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11th Annual COE Graduate Poster Presentation Competition

Design and Development of Multifunctional Micro-Porous Material for Acoustic Noise Mitigation

Student(s): Bharath Kenchappa (Ph.D.)

Advisor(s): Dr. Kunigal Shivakumar

Cross-Disciplinary Research Area: Multiscale Materials Development & Analysis

Background

Types of Porous Sound Absorbing Materials

Problem Definition

Challenges

  • Better noise management relative to current technology.

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  • UAM vehicles have limited real estate for specialized technology such as heat exchangers and acoustic liners necessitating the use of multifunctional materials, structures and coatings.

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  • Optimized sound absorption (>0.5) and transmission loss (> 20 dB) in the focused frequency range of 800 to 1,200 Hz.

A porous absorbing material is a solid that contains cavities, channels or interstices so that sound waves can enter through them. Porous absorbing materials can be classified as cellular, fibrous or granular; this is based on their microscopic configurations[1].

Current Technology

Acoustic Models and Flow Properties

Experimental / Analytical / Combined

Flow Properties

Typical granular material porosity

Static airflow resistivity

Tortuosity

Viscous and thermal characteristic lengths

MATELYS AlphaCell Simulator

  • Most transportation vehicle frequency range – 800 to 1,200 Hz (Focused range)

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  • Test is conducted : 250 to 1,600 Hz
  • The main objective of this work is to develop a lightweight acoustic liner material that has superior acoustic absorption and transmission loss by energy dissipation in multidirections.

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  1. To develop a novel method of fabricating a new micro-porous material using loose granules.

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  • To assess and validate the flow properties prediction method by experiment.

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  • Design, develop and validate a graded micro-porous material that has optimum sound absorption and transmission loss.

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Specific Objectives

Absorption Coefficient and Transmission Loss of Single Layer

Multilayer Micro-Porous Material

Test Methodology – Impedance Tube Test

Processing of Micro-Porous Material

Objectives

Results and Discussions

Absorption Coefficient and Transmission Loss of Multilayer

L50, M25, S25

Concluding Remarks

References

[1] M.J. Crocker and J.P. Arenas, Use of Sound-Absorbing Materials. In: Handbook of Noise and Vibration Control. New York: Wiley, (2007), 696–713.

[2] ASTM E150 – 12 Standard Test Method for Impedance and Absorption of Acoustical Materials Using a Tube, Two Microphones and a Digital Frequency Analysis System.

[3] ASTM E2611 – 09 Standard Test Method for Measurement of Normal Incidence Sound Transmission of Acoustical Materials Based on the Transfer Matrix Method