ADAMS - Problem 1 - Front view Geometry
Steps:
-First sla suspension is opened
-then original hard points table are compared with the given had points
-then parallel wheel travel analysis is performed
-then x variable is chosen which is wheel travel
-then y axis variable was chosen which is fvsa length
-then curve was plotted
-it showed that Fvsa length is 2914 mm
-then another y axis variable was chosen to plot the fvsa angle
-it showed that the angle was 5.21 degrees
Adams convention:
Calculation:
-Adams uses hypotentous as its swing arm while we the horizotal distance,inorder to convert between the two we will use the front view angle:
Triangle ABC:
Fvsa length(horizontal)(AB)=fvsl hypotenous(Ac)*cos(fvsa angle)=2914*cos(5.21)=2902mm
Camber gradient=arctan(1/fvsl(horizontal)(AB))= arctan(1/2902)=0.0197deg/mm
h=fvsa length*sin(fvsa)=2914*sin(5.21)=264.6 mm
H=wheel center height+h=300+264.6=564.6 mm
TRAINGLE CDE:
theta=arctan(H/fvsa length horizontal)=arctan(564.6/2902)=11 deg
Roll center height=0.5*tackwidth*tan(11)=0.5*1600*tan(11)=155.5 mm
Comparing to adams:
Adams roll center height is 154.3 (0.8% difference)
Adams camber gradient is 0.0196 deg/mm (0.5% difference)
|
Adams |
calculation |
Difference |
|
|
Roll center height |
154.3 |
155.5 |
0.8% |
|
Camber gradient |
0.0196 |
0.0197 |
0.5% |
The results show that there is minimal deviation compared to adams
Geometry sketch:
From the sketch: (As studied in theory)
Roll center height:138.843 mm
Fvsa length:3025 mm
Fvsa angle:9.846 deg
-Tuning the hard pints:
Tuned camber gradient curve:
New camber gradient of 0.022deg/mm
Tuned roll center location:
New roll center location 145 mm
Why lower front roll center?
-Lower roll center can be used to combat and reduce understeer in front heavy vehicle, as it will delay the loss of grip on that axle as it will reduce load transfer on that axle compared to the rear, so the rear axle will reach its limit first.
Files:
https://drive.google.com/drive/folders/1Feh2tiYDMtp8CRX_G4_R4KWGdbn6JcA1?usp=sharing