# Select Force Models in the Bushing Property File

The .gbs file is an ASCII file that adheres to the TeimOrbit format. The .gbs file contains data in the form of blocks. Each block has a title that identifies what the block is, followed by the data.

The five types of generic blocks include:
• Units block
• Global block
• Directions block
• Friction block
The blocks are shown in blue in the figure below. In addition, for each force direction of interest, the .gbs file includes six blocks. These blocks are shown in gray. In order to conserve space, the force blocks are shown in multiple columns, though the actual blocks stack one below the other. Since six possible directions of interest exist, the .gbs file can include up to 36 blocks of force data.
[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 output force or torque in any given direction is the sum of forces or torques returned by the active force formulations for that direction. The (ACTIVITY) sub-block in the [DIRECTIONS] block in the property file defines the force models that are active. The directions block is a 6x6 matrix.
• Each column represents a force direction and each row represents one of the 6 force models.
• A one (1) in entry [I,J] indicates that for force model [I] is active for force direction [J].
• A zero (0) in entry [I,J] indicates that for force model [I] is inactive for force direction [J].
Note: You can select only one active stiffness model and one active damping model for any direction.
In the example shown below, stiffness models are shown in blue and damping models in red.
• For FX: SPLINE_STIFFNESS and RUBBER DAMPING are active
• For FY: CONSTANT_STIFFNESS and HYDROMOUNT DAMPING are active
• For TX: CUBIC_STIFFNESS and CONSTANT_DAMPING are active
• For TZ: CUBIC_STIFFNESS and RUBBER DAMPING are active
\$---------------------------------------------------------- DIRECTIONS
[DIRECTIONS]
(ACTIVITY)
{   formulation       FX  FY  FZ   TX  TY  TZ  }
'SPLINE_STIFFNESS'    1   0   0    0   0   0
'CONSTANT_STIFFNESS'  0   1   0    0   0   0
'CUBIC_STIFFNESS'     0   0   1    1   1   1
'CONSTANT_DAMPING'    0   0   1    1   1   0
'RUBBER_DAMPING'      1   0   0    0   0   1
'HYDROMOUNT_DAMPING'  0   1   0    0   0   0

Therefore the net force output for any direction is the sum of the forces due to the active force formulations in that direction.