Frequency Based Substructuring as Key Enabler for New NVH Root Cause Analysis Types in FE Simulations

Noise, vibration, and harshness (NVH) performance is critical in the automotive development process, yet identifying the true root causes of unwanted dynamic behavior remains a challenge in full vehicle or system‑level finite element (FEM) models. This work demonstrates how frequency based substructuring (FBS) provides an efficient framework for understanding NVH and facilitates new root cause analysis types and processes. To begin, we prove the high numerical accuracy of the FBS algorithm deployed in the BETA CAE software by comparing its results with those obtained without substructuring. Then we illustrate how FBS supports new root cause analysis types, starting with a new variant of transfer path analysis (TPA). While standard TPA assesses the paths between only two system components, the new expanding TPA is a multi-step process that identifies the most critical path across all components in a fully automated way. Furthermore, if the FBS workflow starts with a modal representation of the components rather than their frequency response functions (FRF), a different class of root cause analysis type becomes possible. We introduce a second new analysis type named modal influence (MI) that reveals the effect of the modes of any component on a certain response. Its key characteristic is that MI analysis is not restricted to the response component opposite to the well-known modal participation factors. Finally, we demonstrate how we combine the FBS workflow with other established analysis types like equivalent radiated power (ERP) or exterior acoustic pressure analysis in an effortless manner. This way these calculation types also benefit from the various advantages of the FBS approach. Overall, this work positions the presented FBS workflow as a key enabler for efficient NVH root cause analysis, highlighting that it offers cutting-edge tools and processes for NVH engineers.