Question #295666 on Yade changed: https://answers.launchpad.net/yade/+question/295666
Status: Answered => Open Seti is still having a problem: Thanks Bruno, Based on below input to triaxial test example( box size and grain size). My purpose to create dense sample ( initial void ratio 0.8 , porosity 0.44) However the void ratio is more than 2!!!!!! ( porosity 0.67) , I am not sure how I can control it P.S. :Is there any conflict with the number of spheres , size of spheres and size of box? How I can modify the code to reach to dense sample? Sorry for long script, I have to copy the tutorial here to make you sure, I did not do big changes! ###########33 # -*- coding: utf-8 -*- from yade import pack ############################################ ### DEFINING VARIABLES AND MATERIALS ### ############################################ # Batch execution nRead=utils.readParamsFromTable( num_spheres=60,# number of spheres len(O.bodies) to verify: 10006 = 10000 particles + 6 walls is correct compFricDegree = 22, # contact friction during the confining phase (1) unknownOk=True, isoForce=100000, # stress for the isotropic compression phase (1) conStress=100000 # confinement stress, for the deviatoric loading session (2) ) from yade.params import table num_spheres=table.num_spheres # number of spheres called from table targetPorosity = 0.44 #the porosity we want for the packing (3 specimens: (Ei,n) = (1,0.382), (2,0.387), (3,0.409) ) compFricDegree = table.compFricDegree # initial contact friction during the confining phase (will be decreased during the REFD compaction process) finalFricDegree = 22 # contact friction during the deviatoric loading rate=.01 # loading rate (strain rate) damp=0.5 # damping coefficient stabilityThreshold=0.001 # initial value: 0.001 key='_triax_drain-.01,0,anglefinal85,firstangle85_100,100,1000,100e10,unbala.01, damp0.5without cohision' # simulation's name here young=800e6 # contact stiffness k_n/Ds mn,mx=Vector3(-0.008,-0.008,-0.008),Vector3(0.008,0.008,0.00) # corners of the initial packing thick = 0.001 ## create materials for spheres and plates O.materials.append(FrictMat(young=young,poisson=0.3,frictionAngle=radians(compFricDegree),density=2600,label='spheres')) O.materials.append(FrictMat(young=young,poisson=0.3,frictionAngle=10,density=0,label='walls')) ## create walls around the packing walls=utils.aabbWalls([mn,mx],thickness=thick,oversizeFactor=1.5,material='walls') wallIds=O.bodies.append(walls) ## use a SpherePack object to generate a random loose particles packing sp=pack.SpherePack() sp.makeCloud(mn,mx,0.002,0,num_spheres,False,0.95,seed=1) sp.toSimulation(material='spheres') ############################ ### DEFINING ENGINES ### ############################ triax=TriaxialStressController( maxMultiplier=1.001, # spheres growing factor (fast growth), validated only when internalCompaction = True finalMaxMultiplier=1.00001, # spheres growing factor (slow growth), validated only when internalCompaction = True thickness = thick, ## switch stress/strain control using a bitmask. What is a bitmask, huh?! ## Say x=1 if stress is controlled on x, else x=0. Same for for y and z, which are 1 or 0. ## Then an integer uniquely defining the combination of all these tests is: mask = x*1 + y*2 + z*4 ## to put it differently, the mask is the integer whose binary representation is xyz, i.e. ## "100" (1) means "x", "110" (3) means "x and y", "111" (7) means "x and y and z", etc. stressMask = 7, #the value of confining stress for the intitial (growth) phase goal1=table.isoForce, goal2=table.isoForce, goal3=table.isoForce, max_vel=0.5, # validated only when internalCompaction = False m/s internalCompaction=True, # If true the confining pressure is generated by growing particles # Key=key # passed to the engine so that the output file will have the correct name ) newton=NewtonIntegrator(damping=damp) O.engines=[ ForceResetter(), InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]), InteractionLoop( [Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()], [Ip2_FrictMat_FrictMat_FrictPhys()], [Law2_ScGeom_FrictPhys_CundallStrack()] ), ## We will use the global stiffness of each body to determine an optimal timestep (see https://yade-dem.org/w/images/1/1b/Chareyre&Villard2005_licensed.pdf) GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=25,timestepSafetyCoefficient=0.8), triax, TriaxialStateRecorder(iterPeriod=50,file='WallStresses'+key), newton ] O.save('initial'+key+'.xml') #Display spheres with 2 colors for seeing rotations better #Gl1_Sphere.stripes=0 #if nRead==0: yade.qt.Controller(), yade.qt.View() print 'Number of elements: ', len(O.bodies) print 'Box Volume: ', triax.boxVolume print 'Wang,100kpa,22degree,old,' ####################################### ### APPLYING CONFINING PRESSURE ### ####################################### while 1: O.run(1000, True) #the global unbalanced force on dynamic bodies, thus excluding boundaries, which are not at equilibrium unb=unbalancedForce() #average stress #note: triax.stress(k) returns a stress vector, so we need to keep only the normal component meanS=(triax.stress(triax.wall_right_id)[0]+triax.stress(triax.wall_top_id)[1]+triax.stress(triax.wall_front_id)[2])/3 print 'unbalanced force:',unb,' mean stress: ',meanS print 'void ratio=',triax.porosity/(1-triax.porosity), 'porosity=', triax.porosity print 'mean stress of engine', triax.meanStress if unb<stabilityThreshold and abs(meanS-table.isoForce)/table.isoForce<0.1: #0.001 # if abs(triax.porosity-targetPorosity)<0.001: break O.save('confinedState'+key+'.xml') print "### Isotropic state saved ###" print 'current porosity=',triax.porosity print 'current void ratio=',triax.porosity/(1-triax.porosity) print 'Wang,100kpa,22degree,old,' ################################################### ### REACHING A SPECIFIED POROSITY PRECISELY ### ################################################### ## We will reach a prescribed value of porosity with the REFD algorithm ## (see http://dx.doi.org/10.2516/ogst/2012032 and ## http://www.geosyntheticssociety.org/Resources/Archive/GI/src/V9I2/GI-V9-N2-Paper1.pdf) #import sys #this is only for the flush() below while triax.porosity>targetPorosity: # # we decrease friction value and apply it to all the bodies and contacts compFricDegree = 0.95*compFricDegree setContactFriction(radians(compFricDegree)) print "\r Friction: ",compFricDegree," porosity:",triax.porosity, sys.stdout.flush() # # while we run steps, triax will tend to grow particles as the packing # # keeps shrinking as a consequence of decreasing friction. Consequently # # porosity will decrease O.run(500,1) O.save('compactedState'+key+'.xml') print "### Compacted state saved ###" print 'current porosity=',triax.porosity print 'current void ratio=',triax.porosity/(1-triax.porosity) print 'step that starts the deviatoric loading ', O.iter print 'Wang,100kpa,22degree,old,' ############################## ### DEVIATORIC LOADING ### ############################## #We move to deviatoric loading, let us turn internal compaction off to keep particles sizes constant triax.internalCompaction=False # Change contact friction (remember that decreasing it would generate instantaneous instabilities) #setContactFriction(radians(finalFricDegree)) setContactFriction(radians(22)) #set stress control on x and z, we will impose strain rate on y (5) triax.stressMask = 5 #now goal2 is the target strain rate triax.goal2=-rate #we assign constant stress to the other directions triax.goal1=table.conStress triax.goal3=table.conStress ##we can change damping here. What is the effect in your opinion? newton.damping=0.1 ##Save temporary state in live memory. This state will be reloaded from the interface with the "reload" button. O.saveTmp() while triax.strain[1] < 0: O.run(50); O.wait() -- You received this question notification because your team yade-users is an answer contact for Yade. _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp