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 *
16
17SC = exu.SystemContainer()
18mbs = SC.AddSystem()
19
20print('EXUDYN version='+exu.GetVersionString())
21
22#%%+++++++++++++++++++++++++++++++++++
23#background
24#rect = [-0.1,-0.1,0.1,0.1] #xmin,ymin,xmax,ymax
25#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
26color = [0.1,0.1,0.8,1]
27zz = 2*3 #max size
28s = 0.1 #size of cube
29sx = 3*s #x-size
30cPosZ = 0.1 #offset of constraint in z-direction
31
32#create background, in order to have according zoom all
33# background0 = GraphicsDataRectangle(-zz,-2*zz,zz,zz,color4white)
34background0 = GraphicsDataCheckerBoard(point=[0,-0.5*zz,-0.25*zz],size=6*zz)
35oGround=mbs.CreateGround(referencePosition= [0,0,0],
36 graphicsDataList = [background0])
37mPosLast = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oGround,
38 localPosition=[-2*sx,0,cPosZ]))
39
40#%%+++++++++++++++++++++++++++++++++++
41#create a chain of bodies:
42for i in range(20):
43 #print("Build Object", i)
44 f = 0 #factor for initial velocities
45 omega0 = [0,50.*f,20*f] #arbitrary initial angular velocity
46 ep0 = eulerParameters0 #no rotation
47
48 ep_t0 = AngularVelocity2EulerParameters_t(omega0, ep0)
49
50 p0 = [-sx+i*2*sx,0.,0] #reference position
51 v0 = [0.2*f,0.,0.] #initial translational velocity
52
53 nRB = mbs.AddNode(NodeRigidBodyEP(referenceCoordinates=p0+ep0,
54 initialVelocities=v0+list(ep_t0)))
55 oGraphicsLines = GraphicsDataOrthoCubeLines(-0.9*sx,-s,-s, 0.9*sx,s,s, color=color4black)
56 oGraphics = GraphicsDataOrthoCubePoint(size=[1.8*sx, 2*s, 2*s], color= color4dodgerblue)
57 oGraphicsJoint = GraphicsDataSphere(point=[-sx,0,cPosZ], radius = 0.6*s, color=color4darkgrey, nTiles=24)
58 oRB = mbs.AddObject(ObjectRigidBody(physicsMass=2,
59 physicsInertia=[6,1,6,0,0,0],
60 nodeNumber=nRB,
61 visualization=VObjectRigidBody(graphicsData=[oGraphics, oGraphicsJoint, oGraphicsLines])))
62
63 mMassRB = mbs.AddMarker(MarkerBodyMass(bodyNumber = oRB))
64 mbs.AddLoad(Gravity(markerNumber = mMassRB, loadVector=[0.,-9.81,0.])) #gravity in negative z-direction
65
66 k = 1e7
67 d=0.01*k
68 mPos = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oRB, localPosition = [-sx,0.,cPosZ]))
69 mbs.AddObject(ObjectConnectorCartesianSpringDamper(markerNumbers = [mPosLast, mPos],
70 stiffness=[k,k,k], damping=[d,d,d])) #gravity in negative z-direction
71 mPosLast = mbs.AddMarker(MarkerBodyPosition(bodyNumber = oRB, localPosition = [sx,0.,cPosZ]))
72
73#%%+++++++++++++++++++++++++++++++++++
74mbs.Assemble()
75print(mbs)
76
77simulationSettings = exu.SimulationSettings() #takes currently set values or default values
78
79fact = 20000 #10000
80simulationSettings.timeIntegration.numberOfSteps = 1*fact
81simulationSettings.timeIntegration.endTime = 0.001*fact*0.5*4
82simulationSettings.solutionSettings.solutionWritePeriod = simulationSettings.timeIntegration.endTime/fact*10
83simulationSettings.timeIntegration.verboseMode = 1
84
85simulationSettings.timeIntegration.newton.useModifiedNewton = True
86simulationSettings.timeIntegration.generalizedAlpha.spectralRadius = 0.6 #0.6 works well
87simulationSettings.linearSolverType = exu.LinearSolverType.EigenSparse
88
89simulationSettings.solutionSettings.solutionInformation = "rigid body tests"
90SC.visualizationSettings.nodes.defaultSize = 0.05
91SC.visualizationSettings.openGL.multiSampling = 4
92SC.visualizationSettings.openGL.lineWidth = 2
93
94# uncomment following line for shadow:
95# SC.visualizationSettings.openGL.shadow = 0.5
96# SC.visualizationSettings.openGL.light0position = [4,4,10,0]
97
98exu.StartRenderer()
99mbs.WaitForUserToContinue()
100
101mbs.SolveDynamic(simulationSettings)
102
103SC.WaitForRenderEngineStopFlag()
104exu.StopRenderer() #safely close rendering window!