geometricallyExactBeamTest.py

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  1#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  Test models for GeometricallyExactBeam (2-node shear deformable beam,
  5#           Lie group formulation for work of elastic forces);
  6#           test models: cantilever beam with tip force and torque
  7#
  8# Author:   Johannes Gerstmayr
  9# Date:     2023-04-05
 10#
 11# 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.
 12#
 13#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 14
 15import exudyn as exu
 16from exudyn.utilities import *
 17
 18import numpy as np
 19
 20useGraphics = True #without test
 21#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 22#you can erase the following lines and all exudynTestGlobals related operations if this is not intended to be used as TestModel:
 23try: #only if called from test suite
 24    from modelUnitTests import exudynTestGlobals #for globally storing test results
 25    useGraphics = exudynTestGlobals.useGraphics
 26except:
 27    class ExudynTestGlobals:
 28        pass
 29    exudynTestGlobals = ExudynTestGlobals()
 30#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 31
 32SC = exu.SystemContainer()
 33mbs = SC.AddSystem()
 34
 35compute2D = False
 36compute3D = True
 37
 38#test examples
 39#2011 MUBO, Nachbagauer Pechstein Irschik Gerstmayr (2D)
 40#2013 CND, Nachbagauer Gruber Gerstmayr (static, 3D); "Structural and Continuum Mechanics Approaches for a 3D Shear Deformable ANCF Beam Finite Element: Application to Static and Linearized Dynamic Examples"
 41### not yet: 2013 CND, Nachbagauer Gerstmayr (dynamic, 3D)
 42cases = ['CantileverLinear2011', 'Cantilever2011', 'GeneralBending2013', 'PrincetonBeamF2', 'PrincetonBeamF3', 'Eigenmodes2013']
 43nElementsList = [1,2,4,8,16,32,64,128,256,512,1024]
 44# nElementsList = [8,32, 128]
 45nElements = 8
 46
 47betaList = [0,15,30,45,60,75,90]
 48betaDegree = 45
 49
 50caseList = [0,1,2,3,4] #case 0 not working for Geometrically exact beam
 51#case=2
 52
 53useGraphics = False
 54verbose = 1*0
 55
 56useEP = True #for geometrically exact beam node
 57if useEP:
 58    NodeClass = NodeRigidBodyEP
 59    initialRotationsGE = eulerParameters0
 60else: #does not work for static case, as static solver currently (2023-04) cannot solve for Lie group nodes
 61    NodeClass = NodeRigidBodyRotVecLG
 62    initialRotationsGE = [0,0,0]
 63
 64
 65bodyFixedLoad = False
 66testErrorSum = 0
 67case=4
 68
 69printCase = True
 70#for nElements in nElementsList:
 71#for betaDegree in betaList:
 72for case in caseList:
 73#if True:
 74    if printCase:
 75        printCase=False
 76        exu.Print('case=', case, cases[case])
 77    mbs.Reset()
 78
 79    computeEigenmodes = False
 80    csFact = 1
 81    sectionData = exu.BeamSection()
 82    fTip = 0
 83    MxTip = 0
 84    MyTip = 0
 85
 86    ks1=1 #shear correction, torsion
 87    ks2=1 #shear correction, bending
 88    ks3=1 #shear correction, bending
 89    ff=1 #drawing factor
 90
 91    if case == 0 or case == 1:
 92        caseName = cases[case]
 93
 94        L = 2 #length of beam
 95        w = 0.1 #width of beam
 96        h = 0.5 #height Y
 97
 98        fTip = 5e5*h**3
 99        if case == 1:
100            fTip *= 1000
101
102        Em = 2.07e11
103        rho = 1e2
104
105        A=h*w
106        nu = 0.3              # Poisson ratio
107        ks2= 10*(1+nu)/(12+11*nu)
108        ks3=ks2
109
110    elif case == 2:
111        L = 2 #length of beam
112        h = 0.2 #height Y
113        w = 0.4 #width Z of beam
114        Em = 2.07e11
115        rho = 1e2
116
117        A=h*w
118
119        nu = 0.3              # Poisson ratio
