This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Ecofelt Hybrid Stiff NVH Tunable Insulator
Technical Paper
2018-01-1494
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Whenever the noise source level or the expected acoustic comfort increases for diesel engines for example or for premium petrol vehicles, the required weight per unit area can be specified above 2000 g/m2 for the equivalent barrier of a mixed absorbing-insulating noise treatment. For an ABA foam/heavy layer/felt insulator, this is not a big issue, one has to increase the intermediate heavy layer weight. For hybrid stiff compressed felt backfoamed standard technologies, going above 2000 g/m2 is critical due to absorption properties loss following much too high airflow resistances and progressive porosity loss (above 250 kg/m3) as well as too high bending stiffness presenting resonant modes progressively and assembly manipulation issues. Last but not least, compressed felts begin to present too high costs at these weights against those of the heavy layers of ABA systems.
The chips urethanes give an answer to the aforementioned issues for high weights above 2000 g/m2 up to 3500 g/m2 typically for hybrid stiff backfoamed concepts in the same mold and with the same process as lower weights (called Polyfoam). The acoustic properties of these highly compressed chips urethane with standard isocyanate binder are good, even better with bi-component fibers, but the costs remain often too high against ABA systems. The Ecofelt tunable insulator is another answer to this high weights range above 2000 g/m2 up to 3500 g/m2, and even above, while maintaining the same processes and molds as for the light standard hybrid stiff insulators. The lay-up consists of a first compressed stiff felt layer of 1300 g/m2 8 mm thick typically backed by the powdered scraps of 400 g/m2 to 1200 g/m2 typically (and above) and backfoamed by an injected soft PUR foam of 50 kg/m3 classically.
The mass per unit area of the scraps allows to adjust the insulation performance and also to localize it where needed, whenever the upper felt is sufficiently stiff. Knowing that these carpet and heavy layer scraps are almost always available in manufacturing plants due to the 30% average cut out waste of carpets or trunk trims processes, these recycled materials are almost for free as long as they are not transported. This paper will show the acoustic performance of this Ecofelt tunable insulator technology on both laboratory flat samples and dash insulator parts measured in coupled reverberant rooms or in vehicle and also simulated using poroelastic finite elements.
Authors
Topic
Citation
Duval, A., Crignon, G., Goret, M., Lemaire, D. et al., "Ecofelt Hybrid Stiff NVH Tunable Insulator," SAE Technical Paper 2018-01-1494, 2018, https://doi.org/10.4271/2018-01-1494.Also In
References
- Duval , A. Acoustic Light-Weight Concept Congrès SIA Confort Automobile et Ferroviaire Le Mans, France 2002
- Duval , A. , Rondeau , J-F. , Deshayes , G. , Lhuillier , F. et al. Generalized Light-Weight Concept: A Comprehensive Acoustic Package Weight Reduction Strategy Congrès SIA Confort Automobile et Ferroviaire Le Mans, France 2006
- Crignon , G. FF2T the Trèves’s Answer to the Weight Reduction Congrès SIA Confort Automobile et Ferroviaire Le Mans, France 2008
- Duval , A. and Bischoff , L. Stiff Textiles or Felts Glued on Light Impervious Layers: A New "Green" Light Fiber Septum Technology SAPEM 2011 Conference Ferrara, Italy 2011
- Duval , A. , Rondeau , J-F. , Dejaeger , L. , Lhuillier , F. et al. Generalized Light-Weight Concepts: A New Insulator 3D Optimization Procedure SAE Technical Paper 2013-01-1947 2013
- Duval , A. , Crignon , G. , Goret , M. , and Roux , M. Comprehensive Hybrid Stiff Insulators Family: The Chips Urethane Contribution SAE Technical Paper 2017-01-1883 2017 10.4271/2017-01-1883
- Duval , A. , Crignon , G. , Goret , M. , and Lemaire , D. Upgrading Hybrid Stiff Insulators Performance through Tailored Solid Inclusions Localization: The Polyfoam and Ecofelt Solutions SAPEM 2017 Conference Le Mans, France 2017
- Allard , J.-F. and Atalla , N. Propagation of Sound in Porous Media Second John Wiley & Sons 2009
- Atalla , N. , Panneton , R. , and Debergue , P. A Mixed Displacement-Pressure Formulation for Poroelastic Materials The Journal of the Acoustical Society of America 104 3 1444 1452 1998
- Mebarek , L. , Lullier , S. , Kobayashi , Y. , and Blanchet , D. Modelling of Transmission Loss for Trimmed Vehicle Components JSAE Annual Congress Japan 2007
- Omrani , A. , Mebarek , L. , and M.A Hamdi Transmission Loss Modeling of Trimmed Vehicle Components ISMA Leuven 2006
- Duval , A. , Dejaeger , L. , Baratier , J. , and Rondeau , J-F. Structureborne and Airborne Insertion Loss Simulation of Trimmed Curved and Flat Panels Using Rayon-VTM-TL: Implications for the 3D Design of Insulators Congrès SIA Confort Automobile et Ferroviaire Le Mans, France 2008
- Duval , A. , Dejaeger , L. , Morgenstern , Ch. , and Rondeau J-F Novel Technique for the Introduction of Curved Trims in SEA / Virtual SEA Models Using Poroelastic Finite Elements in the Middle (and High) Frequency Range Congrès SIA Confort Automobile et Ferroviaire Le Mans, France 2010
- Lesueur , C. Rayonnement Acoustique des Structures Ed. Eyrolles 1988
- Dauchez , N. , Sahraoui , S. , and Atalla , N. Convergence of Poroelastic Finite Elements Based on Biot Displacement Formulation The Journal of the Acoustical Society of America 109 1 33 40 2001