ANCFslidingAndALEjointTest.py
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1#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2# This is an EXUDYN example
3#
4# Details: Test model for rigid bodies sliding on cables
5#
6# Author: Andreas Zwölfer, Johannes Gerstmayr
7# Date: 2019-12-18
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
16useGraphics = True #without test
17#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
18#you can erase the following lines and all exudynTestGlobals related operations if this is not intended to be used as TestModel:
19try: #only if called from test suite
20 from modelUnitTests import exudynTestGlobals #for globally storing test results
21 useGraphics = exudynTestGlobals.useGraphics
22except:
23 class ExudynTestGlobals:
24 pass
25 exudynTestGlobals = ExudynTestGlobals()
26#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
27
28SC = exu.SystemContainer()
29mbs = SC.AddSystem()
30
31
32##################################################################################################################################################################
33def AddBodyWithSlidingJoints(mbs,xPositionOfFirstNodes=0,referencePositionOfBodyAlongCable=0,gravityFieldConstant=0):
34
35 a = 0.8*2 #y-dim/2 of Body
36 b = 0.02 #x-dim/2 of Body
37 massRigid = 5000 #moving mass
38 inertiaRigid = massRigid/12*(2*a)**2
39 #rigid body which slides:
40 graphicsRigid1 = GraphicsDataRectangle(-b,-a,b,a) #drawing of rigid body
41 yCOM = a #COM distance to attachment point on suspension rope; in vertical direction
42
43 nRigid = mbs.AddNode(Rigid2D(referenceCoordinates=[xPositionOfFirstNodes+referencePositionOfBodyAlongCable,-yCOM,0]));
44 oRigid = mbs.AddObject(RigidBody2D(physicsMass=massRigid, physicsInertia=inertiaRigid,nodeNumber=nRigid,visualization=VObjectRigidBody2D(graphicsData= [graphicsRigid1])))
45 markerRigidTop=mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[0.,yCOM,0.])) #support point
46 markerRigidTopAle = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[0.,yCOM-offset,0.])) #support point
47
48 if gravityFieldConstant:
49 mR2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[ 0.,0.,0.])) #center of mass (for load)
50 mbs.AddLoad(Force(markerNumber=mR2, loadVector=[0,-massRigid*gravityFieldConstant,0]))
51
52
53 #find index of cable element associated with "referencePositionOfBodyAlongCable"
54 cummulativeLength=0
55 count=0
56 while referencePositionOfBodyAlongCable >= cummulativeLength:
57 cummulativeLength+=mbs.GetObjectParameter(cable2ObjectList[count],'physicsLength')
58 count+=1
59 count+=-1
60
61 #AleSlidingJoint:
62 oAleSlidingJoint=GenerateAleSlidingJoint(mbs,cable1ObjectList,markerRigidTopAle,AleNode=nALE,localMarkerIndexOfStartCable=count,AleSlidingOffset=referencePositionOfBodyAlongCable)[0]
63
64
65 #slidingJoint:
66 oSlidingJoint=GenerateSlidingJoint(mbs,cable2ObjectList,markerRigidTop,localMarkerIndexOfStartCable=count,slidingCoordinateStartPosition=referencePositionOfBodyAlongCable)[0]
67
68 return [oRigid,nRigid, oAleSlidingJoint, oSlidingJoint]
69
70
71#Background:
72rect = [-2,-2,4,2] #xmin,ymin,xmax,ymax
73background0 = {'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
74background1 = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[0,-1,0, 2,-1,0]} #background
75oGround=mbs.AddObject(ObjectGround(referencePosition= [0,0,0]))
76
77L=100 #length of ropes
78gravityFieldConstant=9.81
79complianceFactBend = 1
80complianceFactAxial = 1
81nEl=6 #must be even number
82vALE=0
83offset=0.35 #distance between the two ropes
84offsetCarrier=-0.515 #distance between suspension rope and slack carrier wheel
85
86nGlobalGround = mbs.AddNode(NodePointGround(referenceCoordinates=[0,0,0]))