120        ks1= 0.5768 #torsion correction factor if J=Jyy+Jzz
121        ks2= 0.8331
122        ks3= 0.7961
123
124        MxTip = 0.5e6
125        MyTip = 2e6
126
127        csFact = 10
128    elif case == 3 or case == 4: #Princeton beam example
129        L = 0.508       #length of beam
130        h = 12.3777e-3  #height Y; 12.3777e-3 with Obrezkov's paper
131        w = 3.2024e-3   #width Z of beam
132        Em = 71.7e9
133        ks1=0.198
134        nu = 0.31
135
136        ks2=1
137        ks3=1
138        # ks2=0.9
139        # ks3=0.9
140
141
142        rho = 1e2       #unused
143        A=h*w
144
145        MxTip = 0
146        MyTip = 0
147        if case == 3:
148            fTip = 8.896    #F2
149        elif case == 4:
150            fTip = 13.345 #F3
151        #if kk==0: exu.Print('load=', fTip)
152
153        beta = betaDegree/180*pi #beta=0 => negative y-axis
154        bodyFixedLoad = False
155
156        csFact = 10
157
158    Gm = Em/(2*(1+nu))      # Shear modulus
159
160    # Cross-section properties
161    Iyy = h*w**3/12 # Second moment of area of the beam cross-section
162    Izz = w*h**3/12 # Second moment of area of the beam cross-section
163    J = (Iyy+Izz)   # approximation; Polar moment of area of the beam cross-section
164
165    sectionData.stiffnessMatrix = np.diag([Em*A, Gm*A*ks2, Gm*A*ks3, Gm*J*ks1, Em*Iyy, Em*Izz])
166
167
168    rhoA = rho*A
169
170    if False:
171        #linear solution:
172        uzTip = fTip*L**3/(3*Em*Iyy)
173        exu.Print('uz linear=',uzTip)
174        uyTip = fTip*L**3/(3*Em*Izz)
175        exu.Print('uy linear=',uyTip)
176
177    sectionData.inertia= rho*J*np.eye(3)
178    sectionData.massPerLength = rhoA
179
180    sectionGeometry = exu.BeamSectionGeometry()
181
182    #points, in positive rotation sense viewing in x-direction, points in [Y,Z]-plane
183    #points do not need to be closed!
184    lp = exu.Vector2DList()
185    if True:
186        lp.Append([h*ff,-w*ff])
187        lp.Append([h*ff,w*ff])
188        lp.Append([-h*ff,w*ff])
189        lp.Append([-h*ff,-w*ff])
190
191    sectionGeometry.polygonalPoints = lp
192    #exu.Print('HERE\n',sectionGeometry.polygonalPoints)
193    nGround = mbs.AddNode(NodePointGround(referenceCoordinates=[0,0,0])) #ground node for coordinate constraint
194    mnGround = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nGround, coordinate=0))
195
196
197    eY=[0,1,0]
198    eZ=[0,0,1]
199    lElem = L/nElements
200    useGeometricallyExact = True
201    if compute3D:
202        if useGeometricallyExact:
203            n0 = mbs.AddNode(NodeClass(referenceCoordinates=[0,0,0]+initialRotationsGE))
204        else:
205            initialRotations = eY+eZ
206            n0 = mbs.AddNode(NodePointSlope23(referenceCoordinates=[0,0,0]+initialRotations))
207        nInit = n0
208        for k in range(nElements):
209            if useGeometricallyExact:
210                n1 = mbs.AddNode(NodeClass(referenceCoordinates=[lElem*(k+1),0,0]+initialRotationsGE))
211
212                oBeam = mbs.AddObject(ObjectBeamGeometricallyExact(nodeNumbers=[n0,n1], physicsLength = lElem,
213                                                                     sectionData = sectionData,
214                                                                     visualization=VBeam3D(sectionGeometry=sectionGeometry)))
215            else:
216                n1 = mbs.AddNode(NodePointSlope23(referenceCoordinates=[lElem*(k+1),0,0]+initialRotations))
217                oBeam = mbs.AddObject(ObjectANCFBeam(nodeNumbers=[n0,n1], physicsLength = lElem,
218                                                       #testBeamRectangularSize = [h,w],
