The vibrations transmitted to the driver are dangerous to his safety because they can cause temporary and permanent injuries to the body. Tractors are characterized by vibrations with high intensity and low frequency that increase the difficulties in the design of solutions able to reduce vibration transmissibility to the driver. The new suspension systems diffused in recent years have been designed to reduce the vertical acceleration, despite the fact that numerous studies have highlighted how the most critical directions are represented by the horizontal ones. This is caused by the angular accelerations, amplified in modern tractors with high dimensions, by the high distance from the seat and the tractor rolling axis. Despite manufacturers’ efforts in the last decade, the level of the vibration transmitted to the driver in different tasks exceeds the exposure levels established by the standards. The goal of the paper is to evaluate the influence of each vehicle’s rigid motion (pitch, roll and bounce) on the vibration level transmitted to the driver in a tractor of about 170 kW power with axle suspension, cab and seat suspension. Two inertial measuring units have been fitted on the cab and frame of a tractor to measure the roll angular velocity and the bounce motion respectively of the cab and frame. A triaxial accelerometer has been fitted on the driver seat to measure the driver acceleration. The tractor has been used in different working conditions to evaluate the influence of the mass distribution on each rigid motion and with different driving velocities. The power spectrum densities have been analyzed to evaluate the predominant frequencies for each mode. These tests have permitted a better comprehension of the whole body’s vibrations caused by a tractor. In particular, the distribution of the acceleration on the three axis has been defined with respect to different working conditions. In the on road transport the longitudinal acceleration is prevalent. The vibration level on the road is more influenced by the pitch and the bounce. The suspension systems and, in particular, the front axle suspensions are able to reduce the pitch of the tractor, but do not reduce the bounce due to the absence of the rear suspensions.
G. Molari, M. Mattetti, M. Badodi, E. Sedoni (2012). Vehicle rigid motion effects on whole body vibration. VALENCIA : Geyseco.
Vehicle rigid motion effects on whole body vibration
MOLARI, GIOVANNI;MATTETTI, MICHELE;BADODI, MATTEO;
2012
Abstract
The vibrations transmitted to the driver are dangerous to his safety because they can cause temporary and permanent injuries to the body. Tractors are characterized by vibrations with high intensity and low frequency that increase the difficulties in the design of solutions able to reduce vibration transmissibility to the driver. The new suspension systems diffused in recent years have been designed to reduce the vertical acceleration, despite the fact that numerous studies have highlighted how the most critical directions are represented by the horizontal ones. This is caused by the angular accelerations, amplified in modern tractors with high dimensions, by the high distance from the seat and the tractor rolling axis. Despite manufacturers’ efforts in the last decade, the level of the vibration transmitted to the driver in different tasks exceeds the exposure levels established by the standards. The goal of the paper is to evaluate the influence of each vehicle’s rigid motion (pitch, roll and bounce) on the vibration level transmitted to the driver in a tractor of about 170 kW power with axle suspension, cab and seat suspension. Two inertial measuring units have been fitted on the cab and frame of a tractor to measure the roll angular velocity and the bounce motion respectively of the cab and frame. A triaxial accelerometer has been fitted on the driver seat to measure the driver acceleration. The tractor has been used in different working conditions to evaluate the influence of the mass distribution on each rigid motion and with different driving velocities. The power spectrum densities have been analyzed to evaluate the predominant frequencies for each mode. These tests have permitted a better comprehension of the whole body’s vibrations caused by a tractor. In particular, the distribution of the acceleration on the three axis has been defined with respect to different working conditions. In the on road transport the longitudinal acceleration is prevalent. The vibration level on the road is more influenced by the pitch and the bounce. The suspension systems and, in particular, the front axle suspensions are able to reduce the pitch of the tractor, but do not reduce the bounce due to the absence of the rear suspensions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