87mGlobalGround = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nGlobalGround, coordinate=0))
88
89fixANCFRotation = 0
90
91#######################ROPE2 (Carrier rope)########################################################################################################################
92cable2Template=Cable2D(physicsMassPerLength=10, physicsBendingStiffness=50000*complianceFactBend, physicsAxialStiffness=2e8*complianceFactAxial)
93
94[cable2NodeList, cable2ObjectList, suspensionLoadList, cable2NodePositionList, dummy]=GenerateStraightLineANCFCable2D(mbs=mbs,
95 positionOfNode0=[0,0,0], positionOfNode1=[L,0,0], numberOfElements=nEl,
96 cableTemplate=cable2Template, massProportionalLoad=[0,-gravityFieldConstant,0],
97 fixedConstraintsNode0=[1,1,0,fixANCFRotation], fixedConstraintsNode1=[1,1,0,fixANCFRotation])
98##################################################################################################################################################################
99
100
101
102######################ROPE1#######################################################################################################################################
103nALE = mbs.AddNode(NodeGenericODE2(numberOfODE2Coordinates=1, referenceCoordinates=[0], initialCoordinates=[0], initialCoordinates_t=[vALE]))
104mALE = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nALE, coordinate=0)) #ALE velocity marker
105
106cable1Template=ALECable2D(physicsMassPerLength=3, physicsBendingStiffness=4000*complianceFactBend,
107 physicsAxialStiffness=5e7*complianceFactAxial,physicsUseCouplingTerms=False,
108 physicsAddALEvariation=False) #for compatibility with test suite results
109cable1Template.nodeNumbers[2]=nALE
110
111[cable1NodeList, cable1ObjectList, haulageLoadList, cable1NodePositionList, dummy]=GenerateStraightLineANCFCable2D(mbs=mbs,
112 positionOfNode0=[0,-offset,0], positionOfNode1=[L,-offset,0], numberOfElements=nEl,
113 cableTemplate=cable1Template, massProportionalLoad=[0,-gravityFieldConstant,0],
114 fixedConstraintsNode0=[1,1,0,fixANCFRotation], fixedConstraintsNode1=[1,1,0,fixANCFRotation])
115
116cAleConstraint=mbs.AddObject(CoordinateConstraint(markerNumbers=[mGlobalGround,mALE]))
117###################################################################################################################################################################
118
119
120#Slack carrier:
121carrierWheelRadius=0.42/2
122mSuspensionRopeAttachmentNodeX=mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = cable2NodeList[int(nEl/2)], coordinate=0))
123mSuspensionRopeAttachmentNodeY=mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = cable2NodeList[int(nEl/2)], coordinate=1))
124
125graphicsCarrier={'type':'Circle', 'color':[.1,0.1,0.8,1], 'position':[0,0,0], 'radius': carrierWheelRadius}
126nCarrierRigidBody = mbs.AddNode(Rigid2D(referenceCoordinates=[L/2,offsetCarrier-carrierWheelRadius,0]))
127oCarrierRigidBody = mbs.AddObject(RigidBody2D(physicsMass=200, physicsInertia=1,
128 nodeNumber=nCarrierRigidBody,visualization=VObjectRigidBody2D(graphicsData= [graphicsCarrier])))
129
130mCarrierX = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nCarrierRigidBody,coordinate=0))
131mCarrierY = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nCarrierRigidBody,coordinate=1))
132mCarrierRot = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nCarrierRigidBody,coordinate=2))
133
134mbs.AddObject(CoordinateConstraint(markerNumbers=[mSuspensionRopeAttachmentNodeX,mCarrierX]))
135mbs.AddObject(CoordinateConstraint(markerNumbers=[mSuspensionRopeAttachmentNodeY,mCarrierY]))
136mbs.AddObject(CoordinateConstraint(markerNumbers=[mGlobalGround,mCarrierRot]))
137
