Nonlinear Dynamic Response of Nanocomposite Cantilever Beams

The nonlinear dynamic response of carbon nanotube (CNT) nanocomposite cantilevers is experimentally and theoretically investigated. Nanocomposite cantilevers made of a thermoplastic polymer and high aspect ratio CNTs are subject to a primary resonance base excitation. The experimentally obtained frequencyresponse curves highlight the effects of the CNT/polymer stick-slip energy dissipation on the nonlinear macroscopic dynamic response of the nanocomposite beams. The hysteresis arising from the nanostructural stick-slip gives rise to a change of nonlinearity dominated by the flexural curvature hardening effect towards a softening behavior at low amplitudes. The CNT/polymer frictional sliding hysteresis is here described by a hysteretic restoring force in the context of the nonlinear Euler- Bernoulli beam theory. An initial parametric analysis shows the capability of the model to capture qualitatively the softening-hardening frequency response trend.