4569846498

Appendix B: Fortran tyre model subroutines 485
C -- As for longitudinal forces, Linear Decay to Sliding Friction
C above critical slip ratio --
C -- MU_S apparently not passed through? --
C FYFZ*(1-EXP(-Ay))*(MU-(ABS(ALPHA)ALPHA_C)/
ALPHA_M*(MUMU_S))
C FYFY*B*SIGN(1.0D0,ALPHA)
C -- Try U instead? --
FYFZ*(1-EXP(-Ay))*U*B*SIGN(1.0D0,ALPHA)
ENDIF
C C ********** FIALA CALCULATIONS **************
C C
C C Calculate critical value of slip angle
C C
C ASTARATAN(ABS(3.D0*U*FZ/CA))
C C
C C Compute Fiala lateral force and aligning torque (FY & TZ)
C C
C IF(ABS(ALPHA) .LE. 1.D-10) THEN
C FY0.D0
C TZ0.D0
C ELSE IF(ABS(ALPHA) .LE. ASTAR) THEN
C H1.D0 - CA*ABS(TAN(ALPHA))/(3.D0*U*ABS(FZ))
C FY-U*ABS(FZ)*(1.D0-H**3)*SIGN(1.0D0,ALPHA)
C TZU*ABS(FZ)*2.D0*R2*(1.D0-H)*(H**3)*SIGN
(1.0D0,ALPHA)
C ELSE
C FY-U*ABS(FZ)*SIGN(1.0D0,ALPHA)
C TZ0.D0
C ENDIF
C C
C C ********************************************
C -- Add camber force to FY - “Taut String” --
FYFYFZ*TAN(CAMBER)
C
Mitigate FY depending on “Friction Ellipse”
FR_ELLIP(FX/(FZ*U))**2(FY/(FZ*U*B))**2.0
IF (FR_ELLIP .GT. 1.0) THEN
LSLIPSLIP_C-5.0
IF(SLIP .LT. LSLIP) THEN
C -- Friction Ellipse treatment for comprehensive slip below
C critical slip ratio --
FY-((1-(FX/(FZ*U))**2)*(FZ*U*B)**2)**0.5*SIGN
(1.0D0,ALPHA)
ELSE
C -- Just kill the lateral force if slip ratio is above
C critical slip ratio --
USLIPSLIP_C15.0
SCMIN0.03
CALL STEP(SLIP, LSLIP, ONE, USLIP, SCMIN, IORD,
* SCFACT, ERFLG)
FY-((1-(FX/(FZ*U))**2)*(FZ*U*B)**2)**0.5*SIGN
(1.0D0,ALPHA)