138#mCarrierWheelLoad = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oCarrierRigidBody, localPosition=[ 0.,0.,0.])) #center of mass (for load)
139#mbs.AddLoad(Force(markerNumber=mConnectionWheelLoad, loadVector=[0,-CarrierMass*gravityFieldConstant,0]))
140
141nSegments = 4 #number of contact segments; must be consistent between nodedata and contact element
142useFriction = True
143nFactFriction = 1
144if useFriction: nFactFriction = 3
145
146initialGapList = [0.1]*(nSegments*nFactFriction) #initial gap of 0.1
147cStiffness = 1e7
148mContactCarrier=mbs.AddMarker(MarkerBodyRigid(bodyNumber = oCarrierRigidBody))
149
150
151for i in cable1ObjectList:
152 mContactCable = mbs.AddMarker(MarkerBodyCable2DShape(bodyNumber=i, numberOfSegments = nSegments))
153 nodeDataContactCable = mbs.AddNode(NodeGenericData(initialCoordinates=initialGapList,numberOfDataCoordinates=nSegments*nFactFriction))
154 if useFriction:
155 mbs.AddObject(ObjectContactFrictionCircleCable2D(markerNumbers=[mContactCarrier, mContactCable],
156 nodeNumber = nodeDataContactCable, numberOfContactSegments=nSegments,
157 contactStiffness = cStiffness, circleRadius = carrierWheelRadius))
158 else:
159 mbs.AddObject(ObjectContactCircleCable2D(markerNumbers=[mContactCarrier, mContactCable],
160 nodeNumber = nodeDataContactCable, numberOfContactSegments=nSegments,
161 contactStiffness = cStiffness, circleRadius = carrierWheelRadius, offset = 0))
162
163
164
165#Add Bodys
166cRigidBodyRotList=[]
167cRigidBodyTranslationXlist=[]
168cRigidBodyTranslationYlist=[]
169distanceBetweenBodys=32
170numberOfBodys=2
171positionOfBody=0
172for i in range(numberOfBodys):
173
174 #Add Body
175 [oRigid,nRigid,oAleSlidingJoint,oSlidingJoint]=AddBodyWithSlidingJoints(mbs,xPositionOfFirstNodes=0,referencePositionOfBodyAlongCable=positionOfBody,gravityFieldConstant=gravityFieldConstant)
176 mbs.SetObjectParameter(oSlidingJoint, 'classicalFormulation', False) #test model computed with new sliding joint formulation
177
178 #fix rotation of rigid body
179 mRigidBodyRot = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber = nRigid, coordinate=2)) #add rigid body marker
180 cRigidBodyRot = mbs.AddObject(CoordinateConstraint(markerNumbers=[mGlobalGround,mRigidBodyRot]))
181 cRigidBodyRotList+=[cRigidBodyRot]
182
183 #add damper for rotation of rigid body
184 mbs.AddObject(CoordinateSpringDamper(markerNumbers=[mGlobalGround,mRigidBodyRot],damping = 1e6, visualization=VObjectConnectorCoordinateSpringDamper(show=False)))
185
186 positionOfBody+=distanceBetweenBodys
187
188
189#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
190# Assemble multibody system
191#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
192mbs.Assemble()
193#exu.Print(mbs)
194
195#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
196# Simualtion settings:
197#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
198simulationSettings = exu.SimulationSettings()
199#simulationSettings.staticSolver.loadStepGeometric = True
200#simulationSettings.staticSolver.adaptiveStep = False
201simulationSettings.staticSolver.numberOfLoadSteps=10
202#simulationSettings.staticSolver.loadStepGeometricRange = 100
203simulationSettings.staticSolver.newton.relativeTolerance = 1e-7 #with this error tolerance, the adaptive step selection needs 4 steps
204
205#simulationSettings.staticSolver.verboseMode=1
206#simulationSettings.staticSolver.verboseModeFile=2
207simulationSettings.staticSolver.stabilizerODE2term = 2
208
209
210SC.visualizationSettings.general.circleTiling = 64
211SC.visualizationSettings.nodes.defaultSize=0.125
212SC.visualizationSettings.contour.outputVariable = exu.OutputVariableType.Displacement
213SC.visualizationSettings.contour.outputVariableComponent = 1 # plot y-component
