HTire Parameters Common to all MF Variants

The following is a list of parameters which are common to all Magic Formula variants.

Section [COSIN_HEADER]

The [COSIN HEADER] section is the place to specify a comment and a file version number. If the section is not found, all tire models of the FTire Tire Model Family assume the file is specified in the newest ASCII format version.
Note: The [COSIN HEADER] section is optional.

Section [UNIT]

The physical units of parameters in subsequent sections are defined in the table below:
Name in input file Unit Required Default value Explanation
force - No N Force unit, defined by case-insensitive character string. Supported units are:
  • kiloNewton, kNewton, kN
  • dekaNewton, daN
  • Newton, N, kilogram_force, kg_force
  • pound_force, poundforce, poundf, lbf
  • kpound_force, kpoundforce
  • dyne, dyn
  • ounce_force, ounceforce
mass - No kg Mass unit, defined by case-insensitive character string. Supported units are:
  • kilogram, kg
  • gram, g
  • pound, lbm, lb, pound_mass, poundmass, poundm
  • kpound_mass, kpoundmass
  • slug
  • ounce_mass, ouncemass
length - No m Length unit, defined by case-insensitive character string. Supported units are:
  • kilometer, km
  • meter, meters, m
  • centimeter, cm
  • millimeter, mm
  • inch, in
  • foot, ft
  • mile
time - No s Time unit, defined by case-insensitive character string. Supported units are:
  • second, sec, s
  • millisecond, msec, ms
  • minute, min
  • hour, h
angle - No rad Angle unit, defined by case-insensitive character string. Supported units are:
  • degree, degrees, deg
  • grad
  • radian, rad, radians
If, in subsequent data item specifications, a unit is printed in italic letters (i.e. force, mass, length, time, or angle), the respective unit is chosen according to the settings in the [UNIT] section. Otherwise, the unit as given in the data item specification is used independent of the settings in the [UNIT] section.
Note: The [UNIT] section is optional.

Section [MODEL]

This section is the place to select the tire model and other related settings:
Name in input file Unit Required Default value Explanation
property_file_format - Yes - Tire model selection. The string is case-insensitive. Supported models are:
  • pac2002
  • pac89
  • htire (the MF variant is detected automatically)
  • rtire
  • ftire
  • fetire
Note: The models may be locked due to license restrictions.
tyreside - No asis If necessary, mirrors or zeros side-dependent data. Possible values are:
  • asis (data are not modified)
  • left (data are mirrored, if actual tire is on right vehicle side)
  • right (data are mirrored, if actual tire is on right vehicle side)
  • symmetric (data that cause an unbalance between the left and right side are modified during initialization, resulting in a symmetric behavior)
Note: By default, no data are modified (asis).
use_mode - No -1 Activation of model features are:
  • -1: activates all model features; same as use mode 24
  • 0: only uses vertical force
  • 1..4: uses model in steady-state mode
  • 11..14: uses model in transient mode
  • 21..24: uses model in enhanced steady-state mode (at present, no difference to use modes 11..14)
The right-most digit selects the forces to be computed:
  • 1: only longitudinal force and rolling resistance
  • 2: only lateral force and aligning torque
  • 3: all forces/torques, but disregards combined slip conditions
  • 4: all forces/torques, taking into account combined slip conditions
Note: By default, the most complex use mode (24) is used.
separate_animation - No 0

Requests and specifies properties of an extra animation window for all tire model instances which are called by CTI. The value of separate_animation consists of up to 8 decimal digits. The definition of each mode is defined below.

Select animation mode:
  • 0 no animation
  • 1 normal mode
  • 2 movie preparation
  • 3 full screen
  • 4 small window
  • 5 translucent structure
  • 7 multiple exposure
Note: Not all animation modes are available for all tire model types.
Select contour plot type (only FTire):
  • 0 no contour plot
  • 1 contour plot: contact pressure distribution
  • 2 contour plot: longitudinal shear stress
  • 3 contour plot: lateral shear stress
  • 4 contour plot: friction coefficient
  • 5 contour plot: sliding velocity
  • 6 contour plot: tread temperature
  • 7 contour plot: tread depth
  • 8 contour plot: power loss density
Select running diagram type:
  • 0 no running diagrams
  • 1 running diagrams: forces
  • 2 running diagrams: torques
  • 3 running diagrams: handling signals
Show interactive sliders, if available:
  • 0 no sliders
  • 1 show sliders
Select camera setting:
  • 0 camera focussing rim center
  • 1 camera focussing contact patch
  • 2 bird's view
  • 3 rim-fixed camera
Select tire structure visualization (only FTire):
  • 0 tire structure rendered
  • 1 tire structure wire-framed
Select road visualization:
  • 0 no road
  • 1 auto road display, defined by road type
  • 2 single line road
  • 3 grid road
  • 4 rendered road
Select sound (if available):
  • 0 no sound
  • 1 sound
cosingl_path - No working directory and more

Path to the COSIN/gl animation program cosingl (optional). By default, CTI searchs for this program in a certain predefined list of directories. This list includes the working directory, the home directory, the root directory, and the directory specified by the environmental variable COSINGLPATH.

