Browse Publications Technical Papers 2019-01-1496
2019-06-05

Effectiveness of Power-law Profile Indentations on Structure-Borne Noise 2019-01-1496

With the focus shifting towards to the electric drives, owing to the stringent requirements for noise and vibrations, different measures are being taken to reduce the energy loss from the system via noise or heat dissipation but the conventional N&V approach of increasing the stiffness of the flexible component and reducing the mass may not always help in avoiding the resonance condition with the unwanted excitations owing to a wide range of operating range for motors and absence of engine noise makes it worse. Apart from any structural modifications, implementation of sound barriers like acoustic covers for sound absorption is also generally adopted for noise treatment. Locally modifying the structure thickness between two spatial locations helps in decreasing the reflection coefficient at the terminating edges thus reducing reflection of flexural waves. Power law profiles where the thickness gradually decreases along the space with an order greater than 1 are found to be more effective in reducing wave reflections. Recent research on locally modifying the wave velocity by implementing power law profiles within the structure have shown a significant reduction in noise levels. Using power law profiles concept also known as acoustic black hole seems to be another way to reduce or tune the structure borne noise. This concept can be very well implemented leading to effective usage of acoustic covers or acoustic treatments with less acoustic materials. This paper discusses a simulation approach to study the effectiveness of such features on flexible components on the near and far field response. Studies are done using both the approach i.e. directly getting the frequency response and running transient analysis to capture the effects more accurately. Other studies like placement and size of such features are also discussed. KEYWORDS: Power law profile, Acoustic black hole, Frequency Response, Radiated noise, Damping treatment REFERENCE: Acoustic black holes and their applications for vibration damping and sound absorption, V.V. Krylov

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