ANCFcontactCircle2.py

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  1#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  ANCF Cable2D contact test
  5#
  6# Author:   Johannes Gerstmayr
  7# Date:     2019-10-01
  8#
  9# 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.
 10#
 11#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 12
 13import exudyn as exu
 14from exudyn.utilities import *
 15
 16
 17SC = exu.SystemContainer()
 18mbs = SC.AddSystem()
 19
 20L=2                     # length of ANCF element in m
 21pCircle = [0.65*L,-0.5,0]
 22pCircle2 =  [0.25*L,-0.15,0]
 23circleRadius=0.3
 24circleRadius2=0.1
 25
 26#background
 27rect = [-0.5,-1,2.5,1] #xmin,ymin,xmax,ymax
 28background1 = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[0,-1,0, 2,-1,0]} #background
 29
 30
 31background  = [GraphicsDataRectangle(-0.5,-1,2.5,1, color=color4blue)]
 32background += [GraphicsDataLine([[0,-1,0], [2,-1,0]], color=color4green)]
 33background += [GraphicsDataCircle(point=pCircle, radius = circleRadius-0.002, color=color4blue)] #not necessary, as it is drawn by connector
 34background += [GraphicsDataCircle(point=pCircle2, radius = circleRadius2-0.002, color=color4blue)] #not necessary, as it is drawn by connector
 35background += [GraphicsDataText(point=[0.,0.2,0], text = 'ANCF contact with circle', color=color4black)]
 36
 37oGround=mbs.AddObject(ObjectGround(referencePosition= [0,0,0], visualization=VObjectGround(graphicsData= background)))
 38
 39
 40#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 41#cable:
 42mypi = 3.141592653589793
 43
 44#L=mypi                 # length of ANCF element in m
 45E=2.07e11               # Young's modulus of ANCF element in N/m^2
 46rho=7800                # density of ANCF element in kg/m^3
 47b=0.001                 # width of rectangular ANCF element in m
 48h=0.001                 # height of rectangular ANCF element in m
 49A=b*h                   # cross sectional area of ANCF element in m^2
 50I=b*h**3/12             # second moment of area of ANCF element in m^4
 51f=3*E*I/L**2            # tip load applied to ANCF element in N
 52
 53print("load f="+str(f))
 54print("EI="+str(E*I))
 55
 56nGround = mbs.AddNode(NodePointGround(referenceCoordinates=[0,0,0])) #ground node for coordinate constraint
 57mGround = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nGround, coordinate=0)) #Ground node ==> no action
 58
 59cableList=[]        #for cable elements
 60nodeList=[]  #for nodes of cable
 61markerList=[]       #for nodes
 62nc0 = mbs.AddNode(Point2DS1(referenceCoordinates=[0,0,1,0]))
 63nodeList+=[nc0]
 64nElements = 8*4 #8,16,32,64
 65lElem = L / nElements
 66for i in range(nElements):
 67    nLast = mbs.AddNode(Point2DS1(referenceCoordinates=[lElem*(i+1),0,1,0]))
 68    nodeList+=[nLast]
 69    elem=mbs.AddObject(Cable2D(physicsLength=lElem, physicsMassPerLength=rho*A,
 70                               physicsBendingStiffness=E*I, physicsAxialStiffness=E*A*0.1,
 71                               nodeNumbers=[int(nc0)+i,int(nc0)+i+1]))
 72    cableList+=[elem]
 73
 74mANCF0 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nc0, coordinate=0))
 75mANCF1 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nc0, coordinate=1))
 76mANCF2 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nc0, coordinate=3))
 77
 78mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF0]))
 79mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF1]))
 80mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCF2]))
 81
 82#add gravity:
 83markerList=[]
 84for i in range(len(nodeList)):
 85    m = mbs.AddMarker(MarkerNodePosition(nodeNumber=nodeList[i]))
 86    markerList+=[m]
 87    fact = 1 #add (half) weight of two elements to node
 88    if (i==0) | (i==len(nodeList)-1): fact = 0.5 # first and last node only weighted half
 89    mbs.AddLoad(Force(markerNumber = m, loadVector = [0, -400*rho*A*fact*lElem, 0])) #will be changed in load steps
 90
