NGsolveCraigBampton.py

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  1#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  Test for Hurty-Craig-Bampton modes using a simple flexible pendulum meshed with Netgen
  5#
  6# Author:   Johannes Gerstmayr
  7# Date:     2021-04-20
  8# Update:   2022-07-11: runs now with pip installed ngsolve on Python 3.10
  9#
 10# 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.
 11#
 12#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 13
 14
 15import exudyn as exu
 16from exudyn.utilities import * #includes itemInterface and rigidBodyUtilities
 17import exudyn.graphics as graphics #only import if it does not conflict
 18from exudyn.FEM import *
 19
 20SC = exu.SystemContainer()
 21mbs = SC.AddSystem()
 22
 23import numpy as np
 24import time
 25
 26import numpy as np
 27
 28useGraphics = True
 29fileName = 'testData/netgenBrick' #for load/save of FEM data
 30
 31
 32
 33#%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
 34#netgen/meshing part:
 35fem = FEMinterface()
 36#standard:
 37a = 0.025 #height/width of beam
 38b = a
 39h = 0.5*a
 40L = 1     #Length of beam
 41nModes = 8
 42
 43# #coarse1:
 44# a = 0.025 #height/width of beam
 45# b = a
 46# h = a
 47# L = 1     #Length of beam
 48# nModes = 2
 49
 50#plate:
 51# a = 0.025 #height/width of beam
 52# b = 0.4
 53# L = 1     #Length of beam
 54# h = 0.6*a
 55# nModes = 40
 56
 57#for saving:
 58# h = 1.25*a
 59
 60
 61rho = 1000
 62Emodulus=1e7*10
 63nu=0.3
 64meshCreated = False
 65meshOrder = 1 #use order 2 for higher accuracy, but more unknowns
 66
 67#%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
 68if True: #needs netgen/ngsolve to be installed with pip install; to compute mesh, see e.g.: https://github.com/NGSolve/ngsolve/releases
 69
 70    import ngsolve as ngs
 71    from netgen.meshing import *
 72    from netgen.csg import *
 73
 74    geo = CSGeometry()
 75
 76    block = OrthoBrick(Pnt(0,-a,-b),Pnt(L,a,b))
 77    geo.Add(block)
 78
 79    #Draw (geo)
 80
 81    mesh = ngs.Mesh( geo.GenerateMesh(maxh=h))
 82    mesh.Curve(1)
 83
 84    if False: #set this to true, if you want to visualize the mesh inside netgen/ngsolve
 85        import netgen.gui #this starts netgen gui; Press button "Visual" and activate "Auto-redraw after (sec)"; Then select "Mesh"
 86
 87    meshCreated = True
 88    #%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
 89    #Use fem to import FEM model and create FFRFreducedOrder object
 90    [bfM, bfK, fes] = fem.ImportMeshFromNGsolve(mesh, density=rho,
 91                                                youngsModulus=Emodulus, poissonsRatio=nu,
 92                                                meshOrder=meshOrder)
 93    if h == 1.25*a:
 94        fem.SaveToFile(fileName)
 95
 96#%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
 97#compute Hurty-Craig-Bampton modes
 98if not meshCreated: #now import mesh as mechanical model to EXUDYN
 99    fem.LoadFromFile(fileName)
100
101if True:
102    pLeft = [0,-a,-b]
103    pRight = [L,-a,-b]
104    nTip = fem.GetNodeAtPoint(pRight) #tip node (do not use midpoint, as this may not be a mesh node ...)
105    #print("nMid=",nMid)
106    nodesLeftPlane = fem.GetNodesInPlane(pLeft, [-1,0,0])
107    # lenNodesLeftPlane = len(nodesLeftPlane)
108    # weightsLeftPlane = np.array((1./lenNodesLeftPlane)*np.ones(lenNodesLeftPlane))
109    weightsLeftPlane = fem.GetNodeWeightsFromSurfaceAreas(nodesLeftPlane)
110
111    nodesRightPlane = fem.GetNodesInPlane(pRight, [-1,0,0])
112    # lenNodesRightPlane = len(nodesRightPlane)
113    # weightsRightPlane = np.array((1./lenNodesRightPlane)*np.ones(lenNodesRightPlane))
114    weightsRightPlane = fem.GetNodeWeightsFromSurfaceAreas(nodesRightPlane)
115
116    #boundaryList = [nodesLeftPlane, nodesRightPlane] #second boudary (right plane) not needed ...