219                                                       sectionData = sectionData,
220                                                       crossSectionPenaltyFactor = [csFact,csFact,csFact],
221                                                       visualization=VANCFBeam(sectionGeometry=sectionGeometry)))
222            n0 = n1
223
224
225        mTip = mbs.AddMarker(MarkerNodeRigid(nodeNumber = n1))
226        if fTip != 0:
227            if case < 3:
228                mbs.AddLoad(Force(markerNumber=mTip, loadVector = [0,fTip,0], bodyFixed = bodyFixedLoad))
229            elif case >= 3:
230                mbs.AddLoad(Force(markerNumber=mTip, loadVector = [0,-fTip*cos(beta),fTip*sin(beta)], bodyFixed = bodyFixedLoad))
231
232        if MxTip != 0 or MyTip != 0:
233            mbs.AddLoad(Torque(markerNumber=mTip, loadVector = [MxTip, MyTip,0]))#, bodyFixed = True ))
234
235        if useGeometricallyExact:
236            nm0 = mbs.AddMarker(MarkerNodeRigid(nodeNumber=nInit))
237            nmGround = mbs.AddMarker(MarkerNodeRigid(nodeNumber=nGround))
238            mbs.AddObject(GenericJoint(markerNumbers=[nmGround, nm0]))
239        else:
240            for i in range(9):
241                #if i != 4 and i != 8: #exclude constraining the slope lengths
242                if True:
243                    nm0 = mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=nInit, coordinate=i))
244                    mbs.AddObject(CoordinateConstraint(markerNumbers=[mnGround, nm0]))
245
246
247    # exu.Print(mbs)
248    mbs.Assemble()
249
250    tEnd = 100     #end time of simulation
251    stepSize = 0.5*0.01*0.1    #step size; leads to 1000 steps
252
253    simulationSettings = exu.SimulationSettings()
254    simulationSettings.solutionSettings.solutionWritePeriod = 2e-2  #output interval general
255    simulationSettings.solutionSettings.sensorsWritePeriod = 1e-1  #output interval of sensors
256    simulationSettings.timeIntegration.numberOfSteps = int(tEnd/stepSize) #must be integer
257    simulationSettings.timeIntegration.endTime = tEnd
258    #simulationSettings.solutionSettings.solutionInformation = "This is the info\nNew line\n and another new line \n"
259    simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.5
260    #simulationSettings.timeIntegration.simulateInRealtime=True
261    #simulationSettings.timeIntegration.realtimeFactor=0.1
262
263    simulationSettings.timeIntegration.verboseMode = verbose
264    simulationSettings.staticSolver.verboseMode = verbose
265
266    #simulationSettings.parallel.numberOfThreads = 4
267    simulationSettings.timeIntegration.newton.useModifiedNewton = True
268    #simulationSettings.timeIntegration.newton.numericalDifferentiation.minimumCoordinateSize = 1e0
269
270    #simulationSettings.timeIntegration.newton.numericalDifferentiation.relativeEpsilon = 1e-4
271    simulationSettings.timeIntegration.newton.relativeTolerance = 1e-6
272
273    # simulationSettings.displayComputationTime = True
274    simulationSettings.linearSolverType = exu.LinearSolverType.EigenSparse
275    # simulationSettings.parallel.numberOfThreads = 4
276
277    #simulationSettings.staticSolver.newton.numericalDifferentiation.relativeEpsilon = 5e-5
278    #simulationSettings.staticSolver.newton.numericalDifferentiation.forODE2 = True
279    #simulationSettings.staticSolver.newton.relativeTolerance = 1e-6
280    # simulationSettings.staticSolver.newton.numericalDifferentiation.relativeEpsilon = 1e-4
281
282    simulationSettings.staticSolver.numberOfLoadSteps = 5
283    simulationSettings.staticSolver.adaptiveStep = True
284    #simulationSettings.staticSolver.stabilizerODE2term = 100
285
