Defining and Reading Tire Property Files
Learn more about creating tire property files:
About Tire Property Files
When you create your own user tire model, you must also define your own tire property file. At a minimum, this file instructs Adams Tire to call your tire model to compute tire forces and moments during a simulation and supplies to Adams Tire required information about the tire.
Adams Tire requires every tire property file to supply:
■Tire model to be used (for example, a reference that causes Adams Tire to call your TYRSUB).
■Units of the data contained in the file.
■Dimensions of the tire: unloaded radius, width, and aspect ratio.
■Tire vertical stiffness and damping.
Because Adams Tire reads the above information from every tire property file, you must provide it in the form shown in the next sections.
Besides the required data, your property file can contain any information in any form you want. If you choose to structure the data in TeimOrbit format, MSC supplies a set of utilities for reading the data from your file. These utilities include routines to obtain unit conversion factors so you can convert data to SI units. For more information, see
Utilities for Reading Property Files.
Example Tire Property File
$-----------------------------------------------------------MDI_HEADER
[MDI_HEADER]
FILE_TYPE
= 'tir'
FILE_VERSION
= 2.0
FILE_FORMAT
= 'ASCII'
(COMMENTS)
{comment_string}
'Tire
- XXXXXX'
'Pressure
- XXXXXX'
'Test Date
- XXXXXX'
'Test tire'
'New File Format v2.1'
$----------------------------------------------------------------units
[UNITS]
LENGTH
= 'mm'
FORCE
= 'newton'
ANGLE
= 'degree'
MASS
= 'kg'
TIME
= 'sec'
$----------------------------------------------------------------model
[MODEL]
! use mode
1
2
! ---------------------------------
! smoothing
X
!
PROPERTY_FILE_FORMAT
= 'USER'
FUNCTION_NAME
= 'TYR501'
USE_MODE
= 2.0
$------------------------------------------------------------dimension
[DIMENSION]
UNLOADED_RADIUS
= 309.9
WIDTH
= 235.0
ASPECT_RATIO
= 0.45
$-----------------------------------------------------------parameter
[PARAMETER]
VERTICAL_STIFFNESS
= 310.0
VERTICAL_DAMPING
= 3.1
ROLLING_RESISTANCE
= 0.0
CSLI
= 1000.0
CALPHA
= 800.0
CGAMMA
= 0.0
UMIN
= 0.9
UMAX
= 1.0
RELAXATION_LENGTH
= 0.0
$---------------------------------------------------------------shape
[SHAPE]
{radial width}
1.0
0.0
1.0
0.2
1.0
0.4
1.0
0.5
1.0
0.6
1.0
0.7
1.0
0.8
1.0
0.85
1.0
0.9
0.9
1.0
Required Blocks
Your tire property file must contain a specific set of blocks that Adams Tire expects. These blocks can appear in any order, and your tire property file can contain other blocks that you define. The blocks that your tire property file must contain are:
[MODEL] Block
The [MODEL] block specifies the tire model that Adams Tire will use. For your tire model, specify a property file format of “USER”and a function name that is the entry point to the tire functions, such as:
[MODEL]
PROPERTY_FILE_FORMAT = ‘USER’
FUNCTION_NAME = ‘TYR501’
In the example above, Adams Tire calls subroutine TYR501 to read the tire property file and to evaluate the tire forces and moments.
[UNITS] Block
A [UNITS] block specifies the units of the data in the tire property file. This enables Adams Tire to convert any data it reads from the tire property file to SI units (meters kilograms, Newtons, seconds, radian). Any data your TYRSUB reads from the tire property file should also be converted to SI units, as the example TYRSUB illustrates.
An example [UNITS] block is shown below:
UNITS]
LENGTH
= 'mm'
FORCE
= 'newton'
ANGLE
= 'radian'
MASS
= 'kg'
TIME
= 'sec'
The allowed values for unit strings are:
FORCE: | FORCE : 'KG_FORCE', 'NEWTON', 'KNEWTON','POUND_FORCE', 'KPOUND_FORCE', 'DYNE', 'OUNCE_FORCE' |
MASS: | 'KG', 'GRAM', 'POUND_MASS', 'KPOUND_MASS', 'SLUG', 'OUNCE_MASS' |
LENGTH: | 'KM', 'METER', ' CM', 'MM', 'MILE', 'FOOT', 'INCH' |
TIME: | 'MILLISECOND', 'SEC', 'MINUTE', 'HOUR' |
ANGLE: | 'DEGREE', 'RADIAN' |
Note: | You can use the utility subroutine ATRTOU to read the [UNITS] block from a tire property file and then use the utility subroutine ACUNFN to obtain unit conversion factors. For more information, see ATRTOU and ACUNFN. |
[DIMENSION] Block
The [DIMENSION] block specifies the tire's unloaded radius, width, and aspect ratio. Adams Tire uses these values to size wheel and tire graphics.
[DIMENSION]
UNLOADED_RADIUS = real_value > 0
WIDTH = real_value > 0
ASPECT_RATIO = 1 > real_value > 0
[PARAMETER] Block
The [PARAMETER] block specifies the vertical stiffness and damping of the tire. Adams Tire makes this information available to Adams Car during suspension analysis by incorporating a test-rig tire.
[PARAMETER]
VERTICAL_STIFFNESS = real_value > 0
VERTICAL_DAMPING = real_value >= 0