Force: Gravity

Modifies a gravity force element.

<Force_Gravity

grav_x = "motionsolve_expression"

grav_y = "motionsolve_expression"

grav_z = "motionsolve_expression"

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.

<Force_Gravity

grav_x = "0."

grav_y = "0."

grav_z = "STEP(TIME,0,0,1,-9810)"

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_Vector_TwoBody.

Command Element
Description
Modifies an ACCGRAV element.
Declaration
def ACCGRAV(IGRAV=0.0, JGRAV=0.0, KGRAV=0.0):
Attributes
IGRAV	Modifies the acceleration due to gravity in the global X direction. The default value is 0.0.
JGRAV	Modifies the acceleration due to gravity in the global Y direction. The default value is 0.0.
KGRAV	Modifies the acceleration due to gravity in the global Z direction. The default value is 0.0.
Comments See Force_Gravity
Example
The example below shows the gravity component in mm/s2, modified to be in Y direction. ACCGRAV(IGRAV=0.0, JGRAV=-9810.0, KGRAV=0.0)