 91#mANCFend = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nodeList[-1], coordinate=1)) #last marker
 92#mbs.AddObject(CoordinateConstraint(markerNumbers=[mGround,mANCFend]))
 93
 94#mGroundTip = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[L,0,0]))
 95#mbs.AddObject(CartesianSpringDamper(markerNumbers=[mGroundTip,markerList[-1]], stiffness=[10,10,10], damping=[0.1,0.1,0.1]))
 96
 97#mGroundTip2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=[L,0.2,0]))
 98#mbs.AddObject(SpringDamper(markerNumbers=[mGroundTip2,markerList[-1]], stiffness=0.1, referenceLength=0.2))
 99
100#mANCFLast = mbs.AddMarker(MarkerNodePosition(nodeNumber=nLast)) #force
101#mbs.AddLoad(Force(markerNumber = mANCFLast, loadVector = [0, -1e8, 0])) #will be changed in load steps
102
103#mANCFrigid = mbs.AddMarker(MarkerBodyRigid(bodyNumber=elem, localPosition=[lElem,0,0])) #local position L = beam tip
104#mbs.AddLoad(Torque(markerNumber = mANCFrigid, loadVector = [0, 0, E*I*1*mypi]))
105
106#mANCFnode = mbs.AddMarker(MarkerNodeRigid(nodeNumber=nLast)) #local position L = beam tip
107#mbs.AddLoad(Torque(markerNumber = mANCFnode, loadVector = [0, 0, 3*E*I*1*mypi]))
108
109cStiffness = 1e3
110cDamping = 0.02*cStiffness*0
111useContact = False
112if useContact:
113    tipContact = False
114    if tipContact:
115        nodeData = mbs.AddNode(NodeGenericData(initialCoordinates=[0],numberOfDataCoordinates=1))
116        mbs.AddObject(ObjectContactCoordinate(markerNumbers=[mGround, mANCFend],nodeNumber = nodeData, contactStiffness = cStiffness, contactDamping=cDamping, offset = -0.8))
117    else:
118        for i in range(len(nodeList)):
119            mNC = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nodeList[i], coordinate=1))
120            nodeData = mbs.AddNode(NodeGenericData(initialCoordinates=[1],numberOfDataCoordinates=1)) #start with gap!
121            mbs.AddObject(ObjectContactCoordinate(markerNumbers=[mGround, mNC], nodeNumber = nodeData, contactStiffness = cStiffness, contactDamping=cDamping, offset = -1))
122
123useCircleContact = True
124if useCircleContact:
125    nSegments = 8 #4; number of contact segments; must be consistent between nodedata and contact element
126    initialGapList = [0.1]*nSegments #initial gap of 0.1
127    mGroundCircle = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=pCircle))
128    mGroundCircle2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround, localPosition=pCircle2))
129
130    #mCable = mbs.AddMarker(MarkerBodyCable2DShape(bodyNumber=elem, numberOfSegments = nSegments))
131    #nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments))
132    #mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle, mCable], nodeNumber = nodeDataContactCable,
133    #                                         numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=cDamping,
134    #                                         circleRadius = 0.4, offset = 0))
135    for i in range(len(cableList)):
136        #print("cable="+str(cableList[i]))
137        mCable = mbs.AddMarker(MarkerBodyCable2DShape(bodyNumber=cableList[i], numberOfSegments = nSegments))
138        #print("mCable="+str(mCable))
139        nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments))
140        mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle, mCable], nodeNumber = nodeDataContactCable,
141                                                 numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=cDamping,
142                                                 circleRadius = circleRadius, offset = 0))
143        nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments))
144        mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mGroundCircle2, mCable], nodeNumber = nodeDataContactCable,
145                                                 numberOfContactSegments=nSegments, contactStiffness = cStiffness, contactDamping=cDamping,
146                                                 circleRadius = circleRadius2, offset = 0))
