Analysis of Traveling Wave Properties of Mechanical Metamaterial Structures: Simulation and Experiment

The steady-state response of harmonically excited structures can exhibit a significant traveling wave ratio. Local excitation of structures with locally increased damping or even structures that are proportionally damped, for example, lead to wave propagation phenomena. Since damping distribution plays a key role in formation of traveling waves, it needs to be considered in the dynamic analysis. In this chapter, we analyze the steady-state vibration behavior of 3D printed metamaterial structures. The investigated parts are made of resin and steel by laser sintering. The dynamic analysis with special attention to traveling wave effects is simulated based on finite element method and experimentally validated. Due to the complex geometry of the metamaterial structure, fine meshing is necessary for accurate results, making reduction techniques inevitable. A combination of modal reduction and dynamic condensation is used to obtain the simulated results. In the laboratory, laser scanning vibrometry is used to measure the entire structure and validate the simulations. We show in both simulation and experiment that the studied structures exhibit both standing waves with locally fixed nodal lines and traveling nodal lines with significant traveling wave content, depending on the excitation frequency.