286    if useGeometricallyExact:
287        # simulationSettings.staticSolver.newton.numericalDifferentiation.forODE2 = True
288        # simulationSettings.staticSolver.newton.numericalDifferentiation.relativeEpsilon = 1e-5
289        # simulationSettings.staticSolver.newton.relativeTolerance = 1e-5
290        # simulationSettings.staticSolver.newton.absoluteTolerance = 1e-5
291        if case == 0:
292            simulationSettings.staticSolver.newton.relativeTolerance = 1e-4
293            simulationSettings.staticSolver.newton.absoluteTolerance = 1e-5
294            simulationSettings.staticSolver.numberOfLoadSteps = 1 #otherwise makes problems
295
296    if nElements > 32 and case==0: #change tolerance, because otherwise no convergence
297        simulationSettings.staticSolver.newton.relativeTolerance = 1e-6
298    if case == 1: #tolerance changed from 1e-8 to 5e-10 to achieve values of paper (1024 has difference at last digit in paper)
299        simulationSettings.staticSolver.newton.relativeTolerance = 0.5e-9
300
301
302
303    #add some drawing parameters for this example
304    SC.visualizationSettings.nodes.drawNodesAsPoint=False
305    SC.visualizationSettings.nodes.defaultSize=0.01
306
307    SC.visualizationSettings.bodies.beams.axialTiling = 50
308    SC.visualizationSettings.general.drawWorldBasis = True
309    SC.visualizationSettings.general.worldBasisSize = 0.1
310    SC.visualizationSettings.openGL.multiSampling = 4
311
312
313    # [M, K, D] = exu.solver.ComputeLinearizedSystem(mbs, simulationSettings, useSparseSolver=True)
314    # exu.Print('M=',M.round(1))
315
316    if useGraphics:
317        exu.StartRenderer()
318        mbs.WaitForUserToContinue()
319
320    # if computeEigenmodes:
321    #     nModes = 3*(1+int(compute3D))
322    #     nRigidModes = 3*(1+int(compute3D))
323    #     if compute2D:
324    #         constrainedCoordinates=[0,1,mbs.systemData.ODE2Size()-2]
325    #     else:
326    #         constrainedCoordinates=[0,1,2,5,mbs.systemData.ODE2Size()-8,mbs.systemData.ODE2Size()-7]
327
328    #     # constrainedCoordinates=[]
329
330    #     compeig=mbs.ComputeODE2Eigenvalues(simulationSettings, useSparseSolver=False,
331    #                                 numberOfEigenvalues= nRigidModes+nModes,
332    #                                 constrainedCoordinates=constrainedCoordinates,
333    #                                 convert2Frequencies= False)
334
335    #     exu.Print('eigvalues=',np.sqrt(compeig[0][nRigidModes:]))
336
337    #     if False: #show modes:
338    #         for i in range(nModes):
339    #             iMode = nRigidModes+i
340    #             mbs.systemData.SetODE2Coordinates(5*compeig[1][:,iMode], exudyn.ConfigurationType.Visualization)
341    #             mbs.systemData.SetTime(np.sqrt(compeig[0][iMode]), exudyn.ConfigurationType.Visualization)
342    #             mbs.SendRedrawSignal()
343
344    #             mbs.WaitForUserToContinue()
345
346    # else:
347    mbs.SolveStatic(simulationSettings)
348    # mbs.SolveDynamic(simulationSettings)
349    #mbs.SolveDynamic(simulationSettings, solverType = exu.DynamicSolverType.RK44)
350
351    #check jacobian
352    if False:
353    #%%+++++++++++++++++++++++++++++++++++
354        solver=mbs.sys['staticSolver']
355        solver.InitializeSolver(mbs, simulationSettings)
356        solver.ComputeJacobianODE2RHS(mbs)
357        J=solver.GetSystemJacobian()
358        print((1e-6*J[:14,:7]).round(3))
359        print((1e-6*J[:14,7:14]).round(3))
360
361    #%%+++++++++++++++++++++++++++++++++++
362    if useGraphics:
363        SC.WaitForRenderEngineStopFlag()
364        exu.StopRenderer() #safely close rendering window!
