.. _testmodels-ancfcontactcircletest: ************************ ANCFcontactCircleTest.py ************************ You can view and download this file on Github: `ANCFcontactCircleTest.py `_ .. code-block:: python :linenos: #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ # This is an EXUDYN example # # Details: ANCF cable element contact with circle; test model fo ObjectContactCircleCable2D # # Author: Johannes Gerstmayr # Date: 2019-09-01 # # 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.itemInterface import * useGraphics = True #without test #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #you can erase the following lines and all exudynTestGlobals related operations if this is not intended to be used as TestModel: try: #only if called from test suite from modelUnitTests import exudynTestGlobals #for globally storing test results useGraphics = exudynTestGlobals.useGraphics except: class ExudynTestGlobals: pass exudynTestGlobals = ExudynTestGlobals() #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ SC = exu.SystemContainer() mbs = SC.AddSystem() #background rect = [-2,-2,4,2] #xmin,ymin,xmax,ymax background0 = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[rect[0],rect[1],0, rect[2],rect[1],0, rect[2],rect[3],0, rect[0],rect[3],0, rect[0],rect[1],0]} #background background1 = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[0,-1,0, 2,-1,0]} #background oGround=mbs.AddObject(ObjectGround(referencePosition= [0,0,0], visualization=VObjectGround(graphicsData= [background0, background1]))) #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #cable: mypi = 3.141592653589793 L=2 # length of ANCF element in m #L=mypi # length of ANCF element in m E=2.07e11 # Young's modulus of ANCF element in N/m^2 rho=7800 # density of ANCF element in kg/m^3 b=0.001 # width of rectangular ANCF element in m h=0.001 # height of rectangular ANCF element in m A=b*h # cross sectional area of ANCF element in m^2 I=b*h**3/12 # second moment of area of ANCF element in m^4 f=3*E*I/L**2 # tip load applied to ANCF element in N exu.Print("load f="+str(f)) exu.Print("EI="+str(E*I)) nGround = mbs.AddNode(NodePointGround(referenceCoordinates=[0,0,0])) #ground node for coordinate constraint mGround = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nGround, coordinate=0)) #Ground node ==> no action cableList=[] #for cable elements nodeList=[] #for nodes of cable markerList=[] #for nodes nc0 = mbs.AddNode(Point2DS1(referenceCoordinates=[0,0,1,0])) nodeList+=[nc0] nElements = 8 #8 original in test lElem = L / nElements for i in range(nElements): nLast = mbs.AddNode(Point2DS1(referenceCoordinates=[lElem*(i+1),0,1,0])) nodeList+=[nLast] elem=mbs.AddObject(Cable2D(physicsLength=lElem, physicsMassPerLength=rho*A, physicsBendingStiffness=E*I, physicsAxialStiffness=E*A, nodeNumbers=[int(nc0)+i,int(nc0)+i+1])) cableList+=[elem] mANCF0 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nc0, coordinate=0)) mANCF1 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nc0, coordinate=1)) mANCF2 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nc0, coordinate=3)) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF0])) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF1])) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF2])) #add gravity: markerList=[] for i in range(len(nodeList)): m = mbs.AddMarker(MarkerNodePosition(nodeNumber=nodeList[i])) markerList+=[m] fact = 1 #add (half) weight of two elements to node if (i==0) | (i==len(nodeList)-1): fact = 0.5 # first and last node only weighted half mbs.AddLoad(Force(markerNumber = m, loadVector = [0, -40*2*rho*A*fact*lElem, 0])) #will be changed in load steps #mANCFend = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nodeList[-1], coordinate=1)) #last marker #mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCFend])) #mGroundTip = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[L,0,0])) #mbs.AddObject(CartesianSpringDamper(markerNumbers=[mGroundTip,markerList[-1]], stiffness=[10,10,10], damping=[0.1,0.1,0.1])) #mGroundTip2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[L,0.2,0])) #mbs.AddObject(SpringDamper(markerNumbers=[mGroundTip2,markerList[-1]], stiffness=0.1, referenceLength=0.2)) #mANCFLast = mbs.AddMarker(MarkerNodePosition(nodeNumber=nLast)) #force #mbs.AddLoad(Force(markerNumber = mANCFLast, loadVector = [0, -1e8, 0])) #will be changed in load steps #mANCFrigid = mbs.AddMarker(MarkerBodyRigid(bodyNumber=elem, localPosition=[lElem,0,0])) #local position L = beam tip #mbs.AddLoad(Torque(markerNumber = mANCFrigid, loadVector = [0, 0, E*I*1*mypi])) #mANCFnode = mbs.AddMarker(MarkerNodeRigid(nodeNumber=nLast)) #local position L = beam tip #mbs.AddLoad(Torque(markerNumber = mANCFnode, loadVector = [0, 0, 