Design and dynamic characterization of lightweight materials that meet automotive NVH targets. Acoustic Resonant Meta-materials.

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1 Design and dynamic characterization of lightweight materials that meet automotive NVH targets Acoustic Resonant Meta-materials Bert Pluymers Department of Mechanical Engineering Celestijnenlaan 300B box Leuven, Belgium

2 Need to reduce emissions

3 Solution in aerospace: lightweight % 50% 757/767 3% 747 1% Materials Composite Steel Titanium Aluminum Miscellaneous Copyright 2012 Boeing.

4 Lightweight materials Composite panels Honeycomb panels Woven carbon fibres Motivation Lower weight Higher strength Price to pay Worse NVH properties Different (complex) dynamics

5 TL of lightweight materials similar stiffness, lower mass f e1 f g strongly reduced insulation Static stiffness Mass Coincidence Bending stiffness Mass Damping f e1 f g

6 Noise is the second most deadly pollutant in western Europe Tinnitus Cognitive Impairment Annoyance Sleep Disturbance Cardiovascular Disease At least one million healthy life years are lost every year from traffic related noise in the western part of Europe Burden of disease from environmental noise - World Health Organization 2011 The EU noise policy after the second round of noise maps and action plans - Paviotti et al 2013

7 NVH: many sources of different nature Aerodynamic Engine Exhaust Transmitted Vibrations Road

8 Challenge Importance NVH Intelligent Designed Materials

9 Challenge Novel Material Concepts Importance NVH Intelligent Designed Materials Design Tools Adequate Characterisation

10 Novel Material Concepts Single layer systems not capable to reach weight-nvh target Trigger mechanisms that lead to improved NVH 1. Viscothermal damping 2. Coupling propagating to (highly) damped wave types 3. Wave interference 4. Resonance mechanisms... intelligently tailored to reach specific functionality

11 Novel Material Concepts: 1. Viscothermal damping Micro perforated panels Atalla N., Sgard F., Modeling of perforated plates and screens using rigid frame porous models Journal of Sound and Vibration, 303 (1-2): , (2007)

12 Novel Material Concepts: 2. Coupling to (highly) damped wave types Combination of different layers: Mulitlayer systems Elastic Visco-elastic Poro-elastic Air different properties, different wave types Allard J., Atalla N. Propagation of Sound in Porous Media: Modelling Sound Absorbing Materials, Wiley, Chapter 5, Chapter 11 (2009)

13 Novel Material Concepts: 3. Wave interference Periodic grid of scatterers leads to destructive interference and thus wave cancellation Sánchez-Pérez J., Caballero D., Martinez-Sala R., Rubio C., Sánchez-Dehesa J., Meseguer F., Llinares J. and Gálvez F. Sound attenuation by a two-dimensional array of rigid cylinders. Physical Review Letters, 80(24):5325 (1998).

14 Novel Material Concepts: 4. Resonance mechanisms Resonant Inclusions Claeys, C., Sas, P., Desmet, W. (2014). On the acoustic radiation efficiency of local resonance based stop band materials. Journal of Sound and Vibration, 333 (14),

15 Design tools Expensive full models... Multiphysics Combination of length scales Modelling of bonding Propagation direction Can be preceded by affordable indacative models Unit-Cell models Transfer Matrix Models

16 Adequate characterization Laboratory characterisation often don t comprise the complete physics at hand In situ measurements are costly and difficult to validate numerically

17 Adequate characterisation: KU Leuven Soundbox Representative non standardised test set-up allows characterisation of materials and numerical validation

18 Acoustic Resonant Meta-materials

19 Acoustic resonant metamaterials (audio)

20 Metamaterials with stop band behaviour What How Apply

21 Stop band behaviour... certain frequency zones do not propagate f 1 f 2 f 3

22 Tuned Vibration Absorbers Mass Damped Spring Resonance Frequency

23 Power of metamaterials - example Localised input force Study average (RMS) displacement of plates under addition of tuned vibration absorbers (TVAs)

24 Power of metamaterials - example Case 1 and 2: Same mass addition!

25 +20% mass (local) +20% mass (spread) Target Average Displacement [db] Frequency [Hz]

26 Power of metamaterials example 2 Larger plate More input forces 2% added mass Study effect of number of TVAs

27 Power of metamaterials example 2

28 Power of metamaterials example 2

29 Power of metamaterials example 2

30 Power of metamaterials example 2 1 TVA 240 TVAs

31 1 TVA 40 TVAs 240 TVAs Target Stop Band

32 Metamaterials: resonant additions... on a subwavelength scale

33 What How Apply Blocked Frequency Zones Resonant Additions

34 Unit Cell Definition Unit Cell

35 Unit Cell Modelling 1. Make model of the unit cell 2. Find wave solution of the unit cell 3. Derive motion of infinite structure

36 Unit Cell Modelling Mass ratio Stop Band Propagation Direction Resonance frequency

37 Unit Cell Modelling what to remember Unit cell modelling allows quick estimation of stop bands, deriving driving parameters, fine-tuning of design in late stage. Stop bands are due to resonant additions, related to effective added mass, driven by resonance of additions.

38 Claeys, C. C., Vergote, K., Sas, P., & Desmet, W. (2012). On the potential of tuned resonators to obtain lowfrequency vibrational stop bands in periodic panels. Journal of Sound and Vibration. x 20 x 12 1 TVA 40 TVAs 240 TVAs Propagation Direction Propagation Direction

39 Stop Band Prediction Unit cell modelling Infinite periodic structure Propagation direction Dispersion diagrams

40 Stop Band Prediction Unit cell modelling Propagation direction Finite structure modelling Claeys, C. C., Sas, P., & Desmet, W. (Under Review). On the acoustic radiation efficiency of local resonance based stop band materials. Journal of Sound and Vibration.

