Stiffening effects of high-frequency excitation: experiments for an axially loaded beam

According to theoretical predictions one can change the effective stiffness or natural frequency of an elastic structure by employing harmonic excitation of very high frequency. Here we examine this effect for a hinged-hinged beam subjected to longitudinal harmonic excitation. A simple analytical expression is presented, that relates the effective natural frequencies of the beam to the intensity of harmonic ex-citation. Experiments performed with a laboratory beam confirm the general tendency of this prediction, though there are discrepancies that cannot be explained in the framework of the linear Galerkin-discretised beam model.