117    boundaryList = [nodesLeftPlane]
118
119    print("nNodes=",fem.NumberOfNodes())
120
121    print("compute HCB modes... ")
122    start_time = time.time()
123    fem.ComputeHurtyCraigBamptonModes(boundaryNodesList=boundaryList,
124                                  nEigenModes=nModes,
125                                  useSparseSolver=True,
126                                  computationMode = HCBstaticModeSelection.RBE2)
127    print("HCB modes needed %.3f seconds" % (time.time() - start_time))
128
129    #alternatives:
130    #fem.ComputeEigenModesWithBoundaryNodes(boundaryNodes=nodesLeftPlane, nEigenModes=nModes, useSparseSolver=False)
131    #fem.ComputeEigenmodes(nModes, excludeRigidBodyModes = 6, useSparseSolver = True)
132    #print("eigen freq.=", fem.GetEigenFrequenciesHz())
133
134
135    #%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
136    #compute stress modes for postprocessing (inaccurate for coarse meshes, just for visualization):
137    if False:
138        mat = KirchhoffMaterial(Emodulus, nu, rho)
139        varType = exu.OutputVariableType.StressLocal
140        #varType = exu.OutputVariableType.StrainLocal
141        print("ComputePostProcessingModes ... (may take a while)")
142        start_time = time.time()
143        if True: #faster with ngsolve; requires fes
144            fem.ComputePostProcessingModesNGsolve(fes, material=mat,
145                                           outputVariableType=varType)
146        else:
147            fem.ComputePostProcessingModes(material=mat,
148                                            outputVariableType=varType)
149        print("   ... needed %.3f seconds" % (time.time() - start_time))
150        SC.visualizationSettings.contour.reduceRange=False
151        SC.visualizationSettings.contour.outputVariable = varType
152        SC.visualizationSettings.contour.outputVariableComponent = 0 #x-component
153    else:
154        SC.visualizationSettings.contour.outputVariable = exu.OutputVariableType.DisplacementLocal
155        SC.visualizationSettings.contour.outputVariableComponent = 1
156
157    #%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
158    print("create CMS element ...")
159    cms = ObjectFFRFreducedOrderInterface(fem)
160
161    objFFRF = cms.AddObjectFFRFreducedOrder(mbs, positionRef=[0,0,0],
162                                                  initialVelocity=[0,0,0],
163                                                  initialAngularVelocity=[0,0,0],
164                                                  gravity=[0,-9.81,0],
165                                                  color=[0.1,0.9,0.1,1.],
166                                                  )
167
168    #%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
169    #animate modes
170    if False:
171        from exudyn.interactive import AnimateModes
172        mbs.Assemble()
173        SC.visualizationSettings.nodes.show = False
174        SC.visualizationSettings.openGL.showFaceEdges = True
175        SC.visualizationSettings.openGL.multiSampling=4
176        #SC.visualizationSettings.window.renderWindowSize = [1600,1080]
177        # SC.visualizationSettings.contour.outputVariable = exu.OutputVariableType.DisplacementLocal
178        # SC.visualizationSettings.contour.outputVariableComponent = 0 #component
179
180
181        #%%+++++++++++++++++++++++++++++++++++++++
182        #animate modes of ObjectFFRFreducedOrder (only needs generic node containing modal coordinates)
183        SC.visualizationSettings.general.autoFitScene = False #otherwise, model may be difficult to be moved
184
185        nodeNumber = objFFRF['nGenericODE2'] #this is the node with the generalized coordinates
186        AnimateModes(SC, mbs, nodeNumber)
187        import sys
188        sys.exit()
189
190
191    #%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
192    #add markers and joints
193    nodeDrawSize = 0.0025 #for joint drawing
194
195
196    mRB = mbs.AddMarker(MarkerNodeRigid(nodeNumber=objFFRF['nRigidBody']))
197    oGround = mbs.AddObject(ObjectGround(referencePosition= [0,0,0]))
198
199    if True:
200        leftMidPoint = [0,0,0]
201
202        mGround = mbs.AddMarker(MarkerBodyRigid(bodyNumber=oGround, localPosition=leftMidPoint))
203
204        mLeft = mbs.AddMarker(MarkerSuperElementRigid(bodyNumber=objFFRF['oFFRFreducedOrder'],
205                                                      meshNodeNumbers=np.array(nodesLeftPlane), #these are the meshNodeNumbers
206                                                      weightingFactors=weightsLeftPlane))
207        mbs.AddObject(GenericJoint(markerNumbers=[mGround, mLeft],
208                                   constrainedAxes = [1,1,1,1,1,1*0],
209                                   visualization=VGenericJoint(axesRadius=0.1*a, axesLength=0.1*a)))
210
211    #%%+++++++++++++++++++++++++++++++++++++++++++++++++++++
212    fileDir = 'solution/'
213    sensTipDispl = mbs.AddSensor(SensorSuperElement(bodyNumber=objFFRF['oFFRFreducedOrder'], meshNodeNumber=nTip, #meshnode number!
