Adams Car Package > Adams Car > Appendix > Solver Routines > Ride Height Auto-Adjustment (vehicles with coil springs)

Ride Height Auto-Adjustment (vehicles with coil springs)

For vehicles with front and rear coil springs, a ride-height adjustment CONSUB varies the effective free length of the springs (linear or nonlinear) to achieve the desired ride heights. This routine was written to address Design of Experiment analysis where spring parameters were factors in the experiment and the user wished to maintain constant ride height for each trial of the experiment.
You invoke a CONSUB by including the following in the dataset (.acf) file.
CONTROL/FUN = USER(1152,jpr_ary,des_f_rh,f_array,des_r_rh,r_array,tol,maxit) where
 
jpr_ary
ID of ARRAY element containing the necessary joint primitives, motions, SFORCE IDs to perform static equilibrium.
des_f_rh
Desired front ride height (mm)
f_array
Front ride height adjustment array (see below)
des_r_rh
Desired rear ride height (mm)
r_array
Rear ride height adjustment array (see below)
tol
(optional) Ride height tolerance (mm) Default is .05 mm
maxit
(optional) Maximum number of iterations. Default is 50 iterations.
The CONSUB iteratively modifies the front and rear spring lengths to achieve the desired ride heights.
 
Notes:  
■Ride height is calculated by comparing the difference in z height between wheel center markers attached to the body and wheel carrier.
■The CONSUB is compatible with coil springs only.
■Asymmetric free lengths will be made equal. There is no provision for separate left and right ride height targets.
■Asymmetric spring rates are not handled. The CONSUB will likely fail in this situation.
■Since this consub must be used with the front and rear springs simultaneously, it is only applicable for full-vehicle analysis.
 
Format of Ride Height adjustment arrays
ARRAY/aryid, NUM = lwc,lwc_b,rwc,rwc_b
, l_spring_type,l_spr_or_array_id, l_flen
, r_spring_type, r_spr_or_array_id, r_flen
where:
 
lwc
Left wheel center marker ID on wheel carrier
lwc_b
Left wheel center marker ID on body
rwc
Right wheel center marker ID on wheel carrier
rwc_b
Right wheel center marker ID on body
l_spring_type
Left Spring type (1=linear, 2=nonlinear)
l_spr_or_array_id
ID of left SPRINGDAMPER element for linear springs, or ARRAY element for nonlinear springs. For nonlinear springs, an array is used to control the offset length of the spring.
l_flen
Initial left free length of spring (for nonlinear springs, this is the offset length)
r_spring_type
Right spring type (1=linear, 2=nonlinear)
r_spr_or_array_id
ID of right SPRINGDAMPER element for linear springs, or ARRAY element for nonlinear springs. For nonlinear springs, an array is used to control the offset length of the spring.
r_flen
Initial right free length of spring (for nonlinear springs, this is the offset length)