Adams Car Package > Adams Car > Appendix > Ride Height

Ride Height

 
For a linear spring
For a nonlinear spring
For an air spring
When you select the spring install method Ride Height, you directly specify what the ride height of the vehicle should be, along with a measurement of the current ride height. The target ride height is achieved during static equilibrium. In subsequent transient analyses, the ride height remains fixed.
 
Note:  
If your target ride height is relatively far from the design position, Adams Solver may have difficulty finding static equilibrium.

For a linear spring

Linear springs normally use the Adams Solver SPRINGDAMPER Statement to calculate the spring force. However, this force element is not compatible with the ride height method. In this case, the linear spring uses an Adams Solver SFORCE statement as follows:
DiffEQ = IF(MODE-5: 0, -1000 * (RideHeightMeasure - DesiredRideHeight), 0)
OffsetCal = DIF(DiffEQ) + FreeLength
Spring Force = ScaleFactor * K * (OffsetCalc - DM(I,J))

For a nonlinear spring

For nonlinear springs, the force in your template-based product is expressed using the Akima spline interpolation of a force versus spring deflection or spring length. The Adams Solver SFORCE statement calculates the nonlinear spring force as follows:
DiffEQ = IF(MODE-5: 0, -1000 * (RideHeightMeasure - DesiredRideHeight), 0)
OffsetCalc = DIF(DiffEQ)
■When using a force versus deflection characteristic:
Spring Force = ScaleFactor * AKISPL(OffsetCalc - DM(I, J), 0, Spline)
■When using a force versus length characteristic:
Spring Force = ScaleFactor * AKISPL(OffsetCalc + DM(I, J), 0, Spline)

For an air spring

For airsprings, the force in your template-based product is expressed using the three-dimensional Akima spline interpolation of a force versus trim load and deflection from trim length.
An Adams Solver SFORCE computes the air-spring force. The SFORCE function is
DiffEQ = IF(MODE-5: 0, -1000 * (RideHeightMeasure - DesiredRideHeight), 0)
OffsetCalc = DIF(DiffEQ)
force = ScaleFactor * AKSIPL((OffsetCalc – DM (marker I, marker j)), (trimLoad), splineID)