List of Symbols

a distance front axle to c.g.; half of contact length
ax longitudinal acceleration
ay lateral acceleration
aμ slip velocity dependency coefficient for friction
Ar rolling resistance coefficient
b distance rear axle to c.g.; half contact width
B stiffness factor in ‘Magic Formula’
B1 brake force of rolling wheel
c stiffness; factor
cc lateral carcass stiffness per unit length
cgyr non-dimensional gyroscopic coefficient
cpx,y tread element stiffness per unit length of circumference
image tread element longitudinal stiffness per unit area
C cornering stiffness ; sum front and rear
Ci cornering stiffness, sum left and right
C contact centre (point of intersection)
C shape factor in ‘Magic Formula’
CdA air drag coefficient
CFx longitudinal stiffness of standing tyre
CFy lateral stiffness of standing tyre
CFz stiffness of tyre normal to the road
C cornering stiffness
C longitudinal slip stiffness
C camber stiffness for side force
C spin stiffness for side force
Cgyr tyre gyroscopic coefficient
C aligning torque stiffness
C camber stiffness for aligning torque
C spin stiffness for aligning torque
C torsional yaw stiffness of standing tyre
CMxγ overturning couple stiffness against camber
Ccx,y carcass horizontal stiffness of standing tyre
Cgyr gyroscopic coefficient
dfz normalised change in normal load, Eq.(4.E2a)
dpi normalised change in inflation pressure, Eq.(4.E2b)
dt tread depth
D peak factor in ‘Magic Formula’; dissipation function
E curvature factor in ‘Magic Formula’
e caster length; tread element deflection
f trail of c.g.; frequency [Hz]
fr rolling resistance coefficient
Fax force for forward acceleration
Fd air drag force
Fx,tot sum of longitudinal tyre forces
Fx longitudinal tyre force
Fy lateral tyre force
Fz vertical (normal) tyre force (load) (>0), in Chap.9, 10: Fz <0
Fr rolling resistance force (>0)
FN tyre normal force (>0)
FNo reference vertical load, nominal load (= |Fzo|)
FV tyre vertical force
FH tyre longitudinal horizontal force
g acceleration due to gravity; feedback rider control gain
G weighting factor
h height
H height; sharpness factor in ‘Magic Formula’
H transform; Hurwitz determinant
i image
iz radius of inertia
I moment of inertia
Iw wheel polar moment of inertia
Ip wheel polar moment of inertia
j image
k radius of inertia; viscous damping coefficient
K centrifugal force; force acting on belt, wheel centre
l wheel base
ls shift; two-point follower length
lb length of basic curve
lf offset
l unit vector along line of intersection
m mass; fraction of contact length 2a where adhesion occurs
mc contact patch mass
mt tyre mass
mm mass of mainframe (including lower part of rider)
mmr mass of mainframe plus rider
mr mass of upper torso
MB,D brake, drive torque
Mx overturning couple
My rolling resistance moment
Mz (self) aligning torque
image (self) aligning torque due to lateral deflections
image aligning torque due to longitudinal deflections
Mz,gyr gyroscopic couple
Mδ steer torque
n number of elements; frequency [Hz]
n unit vector normal to the road =(0,0,‒1)T
nst steer system ratio
p Laplace variable [1/m]
pi inflation pressure
q average vehicle yaw resistance arm; generalised coordinate
q contact force per unit length of circumference, vector
Q generalised force
r yaw rate; tyre (loaded) radius
rc radius of carcass (belt), unloaded; cross section crown radius
ryo free tyre radius varying along cross section contour, ryo = ryo(yco)
re effective rolling radius of freely rolling wheel
rf free unloaded tyre radius
rl loaded radius
ro free unloaded tyre radius (= Ro)
R radius of curvature
Ro free unloaded tyre radius (= ro)
s forward position of neutral steer point; half track width
s Laplace variable; travelled distance
ssx κ (practical longitudinal slip component)
ssy tanα (practical lateral slip component)
s unit vector along wheel spin axis
S wheel slip point; impulse; string tension force
SV,H vertical, horizontal shift
t pneumatic trail; time
tc caster length
tr rise time
t unit vector in road plane perpendicular to line of intersection l
