Force: Gravity

Command ElementModifies a gravity force element.

Format

<Force_Gravity
     grav_x    = "motionsolve_expression"     
     grav_y    = "motionsolve_expression"     
     grav_z    = "motionsolve_expression" 
/>

Attributes

grav_x
Defines the acceleration due to gravity in the global X direction. The default value is 0.0.
grav_y
Defines the acceleration due to gravity in the global Y direction. The default value is 0.0.
grav_z
Defines the acceleration due to gravity in the global X direction. The default value is 0.0.

Example

<Force_Gravity
     grav_x = "0."
     grav_y = "0."
     grav_z = "STEP(TIME,0,0,1,-9810)"
/>

Comments

  1. grav_x, grav_y, grav_z may be specified as real numbers or as function expressions. This allows you to model gravity as a function of time. If gravity is modeled as a function of displacements, forces or other states of the system, MotionSolve may have difficulty finding a converged solution.

    To represent state dependent gravity effects, use Force: Two Body Vector.