Reflection coefficients of Enhanced Acoustic Black Holes at a beam termination

The design of lightweight and stiff structures with high vibration damping properties is an important issue in mechanical engineering. The insertion of Acoustic Black Holes (ABH) in a flat panel or in a beam termination is an innovative technique for passive structural vibration damping without added mass. ABH consist in local heterogeneities of the stiffness and the damping and are known as efficient absorbers for flexural waves above their cut-on frequency. The goal of the paper is to identify and to push the current limitations of this existing strategy by developing "enhanced acoustic black holes" (eABH) absorbers based on the integration of thermal adaptive systems. The capability of such techniques to enhance the control of the flexural rigidity and the local damping is investigated numerically. The reflection coefficients, R, of several architectures of ABH beam termination are computed using the Impedance Matrix method. Such a method is adapted to the accurate computation of R of a structural wave guide with varying properties. Comparing R of several architectures allows us to discuss the potentialities of such eABH.