T kinetic energy; moment acting on belt, wheel centre
u forward velocity of c.g.; longitudinal deflection
U potential energy
v lateral velocity of c.g.; lateral deflection
V speed of travel of c.g. (with x, y components)
V speed of travel of wheel centre (with x, y components)
Vc speed of contact centre C (with x, y components)
Vg speed of sliding (with x, y components)
Vo reference velocity =√(gRo)
Vr wheel linear speed of rolling (= VcxVsx)
Vs wheel slip velocity of slip point S (with x, y components)
Vx longitudinal speed component of wheel centre
image velocity of contact patch mass (with x, y components)
w vertical road (effective) profile (positive downwards)
W work
x,y,z longitudinal, lateral, vertical displacement
x,y,z coordinates with respect to moving axes system, z axis vertical
xo,yo,zo global coordinates
image global coordinates
X longitudinal horizontal tyre force
X,Y,Z global coordinates
yco distance from wheel centre plane
ymr lateral offset of mmr c.g.
α wheel (side) slip angle; axle (side) slip angle
α road transverse slope angle
image transient tyre slip angle
αa virtual axle slip angle
β vehicle side slip angle; tyre yaw torsion angle
βx,y road transverse, forward (effective) slope angle
βgyr gyroscopic wheel coupling coefficient, Eq.(6.35)
γ camber (wheel inclination) angle
image transient tyre camber angle
Γ unit step response function
δ steer angle of front wheels
δo l/R, steer angle at V→0
Δ increment
ε roll steer coefficient; rake angle of steering axis
ε string length ratio, Eq.(5.153); eff. roll. radius gradient ‒∂re/∂dt
ε small quantity to avoid singularity
εγ camber stiffness reduction factor
εNL non-lagging part
ζ damping ratio; spin factor (=1 if spin influence is disregarded)
ζh height ratio, Eq.(6.36)
ζα cornering stiffness load transfer coefficient
ζγ camber stiffness load transfer coefficient
η understeer coefficient; effective rolling radius gradient ‒∂re/∂ρz
ηy c.g. offset steer coefficient
θ tyre model parameter, Eqs.(3.6, 3.24, 3.46)
θ angular displacement about η axis; pitch angle
θc string model composite parameter, Eq.(5.160)
κ longitudinal wheel slip
image transient longitudinal tyre slip
κ damping coefficient due to tread width
λ wavelength; root characteristic equation
λ fraction of 2a where adhesion occurs; user scaling factor
μ coefficient of friction
ρ tyre radial (vertical) deflection
ρx,y,z tyre longitudinal, lateral, normal deflection
σ relaxation length; load transfer coefficient
σ theoretical slip, vector, Eq.(3.34)
σ intersection length in string model with tread elements
σc string model length parameter, Eq.(5.153)
σc contact patch relaxation length
τ roll camber coefficient
φ body roll angle; spin slip
image transient spin slip
φt turn slip
ϕ phase angle
ψ yaw angle; steer angle
ψc1 compliance steer angle
ψio toe angle
ω frequency [rad/s]
ωo undamped natural frequency
ω1,2 natural frequencies
ωn damped natural frequency
ωs path frequency [rad/m]
Ω wheel speed of revolution
ξ;,η,ζ moving axes system, η axis along spin axis, ξ; horizontal

Subscripts and superscripts

a axle; from belt to wheel rim centre
b belt; from belt centre to rim
c compliance (steer)
c contact patch; from contact patch centre to belt; crown; contour
D drag
e effective
eff effective (cornering stiffness)
eq equivalent
f free, unloaded; of front frame
g global
i 1: front, 2: rear
L,R left, right
m of mainframe
mr of mainframe plus rider
NL non-lagging
o original; initial; average; unloaded; nominal; at vanishing speed; natural
r roll; rolling; rolling resistance; of residual spring; of rider
s slip; from road surface to contact patch; of front sub-frame
sl at verge of total sliding
sf side force (steer)
ss steady state
st static
stw steering wheel
t transition from adhesion to sliding
w wheel
x,y,z forward (longitudinal), lateral (to the right), downward
zr residual (torque)
ξ;,η,ζ along, around ξ;,η,ζ axes
0 at zero condition
1,2 front, rear; leading, trailing edge
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