Vibration analysis of beams coupled with evenly spaced acoustic black hole pillars: Experimental and numerical insights

Stiffened structures are commonly used in engineering applications such as aerospace, marine, automotive and civil engineering. Vibration control of these structures is a critical area of research that aims to enhance their reliability and durability by effectively mitigating vibrations. This work aims to demonstrate the potential of integrating acoustic black holes (ABHs) into stiffened structures by altering only the shape of the stiffeners without adding mass to the host structure or compromising structural integrity. Towards this aim, experimental and numerical analyses are conducted on finite beams coupled with ABH or rectangular pillars. The ABH design has the same mass and moment of inertia at the contact point as the rectangular pillars to establish a comparison. Three configurations are tested for both cases: without damping layers, with viscoelastic damping layers, and constrained viscoelastic damping layers. Experimental results revealed that the beam with ABH pillars, particularly when paired with constrained viscoelastic damping layers, exhibited higher vibration mitigation (up to 33 dB) compared to the vibrational response of a beam with the rectangular pillar with the same constrained viscoelastic damping layers. Numerical simulations using finite element models supported the experimental findings, and provided insight into the vibration mitigation mechanism by examining the mode shapes of the two considered beams. The combined experimental and numeral results highlight the potential of ABH stiffeners as an innovative solution for vibration control in stiffened structures.