compareFullModifiedNewton.py

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  1#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  pendulum example: check difference of full and modified newton
  5#
  6# Author:   Johannes Gerstmayr
  7# Date:     2020-06-19
  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 * #includes itemInterface and rigidBodyUtilities
 15import exudyn.graphics as graphics #only import if it does not conflict
 16
 17import numpy as np
 18import matplotlib.pyplot as plt
 19import matplotlib.ticker as ticker
 20
 21useGraphics = True #without test
 22#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 23#you can erase the following lines and all exudynTestGlobals related operations if this is not intended to be used as TestModel:
 24try: #only if called from test suite
 25    from modelUnitTests import exudynTestGlobals #for globally storing test results
 26    useGraphics = exudynTestGlobals.useGraphics
 27except:
 28    class ExudynTestGlobals:
 29        pass
 30    exudynTestGlobals = ExudynTestGlobals()
 31#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 32
 33SC = exu.SystemContainer()
 34mbs = SC.AddSystem()
 35
 36
 37#%%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 38#rigid pendulum:
 39rect = [-2,-2,2,2] #xmin,ymin,xmax,ymax
 40background = {'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
 41oGround=mbs.AddObject(ObjectGround(referencePosition= [0,0,0], visualization=VObjectGround(graphicsData= [background])))
 42a = 0.5     #x-dim of pendulum
 43b = 0.05    #y-dim of pendulum
 44massRigid = 12
 45inertiaRigid = massRigid/12*(2*a)**2
 46g = 9.81    # gravity
 47
 48graphics2 = {'type':'Line', 'color':[0.1,0.1,0.8,1], 'data':[-a,-b,0, a,-b,0, a,b,0, -a,b,0, -a,-b,0]} #background
 49omega0 = 5*0 #inconsistent initial conditions lead to integration problems!
 50nRigid = mbs.AddNode(Rigid2D(referenceCoordinates=[a,0,0], initialVelocities=[0,omega0*a,omega0]));
 51oRigid = mbs.AddObject(RigidBody2D(physicsMass=massRigid, physicsInertia=inertiaRigid,nodeNumber=nRigid,visualization=VObjectRigidBody2D(graphicsData= [graphics2])))
 52
 53mR1 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[-a,0.,0.])) #support point
 54mR2 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oRigid, localPosition=[ a,0.,0.])) #end point
 55
 56mG0 = mbs.AddMarker(MarkerBodyPosition(bodyNumber=oGround, localPosition=[0,0,0.]))
 57mbs.AddObject(RevoluteJoint2D(markerNumbers=[mG0,mR1]))
 58
 59mbs.AddLoad(Force(markerNumber = mR2, loadVector = [0, -massRigid*g, 0]))
 60
 61mbs.Assemble()
 62#exu.Print(mbs)
 63
 64simulationSettings = exu.SimulationSettings() #takes currently set values or default values
 65
 66simulationSettings.timeIntegration.numberOfSteps = 100 #100
 67simulationSettings.timeIntegration.endTime = 2
 68simulationSettings.timeIntegration.newton.relativeTolerance = 1e-8
 69simulationSettings.timeIntegration.newton.absoluteTolerance = 1e-4
 70simulationSettings.timeIntegration.verboseMode = 1
 71
 72simulationSettings.timeIntegration.newton.numericalDifferentiation.minimumCoordinateSize = 1
 73#simulationSettings.timeIntegration.generalizedAlpha.useNewmark = True
 74#simulationSettings.timeIntegration.generalizedAlpha.useIndex2Constraints = True
 75simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.5
 76simulationSettings.displayStatistics = True
 77simulationSettings.solutionSettings.solutionWritePeriod = 1e-4
 78
 79simulationSettings.timeIntegration.newton.useModifiedNewton = True
 80simulationSettings.solutionSettings.coordinatesSolutionFileName = "solution/modifiedNewton.txt"
 81mbs.SolveDynamic(simulationSettings)#, experimentalNewSolver=False)
 82
 83simulationSettings.timeIntegration.newton.useModifiedNewton = False
 84simulationSettings.solutionSettings.coordinatesSolutionFileName = "solution/fullNewton.txt"
 85mbs.SolveDynamic(simulationSettings)#, experimentalNewSolver=False)
 86
 87
 88#%%*****************************************
 89#post processing for mass point system
 90
 91dataM = np.loadtxt('solution/modifiedNewton.txt', comments='#', delimiter=',')
 92dataF = np.loadtxt('solution/fullNewton.txt', comments='#', delimiter=',')
 93
 94# exu.Print("solFullNewton     =",sum(abs(dataF[:,5])))
 95# exu.Print("solModifiedNewton =",sum(abs(dataM[:,5])))
 96
 97u=sum(abs(dataM[:,5]-dataF[:,5]))
 98exu.Print("compareFullModifiedNewton u=",u)
 99
100exudynTestGlobals.testError = u - (0.0001583478719999567 ) #2020-12-18: 0.0001583478719999567
101exudynTestGlobals.testResult = u
102
103import os
104os.remove('solution/modifiedNewton.txt')
105os.remove('solution/fullNewton.txt')
106
107if useGraphics:
108    # plt.plot(dataM[:,0], dataM[:,3+2], 'b-') #plot column i over column 0 (time)
109    # plt.plot(dataF[:,0], dataF[:,3+2], 'r-') #plot column i over column 0 (time)
110    plt.plot(dataF[:,0], dataF[:,5]-dataM[:,5], 'r-')
111
112    ax=plt.gca() # get current axes
113    ax.grid(True, 'major', 'both')
114    ax.xaxis.set_major_locator(ticker.MaxNLocator(10)) #use maximum of 8 ticks on y-axis
115    ax.yaxis.set_major_locator(ticker.MaxNLocator(10)) #use maximum of 8 ticks on y-axis
116    plt.tight_layout()
117    plt.show()