.. _examples-ancfmovingrigidbody: ********************** ANCFmovingRigidbody.py ********************** You can view and download this file on Github: `ANCFmovingRigidbody.py `_ .. code-block:: python :linenos: #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ # This is an EXUDYN example # # Details: ANCF ALE Cable2D test including a moving rigid body # # Author: Johannes Gerstmayr # Date: 2019-10-15 # # 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 * SC = exu.SystemContainer() mbs = SC.AddSystem() #err = ANCFCable2D_bending_test(df, SC, mbs) #print(err) #background rect = [-2.5,-2,2.5,1] #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]))) #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #cable: mypi = 3.141592653589793 L=2 # length of ANCF element in m #L=mypi # length of ANCF element in m Em=2.07e11 # Young's modulus of ANCF element in N/m^2 rho=7800 # density of ANCF element in kg/m^3 b=0.002 # width of rectangular ANCF element in m h=0.002 # 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 EI = Em*I rhoA = rho*A EA = Em*A movingMassFactor = 1 #1 = whole cable is moving with vALE speed vALE = 1.3 g=9.81 print("L="+str(L)) print("EI="+str(EI)) print("EA="+str(EA)) print("rhoA="+str(rhoA)) 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 useALE = True if useALE: nALE = mbs.AddNode(NodeGenericODE2(numberOfODE2Coordinates=1, referenceCoordinates=[0], initialCoordinates=[0], initialCoordinates_t=[vALE])) mALE = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nALE, coordinate=0)) #ALE velocity ==> must implement JacobianAE_t in CoordinateConstraint or similar mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mALE], offset=vALE, velocityLevel = True)) # for static computation nc0 = mbs.AddNode(Point2DS1(referenceCoordinates=[0,0,1,0])) nodeList+=[nc0] nElements = 32 lElem = L / nElements for i in range(nElements): nLast = mbs.AddNode(Point2DS1(referenceCoordinates=[lElem*(i+1),0,1,0])) nodeList+=[nLast] if useALE: elem=mbs.AddObject(ALECable2D(physicsLength=lElem, physicsMassPerLength=rhoA, physicsBendingStiffness=EI, physicsAxialStiffness=EA, physicsMovingMassFactor=movingMassFactor, nodeNumbers=[nodeList[i],nodeList[i+1],nALE])) else: elem=mbs.AddObject(Cable2D(physicsLength=lElem, physicsMassPerLength=rhoA, physicsBendingStiffness=EI, physicsAxialStiffness=EA, nodeNumbers=[nc0+i,nc0+i+1])) cableList+=[elem] mBody = mbs.AddMarker(MarkerBodyMass(bodyNumber = elem)) #mbs.AddLoad(Gravity(markerNumber=mBody, loadVector=[0,-g,0])) mANCF0 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = int(nc0)+1*0, coordinate=0)) mANCF1 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = int(nc0)+1*0, coordinate=1)) mANCF2 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = int(nc0)+1*0, coordinate=3)) mANCF3 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nLast, coordinate=1)) #tip constraint mANCF4 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nLast, coordinate=2)) #tip constraint mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF0])) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF1])) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF2])) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF3])) mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF4])) #mANCF3 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nLast, coordinate=1)) #mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF3])) #mANCF4 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nLast, coordinate=0)) #mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF4])) a = 0.1 #y-dim/2 of gondula b = 0.001 #x-dim/2 of gondula massRigid = 12*0.01 inertiaRigid = massRigid/12*(2*a)**2 g = 9.81 # gravity slidingCoordinateInit = lElem*1.5*0 #0.75*L initialLocalMarker = 1 #second element if nElements<2: slidingCoordinateInit /= 3. initialLocalMarker = 0 addRigidBody = True if addRigidBody: #rigid body which slides: graphicsRigid = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[-b,-a,0, b,-a,0, b,a,0, -b,a,0, -b,-a,0]} #drawing of rigid body nRigid = mbs.AddNode(Rigid2D(referenceCoordinates=[slidingCoordinateInit,-a,0], initialVelocities=[vALE,0,0])); oRigid = mbs.AddObject(RigidBody2D(physicsMass=massRigid, physicsInertia=inertiaRigid,nodeNumber=nRigid,visualization=VObjectRigidBody2D(graphicsData= [graphicsRigid]))) markerRigidTop = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[0.,a,0.])) #support point mR2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[ 0.,0.,0.])) #center of mass (for load) mbs.AddLoad(Force(markerNumber = mR2, loadVector = [0, -massRigid*g, 0])) #slidingJoint: addSlidingJoint = False if addSlidingJoint: cableMarkerList = []#list of Cable2DCoordinates markers offsetList = [] #list of offsets counted from first cable element; needed in sliding joint offset = 0 #first cable element has offset 0 for item in cableList: #create markers for cable elements m = mbs.AddMarker(MarkerBodyCable2DCoordinates(bodyNumber = item)) cableMarkerList += [m] offsetList += [offset] offset += lElem #mGroundSJ = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[0.*lElem+0.75*L,0.,0.])) nodeDataSJ = mbs.AddNode(NodeGenericData(initialCoordinates=[initialLocalMarker,slidingCoordinateInit],numberOfDataCoordinates=2)) #initial index in cable list slidingJoint = mbs.AddObject(ObjectJointSliding2D(name='slider', markerNumbers=[markerRigidTop,cableMarkerList[initialLocalMarker]], slidingMarkerNumbers=cableMarkerList, slidingMarkerOffsets=offsetList, nodeNumber=nodeDataSJ)) #ALEslidingJoint: addALESlidingJoint = True if addALESlidingJoint: cableMarkerList = []#list of Cable2DCoordinates markers offsetList = [] #list of offsets counted from first cable element; needed in sliding joint offset = 0 #first cable element has offset 0 for item in cableList: #create markers for cable elements m = mbs.AddMarker(MarkerBodyCable2DCoordinates(bodyNumber = item)) cableMarkerList += [m] offsetList += [offset] offset += lElem #mGroundSJ = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[0.*lElem+0.75*L,0.,0.])) nodeDataSJ = mbs.AddNode(NodeGenericData(initialCoordinates=[initialLocalMarker],numberOfDataCoordinates=1)) #initial index in cable list #nodeODE2ALE = mbs.AddNode(NodeGenericODE2(referenceCoordinates=[0],initialCoordinates=[0],initialCoordinates_t=[0],numberOfODE2Coordinates=1)) #initial index in cable list slidingJoint = mbs.AddObject(ObjectJointALEMoving2D(name='slider', markerNumbers=[markerRigidTop,cableMarkerList[initialLocalMarker]], slidingMarkerNumbers=cableMarkerList, slidingMarkerOffsets=offsetList, slidingOffset= -0*0.5*lElem, nodeNumbers=[nodeDataSJ, nALE])) #print(offsetList) #cStiffness = 1e3 #cDamping = 0.02*cStiffness #useCircleContact = True #if useCircleContact: # 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=[0.65*L,-0.5,0])) # mGroundCircle2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[0.25*L,-0.15,0])) # for i in range(len(cableList)): # #print("cable="+str(cableList[i])) # mCable = mbs.AddMarker(MarkerBodyCable2DShape(bodyNumber=cableList[i], numberOfSegments = nSegments)) # #print("mCable="+str(mCable)) # nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments)) # mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle, mCable], nodeNumber = nodeDataContactCable, # numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=cDamping, # circleRadius = 0.3, offset = 0)) # nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments)) # mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle2, mCable], nodeNumber = nodeDataContactCable, # numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=cDamping, # circleRadius = 