41 What How Apply Blocked Frequency Zones Unit Cell Models Resonant Additions Driving Parameters

42 Application: lightweight structures... Cover layer (Hollow) Core... good weight/stiffness, worse vibro-acoustic behaviour

43 Practical Realisation

44 Claeys, C., Vivolo, M., Sas, P., & Desmet, W. (2012). Study of honeycomb panels with local cell resonators to obtain low-frequency vibrational stopbands. Dynacomp 2012

45 Claeys, C., Vivolo, M., Sas, P., & Desmet, W. (2012). Study of honeycomb panels with local cell resonators to obtain low-frequency vibrational stopbands. Dynacomp 2012 Structural Proto-type D C B A

46 Structural Proto-type

47 Decoupled Design Stiffness Vibration Reduction Isolation Lightweight Structures

48 Resonant inclusion Mass Mass Spring Spring

49 12.5 mm 12.5 mm

50 Metamaterial concept Resonant Inclusions

51 Metamaterial demonstrator Intelligent material use 15 db additional noise reduction, no added weight

52 Numerical and experimental analyses Less resonators Less wide/strong reduction Non periodic No effect Different shape No effect Different resonator Shift in stop band Combination of resonators Multiple smaller bands Skin orientation No effect

53 Versatile concept Resonant structure Hosting structure Cover layer

54 Compact Sound Isolation Light Metamaterials Easy to Design

55 Some references Atak, O., Huybrechs, D., Pluymers, B., Desmet, W. (2014). The design of Helmholtz resonator based acoustic lenses by using the symmetric Multi-Level Wave Based Method and genetic algorithms. Journal of Sound and Vibration, 333 (15), Claeys, C., Sas, P., Desmet, W. (2014). On the acoustic radiation efficiency of local resonance based stop band materials. Journal of Sound and Vibration, 333 (14), Deckers, E., Jonckheere, S., Vandepitte, D., Desmet, W. (2014). Modelling techniques for vibro-acoustic dynamics of poroelastic materials. Archives of Computational Methods in Engineering. Atak, O., Bergen, B., Huybrechs, D., Pluymers, B., Desmet, W. (2014). Coupling of Boundary Element and Wave Based Methods for the efficient solution of complex multiple scattering problems. Journal of Computational Physics, 258, D'Amico, R., Huybrechs, D., Desmet, W. (2014). A refined use of the residue theorem for the evaluation of band-averaged input power into linear second-order dynamic systems. Journal of Sound and Vibration, 333 (6), Claeys, C., Vergote, K., Sas, P., Desmet, W. (2013). On the potential of tuned resonators to obtain low-frequency vibrational stop bands in periodic panels. Journal of Sound and Vibration, 332 (6), Deckers, E., Vandepitte, D., Desmet, W. (2013). A Wave Based Method for the axisymmetric dynamic analysis of acoustic and poroelastic problems. Computer Methods in Applied Mechanics and Engineering, 257, Jonckheere, S., Deckers, E., Van Genechten, B., Vandepitte, D., Desmet, W. (2013). A direct hybrid Finite Element - Wave Based Method for the steady-state analysis of acoustic cavities with poro-elastic damping layers using the coupled Helmholtz- Biot equations. Computer Methods in Applied Mechanics and Engineering, 263,

56 Some references D'Ortona, V., Vivolo, M., Pluymers, B., Vandepitte, D., Desmet, W. (2014). Experimental identification of noise reduction properties of honeycomb panels using a small cabin. TRA transport research arena. Paris, April 2014 (art.nr ). Claeys, C., Sas, P., Desmet, W. (2013). On the radiation efficiency of local resonance stop bands. Proceedings of MEDYNA 2013, 1st Euro-Mediterranean Conference on Structural Dynamics and Vibroacoustics.. MEDYNA Marrakech (Morocco), April Vivolo, M., Pluymers, B., Vandepitte, D., Desmet, W. (2013). Normal-incidence sound absorption measurements by means of a small cabin.. AIA-DAGA Meran, March Belgio. Jonckheere, S., Vandepitte, D., Desmet, W. (2013). Efficient analysis of trimmed cavities with a hybrid (u,p) Finite Element Wave Based Method'. AIA-DAGA. Merano (Italy), March Deckers, E., Vandepitte, D., Desmet, W. (2013). A Trefftz based prediction technique for the dynamic response of poroelastic media in vibro-acoustic applications. Proceedings of the 5th BIOT conference on Poromechanics (BIOT-5). Buit-5. Vienna (Austria), July. Vivolo, M., Van Genechten, B., Pluymers, B., Vandepitte, D., Desmet, W., Malkoun, A., Keppens, T. (2012). Vibro-acoustic design optimisation of a composite sandwich panel using a new experimental setup. DYNACOMP First International Conference on Composites Dynamics. Dynacomp. Arcachon, May 2012 (art.nr. 35). Van der Kelen, C., Vivolo, M., Van Genechten, B., Pluymers, B., Desmet, W., Malkoun, A., Bergen, B., Keppens, T. (2012). Validation of a Finite Element model by experiments of a dedicated test set-up for boundary excitation of trim assemblies.. ISMA. Leuven, September 2012.

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