Numerical realization of a semi-active virtual acoustic black hole effect

Abstract

Noise mitigation by means of the acoustic black hole (ABH) effect is a well-known engineering solution. However, the conventional method of applying ABH effect which requires modification of the structure geometry has various limitations which encourage the research of virtual ABH concept. In this study, the effect of ABH was applied through introducing virtual stiffness by a shunt circuit. According to the force-voltage electric analogy, stiffness has an inverse relationship with capacitance. So that the ABH effect can be virtually realized by following a power law profile using an array of independent capacitive shunts. The concept is studied through finite element simulation developing a macro code in ANSYS Parametric Design Language (APDL). To evaluate the influence of capacitance profile on the acoustic radiated power, parametric studies are conducted. Based on the results of the parametric studies, the capacitance profile is tuned for minimum radiated power. It is revealed that the virtual acoustic black hole (ABH) effect can offer 10.29%, 6.37%, and 7.47% reduction in the radiated power from the first to the last targeted mode, respectively. The virtual ABH effect introduced in this study can be used for semi-active structural noise isolation without any weight or manufacturing penalty.

Realization of an autonomous virtual acoustic black hole with piezoelectric patches

“…In these papers, a large number of piezoelectric devices were used to digitally and gradually modify the beam's Young modulus. In the same spirit, Soleimanian et al [23] reproduced the variations in ABH thickness with successive capacitors, which led to a maximum of 11% power radiation reduction in numerical simulations. Recently, we proposed the concept of a virtual ABH (VABH) where the mechanical ABH impedance, derived with a state-space approach [24], is simulated digitally.…”

“…where α u and α ϕ represent the projected modes α on the coupling matrix Θ when only the u and ϕ components are retained, respectively. Substituting these relations in (23) and expressing η as a function of V a gives…”

Common transmission theory and wide application

“…To figure out the bending and contact stress for material selection, the load and torque requirements are planned to be defined at the beginning. The diametral pitch and gear ratio need to be designed for further calculation using equations ( 1) and (2).…”

“…For equation (1), N is the number of teeth and D is the pitch diameter. For equation (2), NG is the teeth number of gear and NP is the teeth number of pinion.…”

“…The transmission is widely applied in the vehicle manufacturing industry and power delivery industry. For the common commercial car and heavy-duty vehicle, the transmission system can be applied to change the speed and torque between the input engine and output shaft [2]. A belt/chain structure is one of the common solutions for the transmission.…”