Measurements

Structure-Borne Noise

WHAT IS Structure-Borne Noise?

Structural vibration occurs when dynamic forces generated by compressors, pumps, and engines cause the deck beams to vibrate. This vibration leads to piping failures, poor equipment reliability, and safety concerns. The vibration is due to the structure being mechanically resonant. The term “resonance” occurs when dynamic forces coincide with the natural frequencies of the supporting structure. At resonance, the forces are amplified up to 20 times, and cause deck beams to vibrate above safe operating limits.

WHY CARE ABOUT Structure-Borne Noise?

Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines, and increasing structure durability.

DSRI carried out SBN measurements for several important projects in the marine sector for both public as well private sector undertakings. We frequently offer consultancy to premier yards like Mazagon Dockyard Limited (MDL), Garden Reach Ship-Builders and Engineers (GRSE), Hindustan Shipyard Limited (HSL) and world-leaders like Sauer Compressors, Burkhardt Compressors, Desmi Pumps, Caterpillar, Rolls-Royce and many more.

We offer end to end consultancy — from the design to factory acceptance trials(FATS) including preparing the testing procedures and Quality Assurance plans to meet the rigorous MIL-STDs as well other international specifications like ISO/IEC.

In addition, we also undertake acoustic-forensic studies to identify the hot-spots and suggest appropriate mitigation mechanism including damping treatments and vibration-isolation using resilient mounts & smart foundations.

Air-Borne Noise

WHAT IS Air-Borne Noise?

Sound is caused by vibrations which transmit through a medium and reach the ear or some other form of detecting device. Sound is measured either as sound pressure/power levels either at various frequencies.

Airborne sound (or airborne noise) is the sound that is transmitted through the air.

Typically, airborne sound might be generated by:

• Internal combusion or reciprocating machinery.
• Air moving equipments such as fans and ducts.
• Propellers and Wind Turbines.

OUR EXPERISE WITH Air-Borne Noise?

DSRI has extensive expertise in the measurement, mathematical modelling and engineering noise control of machinery noise, propulsion noise and flow-induced noises. We also advise on the prediction and control of noise and vibration in marine, aerospace & automobiles including interior trim design.

We helped several companies prepare the testing procedures and Quality Assurance plans to meet the rigorous MIL-STDs as well other international specifications like ISO/IEC. We also assisted several navies in drafting custom standards for machinery as well as propulsion noises. We carry out speech intelligibility testing of PA systems in aeroplanes and helicopters.

We have measured and assessed crew noise exposures in civil aircraft in light aircraft used for pilot training, and in helicopters used by police air support units. Crew noise exposures are the result not only of ambient noise in the cockpit, but also the noise of speech from the intercom and radio heard through headsets or flying helmets, with or without active noise reduction.

Other projects undertaken by DSRI include the design/prediction of acoustics for bullard tugs, frigates, submarines, VIP aircrafts and a number of unusual applied research projects on the general topic of internal noise and communications.

Under-water Radiated Noise

WHAT IS Under-water Radiated Noise?

We aid several navies and shipyards in carrying out underwater ranging studies for submarines and surface ships as per STANAG 1136. Please contact us for further details.

We also offer noise predictions during the design phase through popular numerical techniques like FEA (Finite Element Analysis), BEM (Boundary Element Method) and SEA (Statistical Energy Analysis). Please visit our Advanced Engineering page.