Experimental analysis of wave propagation in periodic grid-like structures

This work presents the experimental investigations of wave propagation in two-dimensional (2D) periodic lattice structures. Periodic structures in general feature unique wave propagation characteristics, whereby waves are allowed to propagate only in specific frequency bands, while they are attenuated at frequencies belonging to the so-called "band gap". This behavior makes periodic structures attractive candidates as passive vibration isolators. The band-gap characteristics of a rectangular lattice are here investigated. An optimized configuration is found through a numerical model previously developed and presented. An aluminum specimen is manufactured by machining, and tested for validation and demonstration purposes. The wave field in the lattice is generated by a point harmonic excitation at various frequencies, and it is measured through a Scanning Laser Vibrometer. The objective of the tests is the validation of the numerical model and the demonstration of the unique filtering properties of the considered structural assembly.