214SC.visualizationSettings.contact.contactPointsDefaultSize = .005
215SC.visualizationSettings.connectors.showContact = True
216
217
218if useGraphics:
219 exu.StartRenderer()
220
221#get initial velocities
222vInit = mbs.systemData.GetODE2Coordinates_t(configuration = exu.ConfigurationType.Initial)
223
224#start static calculation
225mbs.SolveStatic(simulationSettings)
226
227#++++++++++++++++++++++++++++++++++++++++
228#compute error for test suite:
229ltgCable = mbs.systemData.GetObjectLTGODE2(cable1ObjectList[int(len(cable1ObjectList)/2)])
230nc = ltgCable[1] #vertical displacement
231exu.Print("select cable coordinate", nc)
232sol = mbs.systemData.GetODE2Coordinates();
233uStatic = sol[nc]; #y-displacement of first node of four bar mechanism
234exu.Print('static solution of cable1 =',uStatic)
235exudynTestGlobals.testError = uStatic - (-2.1973218891272532) #before 2023-05-01 (new loads jacobian): -2.1973218869310713 #before 2022-03-09 (old ObjectContactFrictionCircleCable2D): -2.197321886974786 2020-03-05(corrected Cable2DshapeMarker): -2.197321886974786 #2019-12-26: 2.1973218859908146
236exudynTestGlobals.testResult = uStatic
237
238#++++++++++++++++++++++++++++++++++++++++
239#store solution for next computation
240u = mbs.systemData.GetODE2Coordinates()
241data = mbs.systemData.GetDataCoordinates()
242
243#Add drive via ALE:
244def userLoadDriveAle(mbs, t, load):
245 #if t < 1:
246 return t*50000*5
247 #else: return 0
248
249mbs.AddLoad(LoadCoordinate(markerNumber = mALE, loadUserFunction=userLoadDriveAle))
250mbs.Assemble() #because of new load
251
252#++++++++++++++++++++++++++++++++++++++++
253#resuse old solution
254mbs.systemData.SetODE2Coordinates(u,configuration = exu.ConfigurationType.Initial)
255mbs.systemData.SetODE2Coordinates_t(vInit,configuration = exu.ConfigurationType.Initial)
256mbs.systemData.SetDataCoordinates(data,configuration = exu.ConfigurationType.Initial)
257
258
259
260# remove rigid body motion constraints for dynamic analysis
261for item in cRigidBodyRotList:
262 mbs.SetObjectParameter(item, 'activeConnector', False)
263mbs.SetObjectParameter(cAleConstraint, 'activeConnector', False)
264
265
266solveDynamic = True
267if solveDynamic:
268 # time related settings:
269 steps=400
270 tend=0.8
271 h=tend/steps
272 SC.visualizationSettings.openGL.lineWidth = 2
273 simulationSettings.timeIntegration.numberOfSteps = steps
274 simulationSettings.timeIntegration.endTime = tend
275 simulationSettings.timeIntegration.generalizedAlpha.useIndex2Constraints = True
276 simulationSettings.timeIntegration.generalizedAlpha.useNewmark = simulationSettings.timeIntegration.generalizedAlpha.useIndex2Constraints
277 simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.3
278 simulationSettings.timeIntegration.verboseMode = 1
279 simulationSettings.displayStatistics = True
280
281 mbs.SolveDynamic(simulationSettings)
282
283if useGraphics:
284 #SC.WaitForRenderEngineStopFlag()
285 exu.StopRenderer() #safely close rendering window!
286
287
288sol = mbs.systemData.GetODE2Coordinates();
289uDynamic = sol[nc]; #y-displacement of first node of four bar mechanism
290exu.Print('dynamic solution of cable1 =',uDynamic)
291
292exudynTestGlobals.testError += uDynamic - (-2.2290865056280076) #before 2023-05-01 (loads jacobian): -2.229086503625397 #before 2022-12-25(resolved BUG 1274): -2.229081157258582; before 2022-03-09 (old ObjectContactFrictionCircleCable2D) : (-2.2290811574753953) #2020-03-05(corrected Cable2DshapeMarker): -2.2290811574753953 #2019-12-26: -2.2290811558815617; 2019-12-18: -2.229126333291627
293exudynTestGlobals.testResult += uDynamic
294
295exu.Print('result of ANCFslidingAndALEjointTest=',exudynTestGlobals.testResult)