0.1, offset = 0)) #mbs.systemData.Info() mbs.Assemble() print(mbs) simulationSettings = exu.SimulationSettings() #takes currently set values or default values #simulationSettings.solutionSettings.coordinatesSolutionFileName = 'ANCFCable2Dbending' + str(nElements) + '.txt' #simulationSettings.outputPrecision = 16 fact = 1500 simulationSettings.timeIntegration.numberOfSteps = fact simulationSettings.timeIntegration.endTime = 0.001*fact simulationSettings.solutionSettings.writeSolutionToFile = True simulationSettings.solutionSettings.solutionWritePeriod = simulationSettings.timeIntegration.endTime/2000 #simulationSettings.solutionSettings.outputPrecision = 4 simulationSettings.displayComputationTime = True simulationSettings.timeIntegration.verboseMode = 1 simulationSettings.timeIntegration.newton.relativeTolerance = 1e-8*10 #10000 simulationSettings.timeIntegration.newton.absoluteTolerance = 1e-10*100 simulationSettings.timeIntegration.newton.useModifiedNewton = False simulationSettings.timeIntegration.newton.maxModifiedNewtonIterations = 8 simulationSettings.timeIntegration.newton.numericalDifferentiation.forAE = True #True should not be used in general, slow&inaccurate! simulationSettings.timeIntegration.newton.numericalDifferentiation.addReferenceCoordinatesToEpsilon = False simulationSettings.timeIntegration.newton.numericalDifferentiation.minimumCoordinateSize = 1.e-3 simulationSettings.timeIntegration.newton.numericalDifferentiation.relativeEpsilon = 1e-8*10 #6.055454452393343e-06*0.0001 #eps^(1/3) simulationSettings.timeIntegration.newton.modifiedNewtonContractivity = 1e8 simulationSettings.timeIntegration.generalizedAlpha.useIndex2Constraints = False simulationSettings.timeIntegration.generalizedAlpha.useNewmark = False simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.4 #0.6 works well simulationSettings.pauseAfterEachStep = False simulationSettings.displayStatistics = True #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" solveDynamic = True if solveDynamic: exu.StartRenderer() mbs.SolveDynamic(simulationSettings) SC.WaitForRenderEngineStopFlag() exu.StopRenderer() #safely close rendering window! else: simulationSettings.staticSolver.newton.numericalDifferentiation.relativeEpsilon = 1e-8 #*100 #can be quite small; WHY? simulationSettings.staticSolver.verboseMode = 2 simulationSettings.staticSolver.numberOfLoadSteps = 20#20*2 simulationSettings.staticSolver.loadStepGeometric = True; simulationSettings.staticSolver.loadStepGeometricRange = 1e3; simulationSettings.staticSolver.newton.relativeTolerance = 1e-5 #1e-5*100 simulationSettings.staticSolver.newton.absoluteTolerance = 1e-10 simulationSettings.staticSolver.newton.maxIterations = 20 #50 for bending into circle simulationSettings.staticSolver.discontinuous.iterationTolerance = 0.1 #simulationSettings.staticSolver.discontinuous.maxIterations = 5 simulationSettings.staticSolver.pauseAfterEachStep = False simulationSettings.staticSolver.stabilizerODE2term = 100*0.0 exu.StartRenderer() mbs.SolveStatic(simulationSettings) sol = mbs.systemData.GetODE2Coordinates() n = len(sol) print('tip displacement: x='+str(sol[n-4])+', y='+str(sol[n-3])) sol_t = mbs.systemData.GetODE2Coordinates_t() print('vALE='+str(sol_t[0])) #print('sol='+str(sol)) print('sol_t='+str(sol_t)) SC.WaitForRenderEngineStopFlag() exu.StopRenderer() #safely close rendering window! # exu.InfoStat(); #class MyDialog: # def __init__(self, parent): # top = self.top = Toplevel(parent) # Label(top, text="Value").pack() # self.e = Entry(top) # self.e.pack(padx=5) # b = Button(top, text="OK", command=self.ok) # b.pack(pady=5) # def ok(self): # #print("value is " + self.e.get()) # exec(self.e.get()) # self.top.destroy() #root = Tk() #Button(root, text="Exudyn").pack() #root.update() #d = MyDialog(root) #root.wait_window(d.top)