Numerical Analysis of Wave Propagation in Functionally Graded 1-D Acoustic Black Hole via Viscoelastic Local Interaction Simulation Approach
Recent research has shown that the acoustic black hole (ABH) effect provides wave focalization and dissipation in thin-walled structures. The design and implementation of functionally graded acoustic black hole (FG-ABH) are presented in this work. Two kinds of the FG-ABHs are demonstrated, which are axially graded ABHs and the thickness graded ABHs, respectively. The FG-ABHs are capable to be manufactured by 3D printing tech using the Objet Connex 500 printer. The one-dimensional FG-ABH has both diminishing thickness and elastic modulus from the uniform part to the tip of the wedge. Wave propagation, attenuation and reflection in the presented FG-ABHs are investigated utilizing a viscoelastic University of Michigan’s Local Interaction Simulation Approach (UM/LISA). The damping effect of the materials is included based on Kelvin-Voigt viscoelasticity theory, in which the damping coefficients are obtained by both numerical and experimental model updating. Finally, the reflection coefficients of FG-ABHs are analyzed by LISA and compared to that of the traditional ABH structure with homogeneous material. It indicates that the FG-ABHs enhance the ABH effects since they achieve lower reflection.