3*E*I*1*mypi])) cStiffness = 1e3 cDamping = 0.02*cStiffness useContact = False if useContact: tipContact = False if tipContact: nodeData = mbs.AddNode(NodeGenericData(initialCoordinates=[0],numberOfDataCoordinates=1)) mbs.AddObject(ObjectContactCoordinate(markerNumbers=[mGround, mANCFend],nodeNumber = nodeData, contactStiffness = cStiffness, contactDamping=0*cDamping, offset = -0.8)) else: for i in range(len(nodeList)): mNC = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nodeList[i], coordinate=1)) nodeData = mbs.AddNode(NodeGenericData(initialCoordinates=[1],numberOfDataCoordinates=1)) #start with gap! mbs.AddObject(ObjectContactCoordinate(markerNumbers=[mGround, mNC], nodeNumber = nodeData, contactStiffness = cStiffness, contactDamping=0*cDamping, offset = -1)) nSegments = 4 #number of contact segments; must be consistent between nodedata and contact element initialGapList = [0.1]*nSegments #initial gap of 0.1 mGroundCircle = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[0.75*L,-0.5,0])) mGroundCircle2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[0.25*L,-0.15,0])) #mCable = mbs.AddMarker(MarkerBodyCable2DShape(bodyNumber=elem, numberOfSegments = nSegments)) #nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments)) #mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle, mCable], nodeNumber = nodeDataContactCable, # numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=cDamping, # circleRadius = 0.4, offset = 0)) for i in range(len(cableList)): mCable = mbs.AddMarker(MarkerBodyCable2DShape(bodyNumber=cableList[i], numberOfSegments = nSegments)) nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments)) mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle, mCable], nodeNumber = nodeDataContactCable, numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=0*cDamping, circleRadius = 0.2, offset = 0)) nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments)) mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle2, mCable], nodeNumber = nodeDataContactCable, numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=0*cDamping, circleRadius = 0.1, offset = 0)) #mbs.systemData.Info() mbs.Assemble() #exu.Print(mbs) simulationSettings = exu.SimulationSettings() #takes currently set values or default values simulationSettings.solutionSettings.writeSolutionToFile = True #simulationSettings.solutionSettings.outputPrecision = 4 simulationSettings.displayComputationTime = False simulationSettings.displayStatistics = False #SC.visualizationSettings.nodes.showNumbers = True SC.visualizationSettings.bodies.showNumbers = False #SC.visualizationSettings.connectors.showNumbers = True SC.visualizationSettings.nodes.defaultSize = 0.01 SC.visualizationSettings.markers.defaultSize = 0.01 SC.visualizationSettings.connectors.defaultSize = 0.01 SC.visualizationSettings.contact.contactPointsDefaultSize = 0.005 SC.visualizationSettings.connectors.showContact = 1 simulationSettings.solutionSettings.solutionInformation = "ANCF cable with imposed curvature or applied tip force/torque" simulationSettings.staticSolver.newton.numericalDifferentiation.relativeEpsilon = 1e-10 #can be quite small; WHY? simulationSettings.staticSolver.verboseMode = 0 #otherwise, load steps are shown ... simulationSettings.staticSolver.numberOfLoadSteps = 40 simulationSettings.staticSolver.loadStepGeometric = True; simulationSettings.staticSolver.loadStepGeometricRange = 1e4; simulationSettings.staticSolver.adaptiveStep = False simulationSettings.staticSolver.newton.relativeTolerance = 1e-7 #10000 simulationSettings.staticSolver.newton.absoluteTolerance = 1e-10 simulationSettings.staticSolver.newton.maxIterations = 30 #50 for bending into circle simulationSettings.staticSolver.discontinuous.iterationTolerance = 1 simulationSettings.staticSolver.stabilizerODE2term = 2 #may only act on position degrees of freedom if useGraphics: simulationSettings.staticSolver.verboseMode = 1 #otherwise, load steps are shown ... simulationSettings.staticSolver.verboseModeFile = 0 #otherwise, load steps are shown ... simulationSettings.displayStatistics = True exu.StartRenderer() #mbs.WaitForUserToContinue() mbs.SolveStatic(simulationSettings) #183 Newton iterations, 0.114 seconds sol = mbs.systemData.GetODE2Coordinates() n = len(sol) exu.Print('tip displacement: x='+str(sol[n-4])+', y='+str(sol[n-3])) if useGraphics: SC.WaitForRenderEngineStopFlag() exu.StopRenderer() #safely close rendering window! exudynTestGlobals.testError = sol[n-3] - (-0.4842698420787613) #-0.4842698420787613 ; 2021-05-07 (deactivated StaticSolveOldSolver):-0.4842656133238705 #2019-12-17(relTol=1e-7 / up to 7 digits accurate): -0.4842656547442095; 2019-11-22: (-0.4844812763485709) (with relTol=1e-5); y-displacement exudynTestGlobals.testResult = sol[n-3]