Radial strain-induced resistivity variations in fiber-reinforced nanocomposites: A concentric cylindrical analytical model

The growing use of fiber-reinforced composites in aerospace, automotive, and civil engineering necessitates advanced non-destructive monitoring methods, as these materials often exhibit complex and undetectable failure modes. Self-sensing composites incorporating conductive nanofillers such as carbon nanotubes (CNTs) and carbon nanofibers (CNFs) enable real-time monitoring through strain- or damage-induced changes in electrical resistivity. However, accurate mechanical interpretation of these electrical observations requires piezoresistivity models that extend beyond micro- to nanoscale behavior and explicitly account for continuous fiber reinforcement at the structural scale. This paper presents an analytical model for predicting piezoresistive behavior in continuous fiber-reinforced nanocomposites subjected to radial deformation. Building on prior axial-strain formulations, the model combines concentric cylinders assemblage (CCA) homogenization with the experimentally validated Koo–Tallman resistivity–strain relation for nanofiller-modified matrices to derive closed-form expressions for axial and transverse resistivity changes. Unlike axial deformation, which produces relatively homogeneous strain states, radial deformation induces spatially varying strain fields and non-uniform electromechanical coupling within the matrix, providing new insight into the dominant role of radial loading and enabling analytical prediction of piezoresistive response across multiple deformation modes.