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Lateral Dynamics
Published in Georg Rill, Abel Arrieta Castro, Road Vehicle Dynamics, 2020
Georg Rill, Abel Arrieta Castro
The roll angle of a vehicle during cornering depends on the roll stiffness of the axle and on the position of the roll center. Different axle layouts at the front and rear axle may result in different roll angles of the front and rear part of the chassis, Figure 9.17. A chassis with a significant torsional compliance would allow its front and rear parts to roll nearly independently. Then, the load transfer ΔFz from the inner to the outer wheels will be the same2 at both axles, if the front and rear parts have the same height of the center of gravity. On most passenger cars, the chassis is rather stiff, however. In this case, front and rear parts of the chassis are forced by an internal torque TT to an overall chassis roll angle. This torque affects the wheel loads and thus generates a different load transfer at the front and rear wheels, ΔFzF≠ΔFzR. Due to the degressive influence of the wheel load on longitudinal and lateral tire forces, the steering tendency of a vehicle can be affected.
Planar Kinematics of Rigid Bodies
Published in Asok Kumar Mallik, Amitabha Ghosh, Günter Dittrich, Kinematic Analysis and Synthesis of Mechanisms, 1994
Asok Kumar Mallik, Amitabha Ghosh, Günter Dittrich
Figure 2.12-5 shows schematically a planar approximation of the front suspension of an automobile. The roll center refers to the point about which the body of the automobile seems to rotate with respect to the road. Assuming no slip between the tires and the road, determine the location of the roll center.
System reliability as a surrogate measure of safety for horizontal curves: methodology and case studies
Published in Transportmetrica A: Transport Science, 2020
Rushdi Alsaleh, Tarek Sayed, Karim Ismail, Fahad AlRukaibi
Sensitivity analysis is conducted to investigate the impact of vehicle parameters on both the associated with vehicle rollover (as one mode of noncompliance) and system of three modes of noncompliance. According to Equation (29), the rollover threshold of a vehicle is impacted by several vehicle parameters including (1) the ratio of the height of vehicle roll center above the ground to the height of vehicle center of gravity above the ground (), (2) the ratio of the average half width between the centers of the left-hand and the right-hand wheels of a vehicle to the height of vehicle center of gravity above the ground (), and (3) the rolling rate of the vehicle (). Considering the diversity in passenger car and truck models, vehicle parameters vary over ranges of values. The center of gravity of a vehicle, especially for trucks, is affected by many factors including the type of the loaded material, the distribution of the loaded material over the truck container, the total height of the vehicle, among others. The roll rate of a vehicle depends on many factors including vehicle springs-characteristic (e.g. springs constant value), among others.
Twist beam development at an early design stage: Effect of suspension and body characteristics on rear suspension durability
Published in Mechanics Based Design of Structures and Machines, 2020
Guilherme Carneiro, Marco Túlio Anjos, Ernani Sales Palma
In Eqs. (2) and (3), df and dr are the front and rear wheel track. l, lf and lr are the wheel base and the front and rear longitudinal distances of the axes in relation to the center of gravity. Ws is the vehicle weight acting on the center of gravity. K∅f and K∅r are the front and rear axle stiffness. hs is the distance between the center of gravity and the vehicle roll axle and hf and hr are the front and rear roll center heights.
On the handling performance of a vehicle with different front-to-rear wheel torque distributions
Published in Vehicle System Dynamics, 2019
Basilio Lenzo, Francesco Bucchi, Aldo Sorniotti, Francesco Frendo
The lateral forces, , are assessed through the lateral force part of the Pacejka Magic Formula, PAC2002 [32], neglecting camber angle and other secondary effects: where B, C and E are constant parameters, D depends on the vertical tire force, , e.g. D = (μ is the tire-road friction coefficient and is a correction parameter) and and are curve translation parameters. The tire slip angles, , are computed with classical in-plane kinematics [33]: where is the static toe of each wheel, experimentally measured, and the relationship is known for the tested vehicle (Figure 2). The vertical loads, , are assessed from the measured longitudinal and lateral accelerations of the vehicle center of mass, and : where g is the gravitational acceleration, and are the roll stiffness values of the front and rear suspensions, h is the center of mass height, is the i-th roll center height, d is the height of the intersection point between the roll axis and a y-z plane through the center of mass.