365
366    ##evaluate final (=current) output values
367    uTip = mbs.GetNodeOutput(n1, exu.OutputVariableType.Displacement)
368
369    errorFact = 1
370    if case != 1:
371        errorFact *= 100
372
373    testErrorSum += np.linalg.norm(uTip)
374
375
376
377    if case < 2:
378        pTip = mbs.GetNodeOutput(n1, exu.OutputVariableType.Position)
379        exu.Print('ne=',nElements, ', ux=',L-pTip[0], ', uy=',pTip[1])
380    elif case == 2:
381        rotTip = mbs.GetNodeOutput(n1, exu.OutputVariableType.Rotation)
382        exu.Print('ne=',nElements, ', u=',list(uTip))
383        # exu.Print('ne=',nElements, ', rot=',rotTip)
384    elif case == 3 or case == 4:
385        exu.Print('ne=', nElements, ', beta=', round(beta*180/pi,1), ', u=',uTip.round(7))
386
387
388exu.Print('Solution of geometricallyExactBeamTest=', testErrorSum)
389exudynTestGlobals.testError = testErrorSum - (1.012822053539261)
390exudynTestGlobals.testResult = testErrorSum
391
392
393#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
394#all results are taken from ANCFBeam (shear deformable 2-node 3D beam):
395#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
396
397# case= 0/CantileverLinear2011
398#NachbagauerPechsteinIrschikGerstmayrMUBO2011 (2D):
399# ne=1,   9.12273046e–8, 6.16666566e–4, 0.000193
400# ne=2,   1.61293091e–7, 7.61594059e–4, 4.831e–5
401# ne=4,   1.81763233e–7, 7.97825954e–4, 1.208e–5
402# ne=256, 1.88847418e–7, 8.09900305e–4, 2.945e–9
403#Exudyn: ksFact=1
404# ne= 1 , ux= 9.122730637578513e-08 , uy= 0.0006166665660910789
405# ne= 2 , ux= 1.612930911054633e-07 , uy= 0.0007615940599560586
406# ne= 4 , ux= 1.8176323512975046e-07 , uy= 0.0007978259537503566
407# ne= 8 , ux= 1.8706537496804287e-07 , uy= 0.0008068839288072378
408# ne= 16 , ux= 1.8840244964124508e-07 , uy= 0.0008091484226773518
409# ne= 32 , ux= 1.887374359021976e-07 , uy= 0.0008097145461515286
410# ne= 64 , ux= 1.888212299849812e-07 , uy= 0.0008098560770202866
411# ne= 128 , ux= 1.8884218011550047e-07 , uy= 0.000809891459736643
412# ne= 256 , ux= 1.8884741770364144e-07 , uy= 0.0008099003054122335
413
414
415# case= 1/Cantilever2011
416#NachbagauerPechsteinIrschikGerstmayrMUBO2011 (2D):
417# ne=1,    0.07140274, 0.54225823, 0.168310
418# ne=2,    0.12379212, 0.65687111, 0.053697
419# ne=4,    0.14346767, 0.69593561, 0.014633
420# ne=1024, 0.15097103, 0.71056837, 2.280e–7
421
422#Exudyn: ksFact=1
423# ne= 1 , ux= 0.07140273975041422 , uy= 0.5422582285449739
424# ne= 2 , ux= 0.12379212054619537 , uy= 0.6568711099777776
425# ne= 4 , ux= 0.14346766617229956 , uy= 0.695935613449867
426# ne= 8 , ux= 0.14904162148449163 , uy= 0.7068152604035266
427# ne= 16 , ux= 0.15048521526298897 , uy= 0.709623891842095
428# ne= 32 , ux= 0.15084943688011565 , uy= 0.7103320154655514
429# ne= 64 , ux= 0.15094070328691145 , uy= 0.7105094267817303
430# ne= 128 , ux= 0.15096353326024237 , uy= 0.7105538037895819
431# ne= 256 , ux= 0.15096924149743085 , uy= 0.7105648993600513
432# ne= 512 , ux= 0.15097066651939461 , uy= 0.7105676689547459
433# ne= 1024 , ux= 0.15097102364723924 , uy= 0.7105683631862169
434
435# case = 2:
436#2013 CND, Nachbagauer Gruber Gerstmayr (static, 3D); "Structural and Continuum Mechanics Approaches for a 3D Shear Deformable ANCF Beam Finite Element: Application to Static and Linearized Dynamic Examples"
437#Table 4:
438# SMF
439# 8,  1.0943e-4, 1.8638e-4, 1.8117e-2
440# 32, 1.0943e-4, 1.8625e-4, 1.8117e-2
