Directions Block

The Directions block selects what force formulations the simulation model uses for each force and torque direction. This is a mandatory block. The block contains a table where each row is a force method and each column a force or torque direction. To select or turn on a force formulation for a given force direction, enter 1 in the corresponding row and column. To turn off a force method for a given force direction, enter 0 (zero).
Parameter Type Units Description
ACTIVITY Sub-block - This sub-block is specified as (ACTIVITY)
FORMULATION String - Valid choices are:
  • 'SPLINE_STIFFNESS'
  • 'CUBIC_STIFFNESS'
  • 'CONSTANT_STIFFNESS'
FX Integer - Valid choices are:
  • 0 - do not select
  • 1 - select
FY Integer -
FZ Integer -
TX Integer -
TY Integer -
TZ Integer -
Some of the formulations are mutually exclusive and some of the formulations can be added in parallel.
  • Each force direction (one column in the matrix below) can contain only one stiffness model and one damping model.
  • HYDROMOUNT_DAMPING can be used for one translational direction only. Because the software does not impose this limitation, understanding the impracticality of fitting more than one hydromount per attachment is important.
  • Where HYDROMOUNT_DAMPING is used (for FX, FY, FZ), the RUBBER_DAMPING for the same direction cannot be used.
  • CONSTANT_STIFFNESS, SPLINE_STIFFNESS and CUBIC_STIFFNESS are mutually exclusive.
In the following example, the stiffness models are shown in blue and damping models in green.
  • For FX: SPLINE_STIFFNESS and RUBBER_DAMPING are active.
  • For FY: CONSTANT_STIFFNESS and HYDROMOUNT_DAMPING are active.
  • For FZ: CONSTANT_STIFFNESS and CONSTANT_DAMPING are active.
  • For TX: CUBIC_STIFFNESS and CONSTANT_DAMPING are active.
  • For TY: CONSTANT_STIFFNESS and CONSTANT_DAMPING are active.
  • For TZ: SPLINE_STIFFNESS and RUBBER_DAMPING are active.
$$---------------------------------------------------------- DIRECTIONS
[DIRECTIONS]
(ACTIVITY)
{   formulation       FX  FY  FZ   TX  TY  TZ  }
'SPLINE_STIFFNESS'    1   0   0    0   0   1
'CONSTANT_STIFFNESS'  0   1   1    0   1   0
'CUBIC_STIFFNESS'     0   0   0    1   0   0
'CONSTANT_DAMPING'    0   0   1    1   1   0
'RUBBER_DAMPING'      1   0   0    0   0   1
'HYDROMOUNT_DAMPING'  0   1   0    0   0   0

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