If COSIN/gl cannot be found, CTI runs anyway, but does not display the on-line animation. This does not affect any simulation results.
road_grid_size length No 600x300 mm Approximate width and length (same value for both) of road visualization grid in animation window.
road_grid_line_dis length No 5x50 mm Approximate grid line distance (same value for x and y direction) of road visualization in animation window.
animation_time_step time No same as simulation time step Approximate time step for on-line animation, to be specified in the time unit of the data file. If zero or not specified, an approximate animation time step of 1 ms is used.
animation_start time No 0.0 Approximate simulation time to begin animation. If not specified, animation (if requested) begins with simulation.
animation_end time No unlimited Approximate simulation time to end animation. If not specified, animation ends with simulation.
force_scaling - No 1.0 Factor that scales all kinds of force display in the animation window (sliders, forces in running diagrams, contact force vectors, etc.). Default value is 1.0.

Section [DIMENSION]

This section collects all data necessary to specify the tire size:
Name in input file Unit Required Default value Explanation
unloaded_radius length Yes, in case of 2002 variant estimated Maximum radius of unloaded tire. By default, estimated on basis of tire dimension.
width length Yes - Maximum width of unloaded tire.
aspect_ratio - Yes - Tire aspect ratio.
Note: This value is not specified in %, but in a value between 0 and 1.
rim_radius length Yes - Rim (bead seat) radius.
rim_width length Yes, in case of 2002 variant estimated Rim (bead seat) width. By default, estimated on basis of tire dimension.
rolling_circumference length No estimated Rolling circumference. By default, estimated on basis of tire dimension.

Section [PARAMETER] or [VERTICAL]

This section collects data necessary to specify the tire radial stiffness and damping properties, and other stiffness-related data:
Name in input file Unit Required Default value Explanation
vertical_stiffness force

/length

 (Yes) - Mean radial stiffness (required if no section [DEFLECTION_LOAD_CURVE] is specified).
vertical_damping force

/time

/length

 No 0 Mean radial damping coefficient.
step_size_contact_plane_calc length No 50 mm Numerical step-size to approximate the road normal vector by numerical differentiation. Should be roughly half the contact patch width.
Fnomin N Yes, in case of 2002 variant LI load Nominal wheel load.
breff - Yes, in case of 2002 variant 9 Parameter Breff in determination of effective rolling radius (eq. (A3.7), p. 617 in [PAC]).
dreff - Yes, in case of 2002 variant 0.23 Parameter Dreff in determination of effective rolling radius (eq. (A3.7), p. 617 in [PAC]).
freff - Yes, in case of 2002 variant 0.01 Parameter Freff in determination of effective rolling radius (eq. (A3.7), p. 617 in [PAC]).
lateral_stiffness force

/length

 No infinity Lateral stiffness of the non-rolling tire; used for contact patch shift estimation due to tire forces.
longitudinal_stiffness force

/length

 No infinity Longitudinal stiffness of the non-rolling tire; used for contact patch shift estimation due to tire forces and for the influence of wheel load on overturning torque.
rolling_resistance - No 0.012 Dimensionless rolling resistance coefficient.
relaxation_length_Fx length No 0 Relaxation length of longitudinal force.
max_time_constant_Fx time No 0.3 s Time constant upper bound for longitudinal force lag.
relaxation_length_reduction_Fx - No 0.7 Relaxation length reduction of longitudinal force decrease relative to force increase.
relaxation_length_Fy length No 0 Relaxation length of side force.
max_time_constant_Fy time No 0.3s Time constant upper bound for side force lag.
relaxation_length_reduction_Fy - No 0.7 Relaxation length reduction of side force decrease relative to force increase.
relaxation_length_Mz length No 0 Relaxation length of aligning torque.
max_time_constant_Mz time No 0.3 s Time constant upper bound for aligning torque lag.
relaxation_length_reduction_Mz - No 0.7 Relaxation length reduction of aligning torque decrease relative to torque increase.
model_switch_ref_speed length

/time

 No 0.2 Forward speed at which model is smoothly switched from ‘slip-based’ to ‘displacement-based’. The latter mode is a simplified approach for the standing tire. The reference speed is used if the calling integrator time-step is 1ms; shorter or longer time-steps decrease or increase the switching velocity, respectively.

Section [DEFLECTION_LOAD_CURVE]

This section provides an alternative to vertical_stiffness. If specified, the x and y data in this section define a smooth spline, representing the non-linear deflection/load characteristic of the tire. Arbitrarily, many x and y data of tire deflection (length) and radial load (force) can be specified, one or more in a line. Deflection values must be monotonously increasing. TeimOrbit compatible comment lines are allowed between the data lines.

Below is an example of a valid [DEFLECTION_LOAD_CURVE] section:
[DEFLECTION_LOAD_CURVE]
0     0.0
5   400.0
10 1250.0
20 4000.0
30 8500.0
Note: The [DEFLECTION_LOAD_CURVE] section is optional.