Control of wave propagation in periodic composite rods using shape memory inserts

Longitudinal wave propagation is controlled using shape memory inserts plac ed periodically along rods. The inserts act as sources of impedance mismatc h with tunable characteristics. Such characteristics are attributed to the unique behavior of the shape memory alloy whereby the elastic modulus of th e inserts cart be varied rip to three times as the alloy undergoes a phase transformation from martensite to austenite. With such control lable capabi lity, the inserts can introduce the proper impedance mismatch necessary to impede the wave propagation along the rods. An analytical model is presente d to study the attenuation capabilities of the composite rods and to determ ine the influence of the various design parameters of the inserts that can control the width of the pass and stop-bands. The numerical results demonst rate the potential of shape memory alloys in controlling the dynamics of wa ve propagation in rods. Furthermore, the obtained results provide a guideli ne for designing inserts that are capable of filtering out selected excitat ion frequencies through proper adjustment of the geometry of the inserts as well as their activation strategies.