LoadCoordinate

Load with scalar value, which is attached to a coordinate-based marker; the load can be used e.g. to apply a force to a single axis of a body, a nodal coordinate of a finite element or a torque to the rotatory DOF of a rigid body.

Additional information for LoadCoordinate:

  • Requested Marker type = Coordinate

The item LoadCoordinate with type = ‘Coordinate’ 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
  • load [\(f\), type = Real, default = 0.]:
    scalar load [SI:N]; in case of a user function, this value is ignored
  • loadUserFunction [\(\mathrm{UF} \in \Rcal\), type = PyFunctionMbsScalar2, default = 0]:
    A Python function which defines the time-dependent load and replaces the load; see description below; see also notes on loadFactor and drawing in LoadForceVector!
  • visualization [type = VLoadCoordinate]:
    parameters for visualization of item

The item VLoadCoordinate 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 LoadCoordinate

Details

The scalar load is applied on a coordinate defined by a Marker of type ‘Coordinate’, e.g., MarkerNodeCoordinate. This can be used to create simple 1D problems, or to simply apply a translational force on a Node or even a torque on a rotation coordinate (but take care for its meaning).

Userfunction: loadUserFunction(mbs, t, load)

A user function, which computes the scalar load depending on time and the object’s load parameter.

arguments / return
type or size
description
mbs
MainSystem
provides MainSystem mbs to which load belongs
t
Real
current time in mbs
load
Real
\({\mathbf{b}}\) 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
Real
computed load

User function example:

from math import sin, cos, pi
#this example uses the object's stored parameter load to compute a time-dependent load
def UFload(mbs, t, load):
    return load*sin(10*(2*pi)*t)

n0=mbs.AddNode(Point())
nodeMarker = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=n0,coordinate=0))
mbs.AddLoad(LoadCoordinate(markerNumber = markerCoordinate,
                           load = 10,
                           loadUserFunction = UFload))

Relevant Examples and TestModels with weblink:

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