OEM & Lieferant Ausgabe 2/2019 - OEM & Supplier 2/2019 by VEK Publishing

162 Lightweight Ultralight – Low areal weight products to improve the acoustic performance of modern cars By Bernd Fuhrmann, Global Product Manager, Sika Automotive With governments setting stronger CO 2 emissions standards and consumers demanding better fuel efficiency, building lighter cars is of critical importance for OEMs. To achieve this, engineers are choosing non-traditional ma- terials such as aluminum, magnesium and carbon fiber reinforced plastics. Lighter gauge metal sheets are also being used, but these materials create unique challenges in vehicle assembly processes and introduce unwanted effects on durability, acoustics, vehicle dynamics and crash performance. This is when new innovative damping materials come into play, they allow manufacturers to obtain better acoustic performance all the while offering a lower area density than typical structure born noise damping products. Structure-borne sound attenuation is of great importance for the car industry A modern car has to be able to respond to customers’ expectations regarding comfort in NVH behavior (NVH: Noise, Vibration, Harsh- ness). Through technological transformation towards drive electrification and autonomic riving, new challenges emerge also in the area of attenuation of structure-borne noises. Attenuation of mechanical energy taken from a vibrating system is usually transformed into heat. In this way, waves in the structure be- come weakened and amplitude in resonance areas is reduced. The usual method to accom- plish this includes the application of materials characterized with very good damping prop- erties. Necessary conditions include design optimization as well as knowledge of the vi- brational behaviour of the car gained from sim- ulations or laser vibrometry studies targeted at the reduction of vibrations as well as knowing the damping properties of the used material in varies frequency and temperature ranges. Application of attenuation material on vehicle body constitutes an essential tool to improve acoustic comfort and thus subjective assess- ment of vehicle value. Dampingmaterials have been developed with the reduction of vibra- tion energy in the vehicle body in mind. Product Range SikaDamp ® solutions comprise a broad family of sound damping products based on elas- tomers, bitumen or butyl, which can also be coupled with a constraining layer. They are de- signed for excellent weight-to-performance ratios, while still providing industry-leading damping performance. The full range of solu- tions allow effective structure-borne noise reduction of car body elements and improved targeted acoustics without compromising weight. Meeting emission goals The newest “Ultralight” technology was cre- ated with the goal in mind of helping OEMs design lighter, more fuel-efficient cars with- out compromising on acoustic performance. Through the usage of ultra-low density damping material combined with constraint layer technology, we’ve been able to achieve an areal weight of 1.1 kg/m 2 compared to 5 kg/ m 2 for typical NVH products. This results in a weight savings of up to 80%. A midsize sedan has about 2 m 2 of damping material, so the av- erage weight saving potential is around 7 kg per vehiclemaking for amore fuel-efficient car. Performance Along with this extraordinary weight perfor- mance, the SikaDamp Ultralight comes with an exceptionally high damping performance that is comparable with traditional Alu-Butyl con- strained layer systems. In combinationwith an alternative top layers, the material is also suit- able for paint shop application on corrugated surfaces at a still above-average weight and damping performance. Process convenience Not only does this product performs well, it’s also very convenient to implement in a production line as it does not require any up- dated processes on the customer side. The ap- plication process is as easy as for other NVH products. Sika Automotive  www.sikaautomotive.com SikaDamp-Ultralight  bit.ly/2Ove4E7 Websites Image: © Sika Automotive SikaDamp ® -Ultralight on a lightweight carbon component