214                             fileName=fileDir+'nMidDisplacementCMS'+str(nModes)+'Test.txt',
215                             outputVariableType = exu.OutputVariableType.Displacement))
216
217    mbs.Assemble()
218
219    simulationSettings = exu.SimulationSettings()
220
221    SC.visualizationSettings.nodes.defaultSize = nodeDrawSize
222    SC.visualizationSettings.nodes.drawNodesAsPoint = False
223    SC.visualizationSettings.connectors.defaultSize = 2*nodeDrawSize
224
225    SC.visualizationSettings.nodes.show = False
226    SC.visualizationSettings.nodes.showBasis = True #of rigid body node of reference frame
227    SC.visualizationSettings.nodes.basisSize = 0.12
228    SC.visualizationSettings.bodies.deformationScaleFactor = 1 #use this factor to scale the deformation of modes
229
230    SC.visualizationSettings.openGL.showFaceEdges = True
231    SC.visualizationSettings.openGL.showFaces = True
232
233    SC.visualizationSettings.sensors.show = True
234    SC.visualizationSettings.sensors.drawSimplified = False
235    SC.visualizationSettings.sensors.defaultSize = 0.01
236    SC.visualizationSettings.markers.drawSimplified = False
237    SC.visualizationSettings.markers.show = False
238    SC.visualizationSettings.markers.defaultSize = 0.01
239
240    SC.visualizationSettings.loads.drawSimplified = False
241
242
243    simulationSettings.solutionSettings.solutionInformation = "ObjectFFRFreducedOrder test"
244
245    h=1e-3
246    tEnd = 4
247
248    simulationSettings.timeIntegration.numberOfSteps = int(tEnd/h)
249    simulationSettings.timeIntegration.endTime = tEnd
250    # simulationSettings.solutionSettings.writeSolutionToFile = False
251    simulationSettings.timeIntegration.verboseMode = 1
252    #simulationSettings.timeIntegration.verboseModeFile = 3
253    simulationSettings.timeIntegration.newton.useModifiedNewton = True
254
255    simulationSettings.solutionSettings.sensorsWritePeriod = h
256
257    simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.8
258    #simulationSettings.displayStatistics = True
259    simulationSettings.displayComputationTime = True
260
261    #create animation:
262    # simulationSettings.solutionSettings.recordImagesInterval = 0.005
263    # SC.visualizationSettings.exportImages.saveImageFileName = "animation/frame"
264    SC.visualizationSettings.window.renderWindowSize=[1920,1080]
265    SC.visualizationSettings.openGL.multiSampling = 4
266
267    useGraphics=True
268    if True:
269        if useGraphics:
270            SC.visualizationSettings.general.autoFitScene=False
271
272            SC.renderer.Start()
273            if 'renderState' in exu.sys: SC.renderer.SetState(exu.sys['renderState']) #load last model view
274
275            SC.renderer.DoIdleTasks() #press space to continue
276
277        if True:
278            mbs.SolveDynamic(#solverType=exu.DynamicSolverType.TrapezoidalIndex2,
279                              simulationSettings=simulationSettings)
280        else:
281            mbs.SolveStatic(simulationSettings=simulationSettings)
282
283        uTip = mbs.GetSensorValues(sensTipDispl)[1]
284        print("nModes=", nModes, ", tip displacement=", uTip)
285
286        if False:
287            # SC.visualizationSettings.exportImages.saveImageFileName = "images/test"
288            SC.visualizationSettings.exportImages.saveImageFormat = "TXT"
289            SC.visualizationSettings.exportImages.saveImageAsTextTriangles=True
290            SC.renderer.RedrawAndSaveImage() #uses default filename
291
292            from exudyn.plot import LoadImage, PlotImage
293            data = LoadImage('images/frame00000.txt', trianglesAsLines=True)
294            #PlotImage(data)
295            PlotImage(data, HT=HomogeneousTransformation(RotationMatrixZ(0.*pi)@RotationMatrixX(0.*pi), [0,0,0]), lineWidths=0.5, lineStyles='-',
296                      triangleEdgeColors='b', triangleEdgeWidths=0.1, title='', closeAll=True, plot3D=True)
297            # PlotImage(data, HT=HomogeneousTransformation(RotationMatrixZ(0.5*pi)@RotationMatrixX(0.5*pi), [0,0,0]), lineWidths=0.5, title='', closeAll=True, fileName='images/test.pdf')
298
299
300        if useGraphics:
301            SC.renderer.DoIdleTasks()
302            SC.renderer.Stop() #safely close rendering window!
303
304
305        #mbs.SolutionViewer()
306
307
308#%%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
309#convergence of static tip-displacement with free-free eigenmodes:
310# nModes= 2 , tip displacement= -0.020705764289813425
311# nModes= 4 , tip displacement= -0.028232935031474123
312# nModes= 8 , tip displacement= -0.03462347289851485
313# nModes= 12 , tip displacement= -0.03744041447559639
314# nModes= 20 , tip displacement= -0.0421200606030284
315# nModes= 32 , tip displacement= -0.045122957364252446
316# nModes= 50 , tip displacement= -0.04711202668188235
317# nModes= 80 , tip displacement= -0.049164046183158706
318# nModes= 120 , tip displacement= -0.050065649361566426
319# nModes= 200 , tip displacement= -0.05054314003738750
320#with correct boundary conditions:
321#nModes= 20 , tip displacement= -0.05254089450183475
322#with Hurty-Craig-Bampton RBE2 boundaries:
323#nModes= 2 , tip displacement= -0.05254074496775043
324#nModes= 8 , tip displacement= -0.05254074496762861