Speaker
Description
In mechanical engineering, structural vibrations are one of the primary causes of sound radiation. Given the growing demands for environmental protection, Noise, Vibration, and Harshness (NVH) analysis has emerged as a distinct engineering discipline in recent years. To address these NVH challenges, simulations are typically employed, following a structured process generally divided into three sequential steps:1) Structural analysis,2) Dynamic analysis, and 3) Acoustic analysis.The structural analysis is considered state of the art. For the dynamic analysis, flexible multibody simulations have demonstrated their effectiveness as a tool for predicting structural vibrations. These simulations provide the boundary conditions for the acoustic analysis, directly in the time domain. To cut down computational complexity, reduced flexible bodies are often used, allowing industrial applications to be computed in acceptable times.Acoustic analyses are typically performed in the frequency domain, however, for transient signals, transformations are required, which can introduce challenges such as leakage effects. Direct calculation of sound radiation in the time domain is potentially advantageous but either computationally expensive under specific formulations or not yet sufficiently explored for practical applications.The Boundary Element Method (BEM) is particularly attractive for acoustic problems in NVH analysis, as it only requires discretizing the boundary of the vibrating structure, reducing complexity and making the method appealing to small and medium-sized enterprises. Galerkin formulations provide numerical stability but are associated with significantly high computational costs, limiting their practical applicability.This underscores the importance of our research, which focuses on the further development of a stable boundary integral formulation using the hypersingular boundary integral operator. The formulation leads to a space-time representation, where a specific chosen set of basis and test functions results in a system of equations with a triangular Galerkin matrix that can be efficiently solved via a time-stepping procedure.To minimize the computational effort for large models and long-term simulations in practical applications, the operators are projected onto a reduced problem. The reduced basis, which can be interpreted as acoustic mode shapes, is determined using Proper Orthogonal Decomposition (POD). This approach proves to be especially effective in combination with reduced flexible multi-body simulations, where structural vibrations and, consequently, the Neumann data for the acoustic calculations are affine-linear. Preliminary investigations on practical test cases reveal a substantial reduction in computational effort with negligible errors, establishing this approach as exceptionally efficient for industrial applications.