441# ANSYS
442# 40, 1.0939e-4, 1.8646e-4, 1.8117e-2
443#Exudyn, ksFact=10:
444# ne= 8 , u= [-0.00010900977088157404, -0.0001902100873246334, -0.01811732779800177]
445# ne= 32 , u= [-0.00010941122286522997, -0.00018667435478355072, -0.01811739809277171]
446# ne= 128 , u= [-0.00010943631319815239, -0.000186451835025629, -0.018117402461210096]
447#==> in 2013 paper, element performed slightly better, especially in ux and uy terms
448
449# case = 3:
450#Princeton beam with ANSYS (Leonid Obrezkov / Aki Mikkola / Marko Matikainen et al.,
451#       Performance review of locking alleviation methods for continuum ANCF beam elements,
452#       Nonlinear Dynamics, Vol. 109, pp. 31–546, May 2022
453# beta=[0 15 30 45 60 75 90];
454if (case==3 or case == 4) and False:
455    # F2=8.896
456    # % ANSYS beam (10-199 el)
457    ANSYSF2y=np.array([1.071417630E-002,  1.061328706E-002, 1.011169630E-002,  8.837226265E-003, 6.604665004E-003, 3.538889001E-003, 0])
458    ANSYSF2z=np.array([0, 4.208232124E-002, 7.939482948E-002, 0.108987937,  0.129887616, 0.142194370, 0.146245978])
459    exu.Print('refsol ANSYS F2=8.896:\n',ANSYSF2y.round(6), '\n', ANSYSF2z.round(6))
460    # % ANSYS solid (el) (4x12x500) - finer mesh doesn't have much influence see in Size effect file
461    # ANSYS_solid_y=[1.069752828E-002 1.057180106E-002 9.938278402E-003 8.686786771E-003 6.500006282E-003 3.481999513E-003 0];
462    # ANSYS_solid_z=[0 4.101165651E-002 7.696749069E-002 0.105976311 0.127251299 0.139594740 0.143848652];
463
464    # F3=13.345
465    # % ANSYS beam (10-199 el)
466    ANSYSF3y=np.array([1.606423724E-002, 1.645825752E-002, 1.665873206E-002, 1.518618440E-002, 1.157837500E-002, 6.248967384E-003, 0])
467    ANSYSF3z=np.array([0,                6.435812858E-002, 0.117735994,      0.156467239,      0.181861627,      0.196097131,      0.200677707])
468    # % ANSYS solid (el) (4x12x500) - finer mesh see in Size effect file
469    #ANSYS_solid_y=[1.603700622E-002 1.637026068E-002 1.640440775E-002 1.485055210E-002 1.127173264E-002 6.062461977E-003  0])
470    #ANSYS_solid_z=[0 6.270699533E-002 0.113752002 0.153554457 0.179978534  0.192972233 0.197669499])
471    exu.Print('refsol ANSYS F3=13.345:\n',ANSYSF3y.round(6), '\n', ANSYSF3z.round(6))
472#Exudyn results for Princeton beam:
473#not exactly the same, but around the previous values with HOTINT
474#using 16 elements, csFact=10 (no influence)
475# F2=8.896
476# case= 3, PrincetonBeam
477# ne= 16 , beta= 0.0 , u= [-0.0001352 -0.0107023  0.       ]
478# ne= 16 , beta= 15.0 , u= [-0.0022414 -0.0106295  0.0421374]
479# ne= 16 , beta= 30.0 , u= [-0.0076567 -0.0101861  0.0794434]
480# ne= 16 , beta= 45.0 , u= [-0.0143664 -0.0089529  0.1089703]
481# ne= 16 , beta= 60.0 , u= [-0.0204225 -0.0067182  0.1297877]
482# ne= 16 , beta= 75.0 , u= [-0.0245093 -0.0036079  0.1420319]
483# ne= 16 , beta= 90.0 , u= [-0.0259403 -0.         0.1460608]
484
485# F3=13.345
486# case= 4, PrincetonBeam
487# ne= 16 , beta= 0.0 , u= [-0.0003039 -0.0160454  0.       ]
488# ne= 16 , beta= 15.0 , u= [-0.005319  -0.0165469  0.064622 ]
489# ne= 16 , beta= 30.0 , u= [-0.0171901 -0.0169316  0.1179818]
490# ne= 16 , beta= 45.0 , u= [-0.0303357 -0.0155488  0.1565214]
491# ne= 16 , beta= 60.0 , u= [-0.0411035 -0.0118996  0.1817173]
492# ne= 16 , beta= 75.0 , u= [-0.0479101 -0.0064334  0.1958343]
493# ne= 16 , beta= 90.0 , u= [-0.0502184 -0.         0.2003738]