ObjectANCFBeam

A 3D beam finite element based on the absolute nodal coordinate formulation, using two nodes. The localPosition \(x\) of the beam ranges from \(-L/2\) (at node 0) to \(L/2\) (at node 1). The axial coordinate is \(x\) (first coordinate) and the cross section is spanned by local \(y\)/\(z\) axes; assuming dimensions \(w_y\) and \(w_z\) in cross section, the local position range is \(\in [[-L/2,L/2],\, [-wy/2,wy/2],\, [-wz/2,wz/2] ]\). NOTE: Requires further development and tests!

Additional information for ObjectANCFBeam:

  • This Object has/provides the following types = Body, MultiNoded
  • Requested Node type = Position + Orientation
  • Short name for Python = ANCFBeam
  • Short name for Python visualization object = VANCFBeam

The item ObjectANCFBeam with type = ‘ANCFBeam’ has the following parameters:

  • name [type = String, default = ‘’]:
    objects’s unique name
  • nodeNumbers [type = NodeIndex2, default = [invalid [-1], invalid [-1]]]:
    two node numbers for beam element
  • physicsLength [\(L\), type = PReal, default = 0.]:
    [SI:m] reference length of beam; such that the total volume (e.g. for volume load) gives \(\rho A L\); must be positive
  • sectionData [type = BeamSection, default = BeamSection()]:
    data as given by exudyn.BeamSection(), defining inertial, stiffness and damping parameters of beam section.
  • crossSectionPenaltyFactor [\(k_{cs} = [f_{yy},\,f_{zz},\,f_{yz}]\tp\), type = Vector3D, default = [1.,1.,1.]]:
    [SI:1] additional penalty factors for cross section deformation, which are in total \(k_{cs} = [f_{yy}\cdot EA,\, f_{zz}\cdot EA,\, f_{yz}\cdot (GA_y+GA_z)]\tp\)
  • crossSectionDamping [\(d_{cs} = [d_{fyy},\,d_{fzz},\,d_{fyz}]\tp\), type = Vector3D, default = [0.,0.,0.]]:
    [SI:1] viscous damping according to penalty factors for cross section deformation; the damping is relative to the stiffness and should be thus usually much smaller than 1; the viscous damping factors read \(d_{cs} = [d_{fyy}\cdot EA,\, d_{fzz}\cdot EA,\, d_{fyz}\cdot (GA_y+GA_z)]\tp\)
  • visualization [type = VObjectANCFBeam]:
    parameters for visualization of item

The item VObjectANCFBeam has the following parameters:

  • show [type = Bool, default = True]:
    set true, if item is shown in visualization and false if it is not shown; geometry is defined by sectionGeometry
  • sectionGeometry [type = BeamSectionGeometry, default = BeamSectionGeometry()]:
    defines cross section shape used for visualization and contact
  • color [type = Float4, default = [-1.,-1.,-1.,-1.]]:
    RGBA color of the object; if R==-1, use default color

DESCRIPTION of ObjectANCFBeam

The following output variables are available as OutputVariableType in sensors, Get…Output() and other functions:

  • Position:
    global position vector of local position vector
  • Displacement:
    global displacement vector of local position vector
  • Velocity:
    global velocity vector of local position vector
  • VelocityLocal:
    global velocity vector of local position vector
  • AngularVelocity:
    global angular velocity vector of local (axis) position vector
  • AngularVelocityLocal:
    local angular velocity vector of local (axis) position vector
  • Acceleration:
    global acceleration vector of local position vector
  • Rotation:
    3D Tait-Bryan rotation components of cross section rotation
  • RotationMatrix:
    rotation matrix of cross section rotation as 9D vector

Detailed description coming later.

Relevant Examples and TestModels with weblink:

ANCFBeamEigTest.py (TestModels/), ANCFBeamTest.py (TestModels/), ANCFCableBeamDampingTest.py (TestModels/), geometricallyExactBeamTest.py (TestModels/), rightAngleFrame.py (TestModels/)

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