Developing Novel Sound Solutions for Automotive NVH (Noise, Vibration and Harshness)

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In 2016, 88 million automobiles were sold across the world which is 4.8% more than the previous year.1 Today, the automotive industry has become increasingly competitive with customers demanding more environmentally friendly, safe, efficient and comfortable vehicles.

Noise, vibration and harshness (NVH) reduction are factors that provide more comfort.2 In order to reduce NVH in the automotive sector, Tecman is investing in new facilities to develop bespoke acoustic insulation solutions.

Noisy Vehicles are Hazardous for Drivers, Passengers and Pedestrians

Any unwanted sound either inside or outside the vehicle can be referred to as noise; mechanical oscillation is referred to as vibration, and discomfort or severity of the noise and vibration is referred to as harshness.3 The overall perception of cars and trucks is affected by the NVH and this NVH is also considered as one of the major factors in vehicle design.

High levels of noise and vibration over a long period of time can be hazardous for occupants, but quieter, more comfortable vehicles can be produced by reducing NVH.3 In addition, environmental noise pollution can be reduced by reducing NVH in vehicles; such pollution is associated with increased cardiovascular risk and sleep disturbances.4, 5

As noise and vibration from the engine was the major source of noise in the vehicle, the first NVH studies were applied to reduce these two factors. Other sources of noise like aerodynamic noise, road noise and braking noise have become more important, as the level of noise from the engine has been significantly reduced over the years of car development. Along with the wheels and drivetrain, the engine and engine accessories are also important sources of vibration in vehicles.2, 6 While designing their vehicles, automotive Manufacturers should consider all sources of noise and vibration to reduce the effects of NVH using intelligent engineering and innovative materials.

Advanced Acoustic Insulation Materials Reduce Vehicle Noise

Early attempts to reduce noise consisted of filling panels in roofs, floors and doors with as much insulation as possible. Now automotive panels are precisely designed to provide acoustic performance and advanced acoustic materials are utilized to reduce NVH.

Significant improvements in the performance of sound absorbing materials were possible due to recent advances in Materials Science. As a result, a large variety of acoustic materials are now commercially available, including porous metals, recycled materials, biopolymers, natural fibers, composites and smart materials.7, 8, 9

The different types of available acoustic insulation materials offer high sound absorption coefficients, but their exact performances differ based on mounting methods, finish, thickness, material composition and sound frequency. Sound absorbing materials usually consist of solids with channels or cavities that trap air, enabling sound waves to enter the material.7, 8, 9

The fibers of the material begin to vibrate when the sound waves enter the material and they thus rub against each other due to this vibration, resulting in heat from friction. In this manner, the energy from the sound vibration is converted to heat that dissipates.10

Tecman Provide a Range of Bespoke Acoustic Insulation Solutions

The majority of commercially available sound-absorbing materials are fiber based, as fibrous provide cavities between the fibers that allow sound waves to enter. The fibers can move against each other, allowing the energy of the sound waves to be converted to friction easily.

Tecman provides acoustic insulation pads made using a range of fibrous acoustic insulation materials. Although the properties of the individual materials vary, automotive insulation solutions from Tecman are all designed to provide highly efficient acoustic absorption while reducing the weight and environmental impact of vehicles. The acoustic materials provided by Tecman include natural fibers, multi-layer fine fibers, lightweight Neptune and high-loft insulation materials.11, 12

Neptune is the latest NVH product introduced into Tecman’s product range. While being very lightweight (from 150 g/m2 at a thickness of 12 mm), Neptune is an ultra-fine fiber that offers high sound absorption performance. The combination of light weight and high performance in Neptune is possible as the material comprises of hollow, grooved ultra-microfiber polypropylene and polyester that has been flexurally laid.13

Recently, Tecman has invested in new machinery and processes and this investment has increased the capacity as well as the size of acoustic insulation components that can be manufactured. The new machinery stamps out parts up to 520 mm x 1500 mm (the previous capacity was 320 mm x 1000 mm). To aid application, bespoke components are available in various presentation formations, such as scrim lamination, scrim variations, clip insertion, zone coated adhesive, strip coated adhesive, tape application, sealed, crimped and open edges.13

For over 25 years, Tecman has been providing sophisticated solutions for the automotive industry, and its clients already include some of the top original equipment Manufacturers and tier-one Suppliers in Europe and beyond. The new investment in Tecman’s conversion facility further increases its ability to provide bespoke acoustic insulation solutions to the automotive sector that help to combat NVH.

References

  1. https://www.strategyand.pwc.com/trend/2017-automotive-industry-trends  Accessed July 12th, 2017.
  2. Panza MA, ‘A Review of Experimental Techniques for NVH Analysis on a Commercial Vehicle’ Energy Procedia 82:1017-1023, 2015.
  3. Ab Aziz SA, Sohaimi RM, Pu’ad MH, Mohd Yaman MA, ‘Noise, Vibration and Harshness (NVH) Study on Malaysian Armed Forces (MAF) Tactical Vehicle’ Applied Mechanics and Materials, 165:165-169, 2012
  4. Jakovljević B, Lojević G, Paunović K, Stojanov V, ‘Road traffic noise and sleep disturbances in an urban population: Cross–sectional study.’ Croatian Medical Journal 47(1):125-33, 2006.
  5. Babisch W, ‘Transportation noise and cardiovascular risk: Updated review and synthesis of epidemiological studies indicate that the evidence has increased.’ Noise and Health, 8(30):1-29, 2006.
  6. http://www.autoserviceprofessional.com/article/93006/noise-vibration-harshness-chasing-the-irritant-gremlins  Accessed July 12th, 2017.
  7. Al-Zubi M, Ayorinde E, Alshabatat N, Dundar M, Murty Y, ‘Sound and vibration considerations of some materials for automotive engineering applications’ American Journal of Applied Sciences 11(10): 1784-1797, 2014.
  8. Mohanty AR, Acoustical Materials for Automotive NVH Reduction. In: Munjal M.L. (eds) IUTAM Symposium on Designing for Quietness. Solid Mechanics and Its Applications, vol 102. Springer, Dordrecht, 2002.
  9. Arenas JP, Crocker MJ, ‘Recent trends in porous sound-absorbing materials’ Sound & Vibration 44:12-17, 2010.
  10. https://www.acousticalsurfaces.com/acoustic_IOI/101_7.htm  Accessed July 12th, 2017.
  11. http://www.tecmanuk.com/industry/industries/automotive/automotive-vehicle-acoustics/  Accessed July 12th, 2017.
  12. http://www.tecmanuk.com/news/importantance-of-nvh-reduction/  Accessed July 12th, 2017.
  13. http://www.tecmanuk.com/news/neptune-automotive-acoustic-insulation-pads/  Accessed July 12th, 2017.

This information has been sourced, reviewed and adapted from materials provided by Tecman Speciality Materials.

For more information on this source, please visit Tecman Speciality Materials.

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