structural health monitoring (SHM) sensors to observe its in-situ behavior may help prevent large-scale structural failure while simultaneously providing a chronological account of structural behavior due to known damage occurrences. Among the various SHM techniques, carbon nanotube (CNT)-polymer thin films can be rapidly applied onto FRP surfaces, or possibly embedded in the material, for damage detection. In this study, the strain sensitivity of embedded CNT-polymer thin film strain sensors was improved by nearly three times. The goal was to use these sensors to capture mild structural deformation by measuring induced strains in the structure. Furthermore, the geometrical influence of a thin film on its electrical response was investigated. Both results provided guidance as to how these sensors could be eventually applied for real-world FRP structures.