GFORCE
The GFORCE command redefines and/or list the data for a GFORCE statement that defines a force element that consists of three orthogonal translational force components and three orthogonal torque components.
Format
Arguments
FUNCTION=USER(r1[,...,r30]) | Respecifies up to thirty user-defined constants to compute the force components in a user-defined subroutine GFOSUB. |
FX=e | Respecifies the magnitude and sign of the x component of the GFORCE translational force. Adams Solver (C++) applies this force parallel to the x-axis of the RM marker. |
FY=e | Respecifies the magnitude and sign of the y component of the GFORCE translational force. Adams Solver (C++) applies this force parallel to the y-axis of the RM marker. |
FZ=e | Respecifies the magnitude and sign of the z component of the GFORCE translational force. Adams Solver (C++) applies this force parallel to the z-axis of the RM marker. |
FXYZ=e3d | Respecifies the 3D vector expression for the force component of the GFORCE relative to the RM marker. |
TXYZ=e3d | Respecifies the 3D vector expression for the torque component of the GFORCE relative to the RM marker. |
I=id | Respecifies the marker at which Adams Solver (C++) applies the forces and torques. You must ensure that the I marker is a fixed marker and on a different part than the JFLOAT marker. Because I is a fixed marker, Adams Solver (C++) always applies the force at a fixed point on the part containing the I marker. |
JFLOAT=id | Respecifies the marker at which Adams Solver (C++) applies the reaction forces and torques. You must ensure that the JFLOAT marker is a floating marker and on a different part than the I marker. Adams Solver (C++) moves the JFLOAT marker to keep it superimposed on the I marker, meaning the point of application of the reaction force may move with respect to its part. Adams Solver (C++) does not calculate reaction forces when the JFLOAT marker is on the ground part. |
LIST | Lists the current values of the GFORCE arguments. |
RM=id | Respecifies the marker and therefore the coordinate system in which the force and torque components are specified. You must ensure that RM is a fixed marker. RM may be the same as I and may be fixed on any part in your system. |
ROUTINE=libname::subname | Specifies an alternative library and name for the user subroutine GFOSUB. Learn more about the ROUTINE Argument. |
TX=e | Respecifies the magnitude and sign of the x component of the GFORCE rotational torque. Adams Solver (C++) applies this torque parallel to the x-axis of the RM marker in the sense of the right-hand rule (that is, a positive torque causes a counterclockwise rotation). |
TY=e | Respecifies the magnitude and sign of the y component of the GFORCE rotational torque. Adams Solver (C++) applies this torque parallel to the y-axis of the RM marker in the sense of the right-hand rule (that is, a positive torque causes a counterclockwise rotation). |
TZ=e | Respecifies the magnitude and sign of the z component of the GFORCE rotational torque. Adams Solver (C++) applies this torque parallel to the z-axis of the RM marker in the sense of the right-hand rule (that is, a positive torque causes a counterclockwise rotation). |
Extended Definition
The GFORCE command lists or redefines a force element that consists of three mutually orthogonal translational force components and three orthogonal torque components. You can alter one or both points of force and torque application, change the force reference marker, and change the force and torque function expressions or the parameters passed to the GFOSUB user-written subroutine.
After a change to a GFORCE, Adams Solver (C++) reprocesses the model at the next SIMULATE command, as if it had just been read in from the dataset. During the reprocessing, Adams Solver (C++) checks the entire model for consistency, reinitializes user subroutines, and recomputes initial conditions.
While checking, Adams Solver (C++) verifies that the model is still valid with the new GFORCE. If, for example, the GFORCE function expression refers to an inactive element, Adams Solver (C++) issues an error.
Adams Solver (C++) also reinitializes all user subroutines to re-establish functional dependencies. For each element that refers to a user-written subroutine, Adams Solver (C++) calls the user-written subroutine with IFLAG set to true.
Prior to the actual simulation, Adams Solver (C++) computes initial conditions for the model. If this is the first simulation, Adams Solver begins with the positions and velocities specified in the dataset. If you ran a previous simulation, Adams Solver begins with the final displacements and velocities. Adams Solver (C++) then adjusts the initial conditions to ensure that they are consistent with the model constraints. If this is the first simulation, Adams Solver (C++) also maintains any user supplied joint initial-conditions and positions specified as EXACT.
Tip: | Depending on the nature of the desired force relationship, the RM marker may belong to the same part as the I marker or the JFLOAT marker, or to a third, unrelated part. |
Caution: | The user-defined functions FX, FY, FZ, TX, TY, TZ, FXYZ and TXYZ should be smooth, continuous, and single-valued. These conditions make the solution process very effective. |
Example 1
GFORCE/1, I=8, JFLOAT=6, RM=7, LIST, &
FY = 0/ &
FZ = 0/ &
TY = 0/ &
TZ = 0
FY = 0/ &
FZ = 0/ &
TY = 0/ &
TZ = 0
This GFORCE command redefines and lists the general, six-component force acting between fixed Marker 310 and floating Marker 9910. The force and torque components FY, FZ, TY, and TZ are set to zero along the y and z axes of the reference marker, which is Marker 310. Adams Solver (C++) superimposes floating Marker 9910 on Marker 310 and applies the FX and TX reaction force and torque at that point.
Example 2
GFORCE/1, I=8, JFLOAT=6, RM=7, LIST, &
FXYZ = -20*DXYZ(8, 22, 22) - [0,0, SIN(TIME)]
This GFORCE command redefines the force component using vector 3D expressions.
See other Forces available.