The ratio of suspension compression due to traction forces to the suspension extension due to weight transfer and axle torque. Anti-lift under acceleration is computed for the front suspension only, and only in a full-vehicle analysis. If the front suspension is not driven (fdrat = 0), the anti-lift will be 0.
Computed by:
SVCANA
Input Variables Used:
■Compliance matrix
■Average tire loaded radius
■Front drive ratio (fdrat)
■Front axle ratio (faxlr)
■Front suspension dependency (STRING/4)
■Total CG height
■Average wheelbase
■Track
Method:
SVC computes the longitudinal force due to acceleration:
Fleft = Fright = -fdrat / 2.0
and the vertical force due to weight transfer:
VWleft = VWright = -Total CG height / ( 2 wheelbase )
The driveshaft torque is:
Tdrive = Rl ABS( Fleft + Fright ) / faxlr
where Rl is the average loaded radius of the tire.
If the axle is dependent, the vertical force reaction at the wheel forces due to the driveshaft torque are:
VTleft = -Tdrive / Track
VTright = Tdrive / Track
If the axle is independent, VTleft = VTright = 0. The total vertical forces due to weight transfer and axle torque are:
Vleft = VWleft + VTleft
Vright = VWright + VTright
These are all forces at each wheel per unit total acceleration force.
Vertical deflections due to the vertical force are:
Zwleft = Vleft C( 3,3 ) + Vright C( 3,9 )
Zwright = Vleft C( 9,3 ) + Vright C( 9,9 )
Vertical deflections due to tractional forces are:
Zfleft = Fleft [C( 3,1 ) - Rl C( 3,5 )] + Fright [C( 3,7 ) - Rl C( 3,11 )]
Zfright = Fleft [C( 9,1 )-Rl C( 9,5 )]+Fright [C( 9,7 ) - Rl C( 9,11 )]
The percent anti-lift is:
Left percent anti-lift = -100. Zfleft / Zwleft
Right percent anti-lift = -100. Zfright / Zwright