Most practicing professionals in Noise and Vibration domain know this basic rule of mitigation; to address an issue, work at the source, path, or the receiver - there are many work arounds that can be adapted based on the boundary conditions and extent of attenuation required.


Addressing N&V issues at their source is an active and effective approach; but this also means that you are really working right at the point of generation of these sources, meaning that you may have to look at the very reason by which vibrations and consequently the noise energies are generated. A design review of the product / source may be required, to revisit, review, and re-work on all the contributing factors that finally results in higher vibration and noise. A finished product and its design are hard to modify, and a design change may have compounding effects in the entire manufacturing process; sometimes keeping strict noise & vibration targets also gets into the value proposition and realisable cost of the product.


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Few active vibration isolation examples

The receiver end isolation is mostly effective for noise sources. We all know and use many everyday gadgets such as earmuffs, earplugs and even active noise cancellation head gears. These are localised hearing protection schemes that work effectively on individual but has their limitations in term long-term wearing and are prone to cause accidents to the user as the sensitivity of hearing is lowered with these gadgets.


The term isolation in both noise and vibration is to technically create a disconnect between the source and the receiver; these may include absorbing a considerable amount energy at the closest point of the source and / or to create an absolute cut-off path by introducing barriers that do not allow the propagation either though the connected structural members or other medium. Again, the operational requirements of any of these products that are generating higher vibration or noise does come in to play while implementing isolation plans, such as heat dissipation, approach, accessibility and so on.


Whole body and hand vibrations are also partly addressed depending on the exposure type and considering the man-machine interface aspects. A variety of visco-elastic members are used as isolation layers to attenuate vibrations reaching the person who is exposed to these environments; the challenges of reduced sensitivity and operational restraining factors continue to downplay the solutions available.


A combination of spring and mass in right proportions is all that exists in any of noise and vibration isolation. The damping characteristics of the isolation material adds to the time constants that play key role in energy dissipation and helps sustain acceptable limits of noise and vibrations for the given case and conditions.


The uses of tuned mass damper and active dampers work well for specific cases where the contributing sources are of lower frequency and have consistent phase response as a single degree of freedom system. MSS and other tuned dampers in rail transport system work effectively for a set of considered frequency but fail to address shock loads and one-off events.


An intelligent, adaptive and engineered combination of isolation methods is the right approach to address many of real-life Noise and Vibration problems - one solution doesn't fit all and not any of these solutions bring an absolute technical closure to a given problem. Merit of each case shall be assessed to implement solutions at source, path and /or receiver taking all workability into consideration.


From Metro rail to heavy machinery, from earth moving equipment to laser lithography, NV Dynamics works on end-to-end solution aspects of noise and vibration isolation and mitigation; the combined approach of modelling, calculations & testing combined with applied engineering sense have made us to approach some of the complex real-life N&V issues.