Acoustic black hole (ABH) is a well-established phenomenon in the field of acoustic. It consists in confining the vibration in the structure edge by controlling its thickness profile. This paper aims to achieve acoustic black-hole-like phenomenon by implementing a profile gradient instead of a thickness variation. To accomplish this, a composite sandwich beam with a functionally graded core is designed and fabricated. The results are demonstrated experimentally. The core of the sandwich beam is a 3D printed cellular material designed following a Voronoï architecture. The property gradient is implemented by varying the size of the cells in the longitudinal direction. The beam is tested in a forced vibration setup, in a clamped-free configuration, under chirp excitation. The 8 first modes of this structure are compared to a finite element model. The presence of ABH-like behavior is demonstrated by monitoring the mode shape of the structure. Some non-linearity and the effect of the electro-dynamic shaker are discussed to explain a shift of modal frequencies between the numerical and experimental values.
Associate Professor, Rose-Hulman Institute of Technology
Professional interests include undergraduate engineering education, finite element modeling, ground-borne vibrations, vibrations of musical instruments, and dynamics of toys.
