Control of Longitudinal Wave Propagation in Conical Periodic Structures

Conical periodic structure with single cells and multiple subcells is used to control longitudinal wave motion. It is well known that periodic structures by nature act as mechanical filters, allowing waves to propagate within specific frequency bands called pass bands, and blocking wave propagation within other frequency bands called stop bands. However, the conical geometry of cells and the use of conical subcells provide a conical periodic structure with the possibility of adjusting its impedance mismatch without the use of conventional active devices such as electromechanical, electrohydraulic, or piezoelectric actuators. The behavior of such a conical periodic structure is evaluated using single cells and cells with two, three, and four subcells. Theoretical predictions obtained by means of finite element modeling are compared with experimental results. Both experimental and theoretical results have converged in pointing to the effectiveness and the potential of using conical cells, and the concept of cells with subcells as tools for controlling longitudinal wave propagation in a periodic structure.