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 excitat ion of very high frequency. Here we examine this effect for a hinged-hinged beam subjected to longitudinal harmonic excitation. A simple analytical ex pression is presented, that relates the effective natural frequencies of th e beam to the intensity of harmonic excitation. Experiments performed with a laboratory beam confirm the general tendency of this prediction, though t here are discrepancies that cannot be explained in the framework of the lin ear Galerkin-discretized beam model.