Coupled Boundary Element and Poro-Elastic Material Simulation Approach to Designing Effective Acoustic Encapsulation for Vehicle Components

To meet vehicle interior noise targets and expectations, components including those related to electric vehicles (EVs) can effectively be treated at the source with an encapsulation approach, preventing acoustic and vibration sources from propagating through multiple paths into the vehicle interior. Encapsulation can be especially useful when dealing with tonal noise sources in EVs which are common for electrical components. These treatments involve materials that block noise and vibration at its source but add weight and cost to vehicles – optimization and ensuring the material used is minimized but efficient in reducing noise everywhere where it is applied is critically important. Testing is important to confirm source levels and verify performance of some proposed configurations, but ideal encapsulation treatments are complex and cannot be efficiently achieved by trial-and-error testing. Simulation is a key supporting tool to guide location, thickness, and properties of encapsulation acoustic treatments to meet targets with no excess cost or weight. Effective simulation accounts for mass, damping, and acoustic attenuation effects of the encapsulation with fine detail in all propagation directions and in a wide frequency range that corresponds to what will most affect an occupant, generally up to 10kHz. This paper presents an approach coupling a Boundary Element Method (BEM) approach to a poro-elastic material (PEM), representation of the encapsulation that accounts for all mass, damping, and acoustic attenuation effects on a base component structure modeled classically by a Finite Element Method (FEM). The modeling methods are described and representative comparisons of bare and encapsulated acoustic transmission are shown. Application recommendations are given and next steps to advanced use of the method are presented, which is suitable to characterize sources attenuated by encapsulation that can be used to simulate vehicle interior and exterior noise.