rigid3Dexample.py

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  1#%%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2# This is an EXUDYN example
  3#
  4# Details:  A chain of 3D rigid bodies is simulated rigid bodies are connected via spring-dampers (no joints!)
  5#
  6# Author:   Johannes Gerstmayr
  7# Date:     2019-11-15
  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.itemInterface import *
 15from exudyn.utilities import * #includes itemInterface and rigidBodyUtilities
 16import exudyn.graphics as graphics #only import if it does not conflict
 17
 18SC = exu.SystemContainer()
 19mbs = SC.AddSystem()
 20
 21print('EXUDYN version='+exu.GetVersionString())
 22
 23#%%+++++++++++++++++++++++++++++++++++
 24#background
 25#rect = [-0.1,-0.1,0.1,0.1] #xmin,ymin,xmax,ymax
 26#background0 = {'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
 27color = [0.1,0.1,0.8,1]
 28zz = 2*3 #max size
 29s = 0.1 #size of cube
 30sx = 3*s #x-size
 31cPosZ = 0.1 #offset of constraint in z-direction
 32
 33#create background, in order to have according zoom all
 34# background0 = GraphicsDataRectangle(-zz,-2*zz,zz,zz,graphics.color.white)
 35background0 = graphics.CheckerBoard(point=[0,-0.5*zz,-0.25*zz],size=6*zz)
 36oGround=mbs.CreateGround(referencePosition= [0,0,0],
 37                         graphicsDataList = [background0])
 38mPosLast = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround,
 39                                            localPosition=[-2*sx,0,cPosZ]))
 40
 41#%%+++++++++++++++++++++++++++++++++++
 42#create a chain of bodies:
 43for i in range(20):
 44    #print("Build Object", i)
 45    f = 0 #factor for initial velocities
 46    omega0 = [0,50.*f,20*f] #arbitrary initial angular velocity
 47    ep0 = eulerParameters0 #no rotation
 48
 49    ep_t0 = AngularVelocity2EulerParameters_t(omega0, ep0)
 50
 51    p0 = [-sx+i*2*sx,0.,0] #reference position
 52    v0 = [0.2*f,0.,0.] #initial translational velocity
 53
 54    nRB = mbs.AddNode(NodeRigidBodyEP(referenceCoordinates=p0+ep0,
 55                                      initialVelocities=v0+list(ep_t0)))
 56    oGraphicsLines = GraphicsDataOrthoCubeLines(-0.9*sx,-s,-s, 0.9*sx,s,s, color=graphics.color.black)
 57    oGraphics = graphics.Brick(size=[1.8*sx, 2*s, 2*s], color= graphics.color.dodgerblue)
 58    oGraphicsJoint = graphics.Sphere(point=[-sx,0,cPosZ], radius = 0.6*s, color=graphics.color.darkgrey, nTiles=24)
 59    oRB = mbs.AddObject(ObjectRigidBody(physicsMass=2,
 60                                        physicsInertia=[6,1,6,0,0,0],
 61                                        nodeNumber=nRB,
 62                                        visualization=VObjectRigidBody(graphicsData=[oGraphics, oGraphicsJoint, oGraphicsLines])))
 63
 64    mMassRB = mbs.AddMarker(MarkerBodyMass(bodyNumber = oRB))
 65    mbs.AddLoad(Gravity(markerNumber = mMassRB, loadVector=[0.,-9.81,0.])) #gravity in negative z-direction
 66
 67    k = 1e7
 68    d=0.01*k
 69    mPos = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oRB, localPosition = [-sx,0.,cPosZ]))
 70    mbs.AddObject(ObjectConnectorCartesianSpringDamper(markerNumbers = [mPosLast, mPos],
 71                                                       stiffness=[k,k,k], damping=[d,d,d])) #gravity in negative z-direction
 72    mPosLast = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oRB, localPosition = [sx,0.,cPosZ]))
 73
 74#%%+++++++++++++++++++++++++++++++++++
 75mbs.Assemble()
 76print(mbs)
 77
 78simulationSettings = exu.SimulationSettings() #takes currently set values or default values
 79
 80fact = 20000 #10000
 81simulationSettings.timeIntegration.numberOfSteps = 1*fact
 82simulationSettings.timeIntegration.endTime = 0.001*fact*0.5*4
 83simulationSettings.solutionSettings.solutionWritePeriod = simulationSettings.timeIntegration.endTime/fact*10
 84simulationSettings.timeIntegration.verboseMode = 1
 85
 86simulationSettings.timeIntegration.newton.useModifiedNewton = True
 87simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.6 #0.6 works well
 88simulationSettings.linearSolverType = exu.LinearSolverType.EigenSparse
 89
 90simulationSettings.solutionSettings.solutionInformation = "rigid body tests"
 91SC.visualizationSettings.nodes.defaultSize = 0.05
 92SC.visualizationSettings.openGL.multiSampling = 4
 93SC.visualizationSettings.openGL.lineWidth = 2
 94
 95# uncomment following line for shadow:
 96# SC.visualizationSettings.openGL.shadow = 0.5
 97# SC.visualizationSettings.openGL.light0position = [4,4,10,0]
 98
 99exu.StartRenderer()
100mbs.WaitForUserToContinue()
101
102mbs.SolveDynamic(simulationSettings)
103
104SC.WaitForRenderEngineStopFlag()
105exu.StopRenderer() #safely close rendering window!