Simulation and Application of Lightweight Damping Sandwich Material for I.C. Engines

Making lighter engines is in the agenda of all OEMs in order to make their cars lighter and to reduce CO₂ emission based on regulations. On the other hand, the noise regulations are getting more stringent and the customer impression of interior sounds is still an important aspect in vehicle development. Vehicle noise legislation has been revised numerous times since it was first established in February 1970. The latest revision in EU legislation introduces a revised test method which is used to enforce diminishing noise limits in three phases (EU Regulation No. 540/2014). Since 2016 the noise limit for passenger cars has been 72 dB(A). It will be reduced to 70 dB(A) in 2020 and to 68 dB(A) in 2024. These vehicle pass by noise limits cascade down to limitations on engine noise.

New engine designs face a trade-off between a lightweight design and fulfilling the NVH targets. The conventional design updates are done by adding ribs and usually mass to the engine. On the other hand, the advanced lightweight materials with high damping characteristics have been developed which help lightweight good NVH design. Nonetheless the correct use of these materials requires proper material data measurement and proper material, thickness selection. The temperature effect should not be ignored as well specially in engine application. In this paper, the method of measuring the material properties is explained. Then a simulation model is introduced and validated for the application of such a material to the case of a rectangular beam. Finally, the application of such a material is presented for an engine front cover. The high damping effect is shown, and the correlation of models to measurement for two different temperatures is shown. This method can be used to select the damping and materials and improve the engine NVH.