Directivity Driven Simulation Methodology for Efficient Acoustic Encapsulation

<div class="section abstract"><div class="htmlview paragraph">Noise reduction at the source level is key to achieve the overall vehicle level interior targets. This paper presents a novel approach that integrates directivity analysis with simulation techniques to optimize acoustic encapsulation design for automotive sound sources to achieve the targeted radiation levels. The foundation for this methodology is to measure the angular distribution of sound pressure levels around the noise source so called Directivity, at every frequency of interest and determine the most effective acoustic encapsulation to achieve the targeted sound radiation. Accurate measurement of directivity in physical testing with fine angular resolutions can be complex and expensive, this study utilizes numerical simulation techniques using FEA to mitigate the challenges in mid frequency range. The scope of the study is focused on mid frequency sound pressure levels between 500-2500 Hz, which are determined to be significant contributors to overall DU noise. The first step is to determine the sound radiation levels of DU for various Motor and Gear Loads in free field and establish Sound radiation of the system. Subsequently, the research identifies the optimized encapsulation configurations that minimize sound pressure levels across multiple planes of directivity angles by conducting a DOE on encapsulation parameters—such as material composition, layer thickness, and distance from the noise source. Spatial packaging constraints are considered in this study to establish a feasible design volume. The scope also provides the direction to map the entire design volume with dominant composition of treatments to achieve the target. The selected designs are then realized as packaging feasible prototypes of the encapsulation and then be physically tested for comparative analysis between encapsulated and non-encapsulated drive trains. The effectiveness of the proposed noise control strategy is validated through a comparison of noise reduction results obtained from physical testing and simulation. This method provides a cost-effective approach to achieve overall noise reduction targets in automotive applications. And it enables the precise targeting of noise attenuation in a critical frequency range by enhancing acoustic encapsulation performance in future automotive designs. This directivity-based strategy can be expanded further to understand the mechanism of any source to effectively design the system to enhance the acoustic performance.</div></div>