147
148
149#mbs.systemData.Info()
150
151mbs.Assemble()
152print(mbs)
153
154simulationSettings = exu.SimulationSettings() #takes currently set values or default values
155#simulationSettings.solutionSettings.coordinatesSolutionFileName = 'ANCFCable2Dbending' + str(nElements) + '.txt'
156
157fact = 10000
158simulationSettings.timeIntegration.numberOfSteps = 1*fact
159simulationSettings.timeIntegration.endTime = 0.001*fact
160simulationSettings.solutionSettings.writeSolutionToFile = True
161simulationSettings.solutionSettings.solutionWritePeriod = simulationSettings.timeIntegration.endTime/fact
162#simulationSettings.solutionSettings.outputPrecision = 4
163simulationSettings.displayComputationTime = True
164simulationSettings.timeIntegration.verboseMode = 1
165
166simulationSettings.timeIntegration.newton.relativeTolerance = 1e-8*10 #10000
167simulationSettings.timeIntegration.newton.absoluteTolerance = 1e-10*100
168
169simulationSettings.timeIntegration.newton.useModifiedNewton = False
170simulationSettings.timeIntegration.newton.maxModifiedNewtonIterations = 5
171simulationSettings.timeIntegration.newton.numericalDifferentiation.minimumCoordinateSize = 1
172simulationSettings.timeIntegration.newton.numericalDifferentiation.relativeEpsilon = 6.055454452393343e-06*0.1 #eps^(1/3)
173simulationSettings.timeIntegration.newton.modifiedNewtonContractivity = 1e8
174simulationSettings.timeIntegration.generalizedAlpha.useIndex2Constraints = False
175simulationSettings.timeIntegration.generalizedAlpha.useNewmark = False
176simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.6 #0.6 works well
177simulationSettings.displayStatistics = True
178
179#SC.visualizationSettings.nodes.showNumbers = True
180SC.visualizationSettings.bodies.showNumbers = False
181#SC.visualizationSettings.connectors.showNumbers = True
182SC.visualizationSettings.nodes.defaultSize = 0.01
183SC.visualizationSettings.markers.defaultSize = 0.01
184SC.visualizationSettings.connectors.defaultSize = 0.01
185SC.visualizationSettings.contact.contactPointsDefaultSize = 0.005
186SC.visualizationSettings.connectors.showContact = 1
187SC.visualizationSettings.general.circleTiling = 64
188
189simulationSettings.solutionSettings.solutionInformation = "ANCF cable with imposed curvature or applied tip force/torque"
190
191solveDynamic = False
192if solveDynamic:
193    exu.StartRenderer()
194
195    mbs.SolveDynamic(simulationSettings)
196
197    SC.WaitForRenderEngineStopFlag()
198    exu.StopRenderer() #safely close rendering window!
199
200else:
201    simulationSettings.staticSolver.newton.numericalDifferentiation.relativeEpsilon = 1e-10*100 #can be quite small; WHY?
202    simulationSettings.staticSolver.newton.numericalDifferentiation.doSystemWideDifferentiation = False
203    simulationSettings.staticSolver.verboseMode = 1
204    simulationSettings.staticSolver.numberOfLoadSteps  = 20*2
205    simulationSettings.staticSolver.loadStepGeometric = True;
206    simulationSettings.staticSolver.loadStepGeometricRange = 5e3;
207
208    simulationSettings.staticSolver.newton.relativeTolerance = 1e-5*100 #10000
209    simulationSettings.staticSolver.newton.absoluteTolerance = 1e-10
210    simulationSettings.staticSolver.newton.maxIterations = 30 #50 for bending into circle
211
212    simulationSettings.staticSolver.discontinuous.iterationTolerance = 0.1
213    #simulationSettings.staticSolver.discontinuous.maxIterations = 5
214    simulationSettings.pauseAfterEachStep = False
215    simulationSettings.staticSolver.stabilizerODE2term = 50
216
217    exu.StartRenderer()
218
219    mbs.WaitForUserToContinue()
220    mbs.SolveStatic(simulationSettings)
221
222    #sol = mbs.systemData.GetODE2Coordinates()
223    #n = len(sol)
224    #print('tip displacement: x='+str(sol[n-4])+', y='+str(sol[n-3]))
225
226    SC.WaitForRenderEngineStopFlag()
227    exu.StopRenderer() #safely close rendering window!
228
229# exu.InfoStat();