Vibration transmissibility and damping behaviour for auxetic and conventional foams under linear and nonlinear regimes

This work describes the vibration transmissibility behaviour in conventional and auxetic (negative Poisson's ratio) foams under low and high amplitude vibrations. Auxetic foam pads were manufactured from conventional open cell PU-PE based blocks using an alternative manufacturing process to the one currently used in the mainstream literature. The dynamic behaviour of both conventional and auxetic porous materials was assessed within the frequency bandwidth 5-500 Hz using a base excitation technique with a calibrated seismic mass. The foam pads were subjected to white noise broadband excitation at low dynamic strain, followed by a sine sweep around the resonance of the foam-mass system. The experimental data have been used to perform an inverse identification of the nonlinear dependence of the foam permeability versus the amplitude and frequency of excitation using a single-degree-of-freedom poroelastic vibration model. The auxetic foam shows higher dynamic stiffness and enhanced viscous dissipation characteristics, in particular when subjected to nonlinear vibration loading.