Overview

This document summarizes the key academic publications focusing on automotive acoustics, NVH (Noise, Vibration, and Harshness), and lightweight material engineering. The research spans active noise control, poroelastic materials, vibroacoustic simulations, and weight reduction strategies for automotive applications.

PhD Thesis

Title: Method for Calculating Aircraft Noise in Dwellings

  • University: Université du Mans, France
  • Year: 2002
  • Supervisor: Jean Hardy
  • Laboratory: Laboratoire d’Acoustique de l’Université du Mans
  • Summary:
    • Developed a novel method (GRIM) to calculate aircraft noise inside dwellings, not just outdoors.
    • Combined a geometric approach for outdoor sound propagation with a modal approach for modeling rooms, windows, and balconies.
    • Achieved predictive accuracy for single-glazed windows, validated by in-situ measurements and laser velocimetry in the lab.
    • Highlighted the critical impact of incident wave directivity on the acoustic insulation of glazing, especially for grazing waves (e.g., from aircraft).
    • Identified limitations of the uncoupled double-plate modal model for double-glazed windows, suggesting alternative approaches for façade elements.
  • Impact:
    • Advanced understanding of sound transmission through building facades.
    • Provided a foundation for further research on environmental noise control and acoustic insulation.

Key Research Themes

1. Active Noise Control (ANC) in Vehicle Interiors

Efficiency of Active Noise Control Systems in Car Interiors

  • Summary: Investigates the spatial matching of primary and secondary sound fields to ensure efficient global noise control in vehicle cabins.
    • Emphasizes the importance of modal properties of cavities in defining optimal loudspeaker and microphone positions.
    • Contributes to personalized audio zones in modern vehicle cockpits.
  • Impact: Enhances passenger comfort by optimizing ANC system performance.

2. Vibroacoustic Simulations and Poroelastic Materials

Vibroacoustic Simulations of Automotive Trim Parts

  • Summary: Addresses the challenge of simulating poroelastic materials (foams, felts, textiles) in curved automotive components (dashboards, carpets, headliners).
    • Uses Finite Transfer Matrix Method (FTMM) for fast and reliable ranking of acoustic treatments.
    • Accounts for curvature effects from both vehicle structure and part shape.
  • Impact: Enables lightweight acoustic solutions while maintaining passenger comfort.

Broadening Low-Frequency Absorption Properties

  • Summary: Explores the use of resonators (Helmholtz, resonant membranes) and double-porosity materials to improve low-frequency sound absorption.
    • Focuses on macro-perforated porous media with micro/macro pore scales.
  • Impact: Extends the absorption range of lightweight acoustic treatments.

3. Weight Reduction and Optimization Strategies

Weight Reduction Strategies for Acoustic Treatments

  • Summary: Develops lightweight noise treatment technologies to meet CO₂ emission targets without compromising acoustic comfort.
    • Uses BEM/FEM approaches for low-to-mid frequency simulations.
    • Achieves significant weight reductions (e.g., <2500 g/m² for insulators).
  • Impact: Balances acoustic performance, weight, and cost for automotive applications.

Generalized Light-Weight Concept for Soundproofing

  • Summary: Introduces a multi-layer lightweight concept with tunable absorption properties.
    • Optimized using 2D Transfer Matrix Method (TMM).
    • Combines insulation and broadband absorption in a single solution.
  • Impact: Adopted for underbody shields and interior panels in production vehicles.

4. Acoustic Synthesis and Modeling Methods

Vehicle Acoustic Synthesis Method (VASM)

  • Summary: Links OEM acoustic targets to optimized acoustic package design using an energy-based approach.
    • Calculates Sound Pressure Levels (SPL) at ear positions from sound power measurements.
    • Validates the use of p-u probes (pressure-velocity) for sound intensity and transfer function measurements.
  • Impact: Bridges the gap between acoustic performance targets and practical design solutions.

Integration of Curved Trims in SEA Models

  • Summary: Determines Damping Loss Factors (DLF) and Coupling Loss Factors (CLF) for curved trims in Statistical Energy Analysis (SEA) models.
    • Improves prediction of radiation efficiency for complex shapes.
  • Impact: Enhances the accuracy of SEA models for fully trimmed vehicles.

5. Tire Noise and Environmental Acoustics

Tire Noise Radiation (GRIM Method)

  • Summary: Develops a mixed integral/ray-tracing method to compute tire noise radiation.
    • Accounts for multiple reflections and diffraction between tires, ground, and vehicle body.
  • Impact: Reduces tire noise contribution to overall vehicle NVH.

Sound Transmission in Buildings and Near Airports

  • Summary: Models sound transmission using a decoupled approach (integral, modal, and geometric methods).
    • Analyzes architectural effects (balconies, roofs) and meteorological conditions.
  • Impact: Supports urban planning and noise reduction near transportation infrastructure.

6. Experimental Measurements and Validation

Diffuse Field Absorption Coefficient Measurements

  • Summary: Uses reverberant chambers (e.g., Alpha Cabin) to measure absorption coefficients of flat and real-life parts (e.g., engine hoods).
    • Validates numerical models (SEA, ray-tracing) with experimental data.
  • Impact: Ensures reliability of acoustic simulations for industrial applications.

Research Impact

  • Publications: 33 (18,521 reads, 320 citations).
  • Collaborations: Faurecia, CSTB (Scientific and Technical Center for Building).
  • Industrial Applications:
    • Lightweight acoustic treatments for B-segment vehicles.
    • Optimized sound packages for improved Articulation Index (A.I.).
    • Innovative materials and processes for automotive NVH.

References

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