.. _examples-ancfslidingjoint:

*******************
ANCFslidingJoint.py
*******************

You can view and download this file on Github: `ANCFslidingJoint.py <https://github.com/jgerstmayr/EXUDYN/tree/master/main/pythonDev/Examples/ANCFslidingJoint.py>`_

.. code-block:: python
   :linenos:

   #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   # This is an EXUDYN example
   #
   # Details:  3D ANCF Cable element with sliding joint test
   #
   # Author:   Johannes Gerstmayr
   # Date:     2026-03-02
   #
   # Copyright:This file is part of Exudyn. Exudyn is free software. You can redistribute it and/or modify it under the terms of the Exudyn license. See 'LICENSE.txt' for more details.
   #
   #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   
   import exudyn as exu
   from exudyn.utilities import ObjectANCFCable, VObjectANCFCable, InertiaCuboid, MarkerBodyRigid,\
                           NodeGenericData, ObjectJointSliding, MarkerBodyBeamShape
   import exudyn.graphics as graphics #only import if it does not conflict
   from exudyn.beams import GenerateStraightLineANCFCable
   
   import numpy as np
   
   #create an environment for mini example
   SC = exu.SystemContainer()
   mbs = SC.AddSystem()
   
   L = 2
   hg = 1 #ground offset y
   rCable = 0.01
   oGround=mbs.CreateGround(referencePosition= [0,0,0],
                            graphicsDataList=[graphics.CheckerBoard([0.5*L,-hg,0], normal=[0,1,0],size=3),
                                              graphics.Cylinder([0,0,0],[0,-hg,0],radius=rCable*2, color=graphics.color.orange),
                                              graphics.Cylinder([L,0,0],[0,-hg,0],radius=rCable*2, color=graphics.color.orange)
                                              ])
   
   rhoA = 7800*rCable**2*np.pi
   EA = 0.25*100000.
   EI = 1
   
   nCables = 1
   for i in range(nCables):
       p0 = np.array([0,0,i*0.1])
       p1 = p0 + [L,0,0]
   
       cable = ObjectANCFCable(physicsMassPerLength=rhoA, 
                     physicsBendingStiffness = EI, 
                     physicsBendingDamping = EI*0.02,
                     physicsAxialStiffness=EA,
                     physicsAxialDamping=EA*0.02,
                     visualization=VObjectANCFCable(radius = rCable),
                     )
   
       ancf=GenerateStraightLineANCFCable(mbs=mbs,
                     positionOfNode0=p0, positionOfNode1=p1,
                     numberOfElements=48, #converged to 4 digits
                     cableTemplate=cable, #this defines the beam element properties
                     massProportionalLoad = [0,-9.81,0],
                     fixedConstraintsNode0 = [1,1,1, 0,1,1], #add constraints for pos and rot (r'_y,r'_z)
                     fixedConstraintsNode1 = [1,1,1, 0,1,1], #add constraints for pos and rot (r'_y,r'_z)
                     )
       #ancf=[cableNodeList, cableObjectList, loadList, cableNodePositionList, cableCoordinateConstraintList]
   
   lElem = mbs.GetObject(ancf[1][0])['physicsLength']
   
   slidingCoordinateInit = 0.1*L
   initialLocalMarker = int(slidingCoordinateInit/lElem) #second element
   
   hy = 0.4 #height of rigid body
   sz = 5*rCable #z-displacement of rigid body
   cubeLengths = [5*rCable,hy-2*rCable,10*rCable]
   oRigid = mbs.CreateRigidBody(referencePosition=[slidingCoordinateInit, -0.5*hy,-sz],
                       inertia=InertiaCuboid(2*7800, cubeLengths),
                       gravity=[0,-9.81,0],
                       graphicsDataList=[graphics.Brick(size=cubeLengths, color=graphics.color.dodgerblue),
                                         graphics.Sphere([0,0.5*hy,sz], radius=2*rCable, color=graphics.color.red)]
                       )
   mRigidTop = mbs.AddMarker(MarkerBodyRigid(bodyNumber=oRigid, localPosition=[0,0.5*hy,sz]))
   
   addSlidingJoint = True
   if addSlidingJoint:
   
   
       cableMarkerList = []#list of MarkerBodyBeamShape
       offsetList = []     #list of offsets counted from first cable element; needed in sliding joint
       offset = 0          #first cable element has offset 0
       for item in ancf[1]: #create markers for cable elements
           m = mbs.AddMarker(MarkerBodyBeamShape(bodyNumber = item))
           cableMarkerList += [m]
           offsetList += [offset]
           offset += lElem
   
       nodeDataSJ = mbs.AddNode(NodeGenericData(initialCoordinates=[initialLocalMarker,slidingCoordinateInit],numberOfDataCoordinates=2)) #initial index in cable list
       slidingJoint = mbs.AddObject(ObjectJointSliding(markerNumbers=[mRigidTop,cableMarkerList[initialLocalMarker]], 
                                                       constrainRotations=[0,0,0],
                                                       slidingMarkerNumbers=cableMarkerList, slidingMarkerOffsets=offsetList, 
                                                       nodeNumber=nodeDataSJ))
   
   
   #assemble and solve system for default parameters
   mbs.Assemble()
   
   endTime=10
   stepSize = 0.5e-3
   
   simulationSettings = exu.SimulationSettings()
   
   #simulationSettings.solutionSettings.writeSolutionToFile = False
   simulationSettings.solutionSettings.solutionWritePeriod = 0.02 #data not used
   simulationSettings.solutionSettings.binarySolutionFile = True
   simulationSettings.solutionSettings.outputPrecision = 6 #float
   simulationSettings.solutionSettings.sensorsWritePeriod = 0.002 #data not used
   simulationSettings.timeIntegration.verboseMode = 1 #turn off, because of lots of output
   simulationSettings.linearSolverType = exu.LinearSolverType.EigenSparse
   simulationSettings.parallel.numberOfThreads = 1
   simulationSettings.displayComputationTime = True
   simulationSettings.displayStatistics = True
   
   simulationSettings.timeIntegration.numberOfSteps = int(endTime/stepSize)
   simulationSettings.timeIntegration.endTime = endTime
   simulationSettings.timeIntegration.newton.useModifiedNewton = True
   
   #simulationSettings.timeIntegration.simulateInRealtime = True
   #simulationSettings.timeIntegration.realtimeFactor = 0.5
   
   SC.visualizationSettings.openGL.multiSampling = 4
   
   SC.visualizationSettings.general.graphicsUpdateInterval = 0.02
   SC.visualizationSettings.view0.window.renderWindowSize=[1200,1024]
   SC.visualizationSettings.view0.camera.perspective = 0.5
   SC.visualizationSettings.openGL.light0.shadow = 0.3
   SC.visualizationSettings.openGL.light0.position = [2,10,2,1]
   SC.visualizationSettings.nodes.show = False
   SC.visualizationSettings.loads.show = False
   SC.visualizationSettings.connectors.show = False
   #+++++++++++++++++++++++++++++++++++++++++++++++++++++++
   
   SC.renderer.Start()
   SC.renderer.SetModelView(zoom=1.335652,rotationVector=[0.7933899,0.5903195,0.2917689],centerPoint=[1.012,-0.349,0])
   SC.renderer.DoIdleTasks()
   
   mbs.SolveDynamic(simulationSettings)
   
   SC.renderer.DoIdleTasks()
   SC.renderer.Stop() #safely close rendering window!
   
   mbs.SolutionViewer()