rigidRotor3Dnutation.py

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  1#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  Example with 3D rotor, test nutation with point force
  5#
  6# Author:   Johannes Gerstmayr
  7# Date:     2019-12-05
  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#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 12import sys
 13sys.path.append('../TestModels')            #for modelUnitTest as this example may be used also as a unit test
 14
 15import exudyn as exu
 16from exudyn.itemInterface import *
 17from exudyn.utilities import *
 18
 19import time
 20import numpy as np
 21
 22SC = exu.SystemContainer()
 23mbs = SC.AddSystem()
 24print('EXUDYN version='+exu.GetVersionString())
 25
 26m = 2                   #mass in kg
 27r = 0.5                 #radius for disc mass distribution
 28lRotor = 0.2            #length of rotor disk
 29k = 8000                 #stiffness of (all/both) springs in rotor in N/m
 30Jxx = 0.5*m*r**2        #polar moment of inertia
 31Jyyzz = 0.25*m*r**2 + 1/12.*m*lRotor**2      #moment of inertia for y and z axes
 32
 33omega0=np.sqrt(2*k/m) #linear system
 34
 35D0 = 0.002              #dimensionless damping
 36d = 2*omega0*D0*m       #damping constant in N/(m/s)
 37
 38omegaInitial = 0.1*omega0 #initial rotation speed in rad/s
 39
 40print('resonance frequency (rad/s)= '+str(omega0))
 41
 42tEnd = 50               #end time of simulation
 43steps = 20000         #number of steps
 44
 45
 46#user function for load
 47def userLoad(mbs, t, load):
 48    #time.sleep(0.005) #make simulation slower
 49    if t<0.01: print(load)
 50    if t>10 and t<10.05:
 51        return load
 52    else:
 53        return [0,0,0]
 54
 55
 56#draw RGB-frame at origin
 57p=[0,0,0]
 58lFrame = 0.8
 59tFrame = 0.01
 60backgroundX = GraphicsDataCylinder(p,[lFrame,0,0],tFrame,[0.9,0.3,0.3,1],12)
 61backgroundY = GraphicsDataCylinder(p,[0,lFrame,0],tFrame,[0.3,0.9,0.3,1],12)
 62backgroundZ = GraphicsDataCylinder(p,[0,0,lFrame],tFrame,[0.3,0.3,0.9,1],12)
 63#mbs.AddObject(ObjectGround(referencePosition= [0,0,0], visualization=VObjectGround(graphicsData= [backgroundX, backgroundY, backgroundZ])))
 64
 65#rotor is rotating around x-axis
 66ep0 = eulerParameters0 #no rotation
 67ep_t0 = AngularVelocity2EulerParameters_t([omegaInitial,0,0], ep0)
 68print(ep_t0)
 69
 70p0 = [0,0,0] #reference position
 71v0 = [0.,0.,0.] #initial translational velocity
 72
 73#node for Rigid2D body: px, py, phi:
 74n1=mbs.AddNode(NodeRigidBodyEP(referenceCoordinates = p0+ep0, initialVelocities=v0+list(ep_t0)))
 75
 76#ground nodes
 77nGround0=mbs.AddNode(NodePointGround(referenceCoordinates = [0,0,0]))
 78
 79#add mass point (this is a 3D object with 3 coordinates):
 80gRotor = GraphicsDataCylinder([-lRotor*0.5,0,0],[lRotor*0.5,0,0],r,[0.3,0.3,0.9,1],32)
 81gRotor3 = [backgroundX, backgroundY, backgroundZ]
 82rigid = mbs.AddObject(RigidBody(physicsMass=m, physicsInertia=[Jxx,Jyyzz,Jyyzz,0,0,0], nodeNumber = n1,
 83                                visualization=VObjectRigidBody2D(graphicsData=[gRotor]+gRotor3)))
 84
 85#marker for ground (=fixed):
 86groundMarker0=mbs.AddMarker(MarkerNodePosition(nodeNumber= nGround0))
 87
 88#marker for rotor axis and support:
 89rotorAxisMarker0 =mbs.AddMarker(MarkerBodyPosition(bodyNumber=rigid, localPosition=[0,0,0]))
 90
 91
 92#++++++++++++++++++++++++++++++++++++
 93mbs.AddObject(CartesianSpringDamper(markerNumbers=[groundMarker0, rotorAxisMarker0],
 94                                    stiffness=[k,k,k], damping=[d, d, d]))
 95
 96#add force/torque:
 97rotorRigidMarker =mbs.AddMarker(MarkerBodyRigid(bodyNumber=rigid, localPosition=[0,r,0]))
 98mbs.AddLoad(Force(markerNumber=rotorRigidMarker, loadVector=[0.3,0.2,0.1], loadVectorUserFunction = userLoad))
 99#mbs.AddLoad(Torque(markerNumber=rotorRigidMarker, loadVector=[torque,0,0]))
100
101#print(mbs)
102mbs.Assemble()
103#mbs.systemData.Info()
104
105simulationSettings = exu.SimulationSettings()
106simulationSettings.solutionSettings.solutionWritePeriod = 1e-2  #output interval
107simulationSettings.timeIntegration.numberOfSteps = steps
108simulationSettings.timeIntegration.endTime = tEnd
109simulationSettings.timeIntegration.generalizedAlpha.useIndex2Constraints = True
110simulationSettings.timeIntegration.generalizedAlpha.useNewmark = True
111
112simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 1
113
114
115#start solver:
116mbs.SolveDynamic(simulationSettings)
117
118exu.StartRenderer()              #start graphics visualization
119mbs.WaitForUserToContinue()    #wait for pressing SPACE bar to continue
120
121fileName = 'coordinatesSolution.txt'
122solution = LoadSolutionFile('coordinatesSolution.txt')
123AnimateSolution(mbs, solution, 5, 0.02)
124
125#SC.WaitForRenderEngineStopFlag()#wait for pressing 'Q' to quit
126exu.StopRenderer()               #safely close rendering window!
127
128
129###+++++++++++++++++++++++++++++++++++++++++++++++++++++
130#import matplotlib.pyplot as plt
131#import matplotlib.ticker as ticker
132#
133#if True:
134#    data = np.loadtxt('coordinatesSolution.txt', comments='#', delimiter=',')
135#    n=steps
136#    #plt.plot(data[:,2], data[:,3], 'r-') #numerical solution
137#    #plt.plot(data[:,0], data[:,2], 'b-') #numerical solution
138#    plt.plot(data[:,0], data[:,3], 'g-') #numerical solution
139#    #plt.plot(data[n-500:n-1,1], data[n-500:n-1,2], 'r-') #numerical solution
140#
141#    ax=plt.gca() # get current axes
142#    ax.grid(True, 'major', 'both')
143#    ax.xaxis.set_major_locator(ticker.MaxNLocator(10))
144#    ax.yaxis.set_major_locator(ticker.MaxNLocator(10))
145#    plt.tight_layout()
146#    plt.show()