# Bushing Property File

The Altair Bushing Model reads a property file that contains all of the information required for a bushing at run-time. This property file is known as the Bushing Property file or General Bushing System property file and uses the extension .gbs.

The following table shows the structure of the .gbs file:
[HEADER]
[UNITS]
[GLOBAL]
[DIRECTIONS]
[FRICTION]
[SPLINE_STIFFNESS_FX]        [SPLINE_STIFFNESS_FY]        [SPLINE_STIFFNESS_FZ]
[CONSTANT_STIFFNESS_FX]      [CONSTANT_STIFFNESS_FY]      [CONSTANT_STIFFNESS_FZ]
[CUBIC_SIFFNESS_FX]          [CUBIC_STIFFNESS_FY]         [CUBIC_STIFFNESS_FZ]
[CONSTANT_DAMPING_FX]        [CONSTANT_DAMPING_FY]        [CONSTANT_DAMPING_FZ]
[RUBBER_DAMPING_FX]          [RUBBER_DAMPING_FY]          [RUBER_DAMPING_FZ]
[HYDROMOUNT_DAMPING_FX]      [HYDROMOUNT_DAMPING_FY]      [HYDROMOUNT_DAMPING_FZ]

[SPLINE_STIFFNESS_TX]        [SPLINE_STIFFNESS_TY]        [SPLINE_STIFFNESS_TZ]
[CONSTANT_STIFFNESS_TX]      [CONSTANT_STIFFNESS_TY]      [CONSTANT_STIFFNESS_TZ]
[CUBIC_STIFFNESS_TX]         [CUBIC_STIFFNESS_TY]         [CUBIC_STIFFNESS_TZ]
[CONSTANT_DAMPING_TX]        [CONSTANT_DAMPING_TY]        [CONSTANT_DAMPING_TZ]
[RUBBER_DAMPING_TX]          [RUBBER_DAMPING_TY]          [RUBBER_DAMPING_TZ]
[HYDROMOUNT_DAMPING_TX]      [HYDROMOUNT_DAMPING_TY]      [HYDROMOUNT_DAMPING_TZ]
The .gbs file uses the TeimOrbit format organized into the following blocks:
Block Type Description
HEADER Mandatory block specifying the file type, version, and format information for use by file readers.
UNITS Mandatory block that specifies the unit system for parameter values in the property file. This block enables file readers to convert the parameter values in the property file to those used in the simulation.
GLOBAL Mandatory block specifying whether or not to couple the X-, Y-, and Z-direction force computations and the X-, Y-, and Z-direction moment computations.
DIRECTIONS Mandatory block that specifies the force formulations active for each force and moment direction.
PARAMETER Parameter blocks for the active force methods for each direction. For each force direction of interest the .gbs file contains six blocks. These are shown in brown in the figure below. In order to conserve space, the force blocks are shown in multiple columns, though in the file they are organized one below the other. Since six possible directions of interest exist, the .gbs file can contain up to 36 blocks of information containing the force data.

The string, FX, FY, FZ, TX, TY, or TZ, is appended to the block name to identify the direction, for example: [CONSTANT_STIFFNESS_FZ]. Force models selected in the ACTIVITY table must have a corresponding parameter block in the .gbs file. Parameter blocks are available for the following force methods:

FRICTION Friction blocks support the parameters for the LuGre friction model—a model that supports both static and dynamic friction.

The following topics provides a detailed definition for each block: