LoadForceVector

Load with (3D) force vector; attached to position-based marker.

Additional information for LoadForceVector:

  • Requested Marker type = Position
  • Short name for Python = Force
  • Short name for Python visualization object = VForce

The item LoadForceVector with type = ‘ForceVector’ has the following parameters:

  • name [type = String, default = ‘’]:
    load’s unique name
  • markerNumber [type = MarkerIndex, default = invalid (-1)]:
    marker’s number to which load is applied
  • loadVector [\({\mathbf{f}}\), type = Vector3D, default = [0.,0.,0.]]:
    vector-valued load [SI:N]; in case of a user function, this vector is ignored
  • bodyFixed [type = Bool, default = False]:
    if bodyFixed is true, the load is defined in body-fixed (local) coordinates, leading to a follower force; if false: global coordinates are used
  • loadVectorUserFunction [\(\mathrm{UF} \in \Rcal^3\), type = PyFunctionVector3DmbsScalarVector3D, default = 0]:
    A Python function which defines the time-dependent load and replaces loadVector; see description below; NOTE that in static computations, the loadFactor is always 1 for forces computed by user functions (this means for the static computation, that a user function returning [t*5,t*1,0] corresponds to loadVector=[5,1,0] without a user function); NOTE that forces are drawn using the value of loadVector; thus the current values according to the user function are NOT shown in the render window; however, a sensor (SensorLoad) returns the user function force which is applied to the object; to draw forces with current user function values, use a graphicsDataUserFunction of a ground object
  • visualization [type = VLoadForceVector]:
    parameters for visualization of item

The item VLoadForceVector has the following parameters:

  • show [type = Bool, default = True]:
    set true, if item is shown in visualization and false if it is not shown

DESCRIPTION of LoadForceVector

Details

The load vector acts on a body or node via the local (bodyFixed = True) or global coordinates of a body or at a node. The marker transforms the (translational) force via the according jacobian matrix of the object (or node) to object (or node) coordinates.

Userfunction: loadVectorUserFunction(mbs, t, loadVector)

A user function, which computes the force vector depending on time and object parameters, which is hereafter applied to object or node.

arguments / return
type or size
description
mbs
MainSystem
provides MainSystem mbs to which load belongs
t
Real
current time in mbs
loadVector
Vector3D
\({\mathbf{f}}\) copied from object; WARNING: this parameter does not work in combination with static computation, as it is changed by the solver over step time
returnValue
Vector3D
computed force vector

User function example:

from math import sin, cos, pi
def UFforce(mbs, t, loadVector):
    return [loadVector[0]*sin(t*10*2*pi),0,0]

Relevant Examples and TestModels with weblink:

The web version may not be complete. For details, consider also the Exudyn PDF documentation : theDoc.pdf