Experimental validations of the HELS method for reconstructing acoustic radiation from a complex vibrating structure

Area of Science:

• Acoustics
• Vibration analysis
• Computational mechanics

Background:

• Accurate reconstruction of acoustic pressure fields is crucial for understanding noise radiation from complex structures.
• Existing methods face challenges in reconstructing sound fields from limited or noisy measurements.
• The Helmholtz Equation Least Squares (HELS) method offers a potential solution for inverse acoustic problems.

Purpose of the Study:

• To experimentally validate the Helmholtz Equation Least Squares (HELS) method for reconstructing radiated acoustic pressures.
• To assess the HELS method's performance on a complex vibrating structure mimicking a vehicle front end.
• To investigate the influence of measurement parameters on reconstruction accuracy.

Main Methods:

• Experimental setup using a vehicle front-end structure with an internal loudspeaker for acoustic excitation.
• Measurement of radiated acoustic pressures over a planar surface above the structure.
• Application of the Helmholtz Equation Least Squares (HELS) method to reconstruct acoustic pressures on the structure's surface and in the surrounding field.

Main Results:

• Satisfactory reconstruction of acoustic pressures was achieved on the structure's top surface under both random and harmonic excitations.
• Reconstruction accuracy improved with an increased number of measurements and closer proximity to the source surface.
• The efficiency of the HELS method showed a tendency to decrease at higher excitation frequencies.

Conclusions:

• The HELS method is experimentally validated as an effective tool for reconstructing acoustic pressures from complex vibrating structures.
• Measurement strategy significantly impacts reconstruction accuracy, favoring denser and closer measurement arrays.
• High-frequency limitations are an inherent challenge for HELS, consistent with other wave expansion theories.