Commercial Vehicle Comfort under Human Vibration Perspective

This paper discusses the importance of vibration transmitted from the ground to the driver from the perspective of human whole-body vibration (WBV). The scope of analysis is to compare the main vehicle frequencies with those important from the human vibration health and comfort point of view. That was performed by mapping the vibration transmissibility present in different sub sections of the vehicle. The first is the transmissibility between the axles and the chassis rail, the following between the chassis rail and the cabin. The last would be between the cabin and the drivers' seat, although that was not possible from the acquisition point of view. The vehicles measured have mechanical suspension and elastomeric cabin coupling. It is known that all suspension systems in vehicle are highly nonlinear, although here linear dynamic analysis methods were used. The methodology of analysis was based on empirical tuning procedure to improve comfort sensation on a 13T 4X2 straight truck prototype. When comparing the measurements results it was verified that great differences in comfort behavior is reached when modifying the simplest rubber parameter of the cab suspension. Such comfort behavior is closely related with the primary suspension parameters (stiffness and damping), tires parameters and an efficient seat suspension. However for high frequencies there is a favorable result to new proposals with tuned rubber thickness and stiffness, represent by reduced transmissibility and consequently an increase on admissible driving journey according to the ISO 2631-1. The outputs from this analysis were used as reference for the development of a new truck project.