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The paper focuses on the numerical investigation of riding comfort of an agricultural vehicle. The analysis is carried out combining a multi-body model of a tractor with a tire-soil interaction model. The multi-body model schematizes the tractor through several rigid bodies representing the chassis, the cabin, the seat and the tires. Model parameters (masses, suspension parameters) were identified by means of full scale tests on a four-post test-rig. Tire-soil interaction model allows computation of the forces exchanged at the contact interface considering soil deformability and the 3D tread design. Several simulations were performed considering the vehicle running at constant speed over a deformable soil; different combinations of suspensions parameters were analyzed to determine their effect on driver comfort evaluated in terms of vertical acceleration on the seat. In addition, the analysis was completed with four different scenarios coupling two different tires with two different soils. [ABSTRACT FROM AUTHOR]

Abstract: The effects induced on handling of a high sided vehicle by a variation of cross wind aerodynamic forces caused by the crossing of the wake of a bridge tower are studied using an experimental–numerical approach. The proposed model aims at simulating the interaction between the aerodynamic forces and moments and the vehicle–driver behavior. The aerodynamic forces, instantaneously acting on the vehicle, are computed according to a quasi-static force distribution approach that relies on wind tunnel tests performed on still scaled models. Time domain simulations of the vehicle–driver response to cross wind forces are performed to investigate the safety of the bridge traffic in presence of tower wake crossing, taking into account the risk of lane changing and/or vehicle rollover. In particular an analysis of the vehicle–driver system response, for a reference bridge situation, in presence and absence of wind fences near the tower, is performed to evaluate their effectiveness. [Copyright &y& Elsevier]

Abstract: In the recent years, rollover has become an important safety issue for a large class of vehicles. Even though rollovers constitute a small percentage of all accidents, they have unproportionally large contribution to severe and fatal injuries. Under this point of view, rollover of heavy vehicles is particularly critical being associated with large traffic disruption, economic loss and risks connected to the transported goods. One of the main causes for heavy vehicles rollover is recognised to be cross wind. In order to determine which parameters (geometry and vehicle type, infrastructure scenario, turbulence conditions, etc.) most affect the aerodynamic loads acting on heavy vehicles, a comprehensive experimental campaign has been carried out in the Politecnico di Milano wind tunnel. The overall activity is presented in 2 papers. In this first paper attention is focused on a high-sided lorry in flat ground scenario. Mean aerodynamic forces and moments have been measured by means of a six-components dynamometric balance for different yaw angles and turbulence conditions. Moreover, in order to gain an insight of the flow pattern around the vehicle, pressure distribution on the vehicle surface has been measured. Finally, the vehicle aerodynamic admittance function has been assessed, for high turbulence conditions, to investigate the unsteady force/moment component. The second paper deals with the effect of infrastructure scenario (flat ground, embankment, double and single viaduct), of position (vehicle placed upwind or downwind) and of vehicle geometry/type (high-sided lorry with and without a trailed unit, tractor-semitrailer combination and tank truck) on the aerodynamic forces and moments, including both steady and unsteady components. [Copyright &y& Elsevier]

Abstract: The sensitivity of heavy road vehicle aerodynamic coefficients to different testing parameters (scenario, vehicle type and turbulence intensity) is experimentally evaluated in this paper through wind tunnel experiments. The first part of the paper has investigated the aerodynamic loads (both stationary and non-stationary) acting on a high-sided lorry (VAN) in a flat ground scenario. The mean aerodynamic coefficients, the flow pattern around the vehicle and the aerodynamic admittance function have been assessed and compared for different wind turbulence conditions (boundary layer simulations). The present paper instead investigates the influence of the infrastructure scenario (flat ground, embankment, single and double viaduct), of the exposition (upwind or downwind) and of a trailed unit on the aerodynamic loads acting on the vehicle. Moreover, the mean aerodynamic coefficients and the aerodynamic admittance function of the high-sided lorry considered in the first part are compared with the ones of other heavy vehicles (tank truck, tractor–semitrailer combination and tractor–trailer combination) to assess the influence of the vehicle geometry. [Copyright &y& Elsevier]

Abstract: This paper examines the wind induced forces and moments experienced by a high sided lorry. Full-scale measurements are combined with wind tunnel and CFD simulations in order to gain an insight into the flow field around the vehicle. Differences and similarities between the three techniques are noted. It is shown that the rolling moment coefficient obtained from full-scale measurements and CFD simulations agree consistently across a wide range of yaw angles. With respect to the side force coefficient, good agreement between the wind tunnel and full-scale data are achieved. Pressure distributions over selected sections of the lorry reveal that despite good agreement with the overall forces, the localised pressure field can be significantly different. [Copyright &y& Elsevier]