It is known that in the design of quieter mechanical systems, vibration and noise control play important roles. Recently, acoustic black holes have been effectively used for structural design in controlling vibration and noise. An acoustic black hole is a power-law tapered profile to reduce phase and group velocities of wave propagation to zero. Additionally, the vibration energy at the location of acoustic black hole increases due to the gradual reduction of its thickness. The vibration damping, sound reduction, and vibration energy harvesting are the major applications in structural design with acoustic black holes. In this paper, a review of basic theoretical, numerical, and experimental studies on the applications of acoustic black holes is presented. In addition, the influences of the various geometrical parameters and the configuration of acoustic black holes are presented. The studies show that the use of acoustic black holes results in an effective control of vibration and noise. It is seen that the acoustic black holes have a great potential for quiet design of complex structures.

The seismic performance and the influence of debonded longitudinal reinforcements at the footing on the precast concrete columns connected with the embedded grouted corrugated sleeve were investigated experimentally in this research. Low cyclic loading tests were carried out on eight bending columns and four shear columns, considering the designed parameters of the partial debonding of the longitudinal reinforcements above the column–foundation interface, the axial load index, and the strength of the stirrups. Experimental results indicate that the partial debonding of the longitudinal reinforcements heavily influenced the damage spreading of the bending columns, but does not affect the damages of the shear columns. Compared to the columns without debonded longitudinal reinforcements, the seismic behaviors in terms of the ductility and energy dissipation can be improved clearly by the partial debonding of the longitudinal reinforcements for bending columns, but there was no clear improvement for shear columns. In addition, with the decrease of the axial load index or the increase of the strength of the stirrups, the seismic behaviors of the precast columns with the partial debonding of the longitudinal reinforcements are improved largely.

Vibration and noise control of mechanical structures play an important role in the design of many industrial systems. Recently, Acoustic Black Hole (ABH), a new passive structural modification approach to control vibration and noise from mechanical structures has been developed and studied. An ABH is usually a power-law taper profile due to which the wave velocity gradually reduces to zero. Also, the vibration energy is concentrated at the locations of ABH due to the reduction of wavelength. The exponent and parameter of the power-law curve define the geometry of an ABH. This paper presents an investigation of the influence of the geometry of ABH on the sound radiation from vibrating structures. This paper presents both numerical and experimental work on the on the near field sound radiation from vibrating cantilever beams containing ABH.

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As the Northwest passage becomes more frequently traveled by commercial and business interests, it is becoming important to increase existing methods for safety at sea in harsh Arctic conditions. In order to identify ice-floe movements in the Arctic, acoustical signatures for ice behaviors need to be identified and analyzed. Being able to identify the acoustic signature of ice cracking in real-time will help vessels navigate the arctic by identifying moving ice-floes and monitoring present ice conditions. This study identifies a novel method for detecting thermal cracking in ice, ice fracturing, and ice shearing events in an anechoic chamber. Comparing the power spectra and identified peak frequencies against empirically collected data from previous studies, this methodology aims to recreate the arctic environment in a lab without travel to the region for baseline data collection. Furthermore, based on a literature review, little power spectra data exist. The data collected from this study will add to the creation of a baseline identification for future ice fracture studies. Observations are made on the collected data which can be used to improve navigational methods for safety at sea.