Steering system modal analysis

Abstract: The vehicle manufacturing sector is constantly evolving, and corporations are fully aware of increased consumer expectations for both driver and passenger´s comfort. SCANIA CV AB, as one of the largest Swedish manufacturers of commercial vehicles, has put an emphasis on this area. To guarantee these high-quality standards, several tests are conducted daily. Within this framework, this project aims to gain a better understanding of the phenomena associated with steering wheel vibrations. This project has an experimental focus on recreating sensitive driving conditions and addressing the vibration transfer paths to the main user interface such as the steering wheel. As widely known, the main problems related to vibrations come from resonance excitations. The most obvious solution would be to simply avoid matching any system´s eigenmodes with external excitations. Considering broadband excitations such as bumpy roads or engine vibrations, it is very unlikely that none of the critical frequencies is triggered. A better and more realistic idea would be minimizing the effects of these resonances by structural optimization. However, to do so, the eigenmodes should first be addressed. For this purpose, this project focused on identifying the annoying frequencies triggered while recreating sensitive driving scenarios. These sensitive scenarios were identified by Scania as circumstances in which the steering wheel feel gets altered. Specifically, it was decided to focus on road-induced vibrations, wheel-induced vibrations and engine-induced vibrations. The main findings show that during these tests, some resonances are triggered and interesting features are captured on the steering wheel.