Question #240275 on Yade changed: https://answers.launchpad.net/yade/+question/240275
Jan Stránský proposed the following answer: Hello Zhu, you can achive it (as you mentioned) by setting groupMask. Let me explain on your example: O.bodies[0].mask = 1 # 0b0001 O.bodies[1].mask = 2 # 0b0010 O.bodies[2].mask = 1 # 0b0001 O.bodies[3].mask = 2 # 0b0010 where 0bXXXX stands for number binary representation. The interaction of two bodies is avoided, if mask1&mask2==0, see [1], section "AND". You can play e.g. in IPython: a = 0b0001 b = 0b0010 a&b # etc.. so in your case, 1&1 = 1, 2&2 = 2, 1&2 = 0, so body pairs 0-2 and 1-3 will interact and no other pair. To achieve what you want, do something like O.bodies[0].mask = 0b11 # 3 O.bodies[1].mask = 0b01 # 1 O.bodies[2].mask = 0b11 # 3 O.bodies[3].mask = 0b10 # 2 in this case 3&1=1, 3&2=2, 3&3=3, 2&1=0, 2&2=2, 1&1=1. So all particles will interact witch each other, except the pairs with mask1=1 and mask2=2, as 1&2=0. I.e. particles 1 and 3 in your example will not interact with each other. Maybe we could improve the documentation about mask attribute a little.. cheers Jan [1] http://en.wikipedia.org/wiki/Bitwise_operation 2013/12/4 ZHU Huaxiang <[email protected]> > Question #240275 on Yade changed: > https://answers.launchpad.net/yade/+question/240275 > > Description changed to: > Hello all, > > I am doing a special biaxial test which only content Four particles laying > to be a rhombus, like this > > 1 > o > 2 o o 0 > o > 3 > > how can I avoid interaction between axial line particles 1 and 3 if they > contact? > > I already tried the 'mask' and 'avoidSelfInteractionMask' to cooperate, > as > > O.bodies[0].groupMask=1;O.bodies[2].groupMask=1 > O.bodies[1].groupMask=2;O.bodies[3].groupMask=2 > [engines]collider.avoidSelfInteractionMask=2 > > but when the 1,3 interaction is avoided it is also impossible to > establish interactions between two different mask's particles, then all > interaction will lose by using 'avoidSelfInteractionMask'. > > Do you have any idea to achieve that? thank you. > > > Huaxiang > > > here is my code > > ------------------------------------------------------------------------------------------------------- > > import math > from yade import plot > > conf=100000 > poisson=0.5 > kn=1.0e8 > E=kn/1.0 > ks=poisson*kn > rate=5e-4 > status=[0.0,0.0,0.0,0.0] > > > O.materials.append(FrictMat(young=E,poisson=poisson,frictionAngle=radians(99.0),density=2600,label='spheres')) > > O.materials.append(FrictMat(young=1.0e3*kn,poisson=0.3,frictionAngle=radians(99.0),density=0,label='walls')) > > > mn,mx=Vector3(-math.sqrt(2)-1,-math.sqrt(2)-1,-1.1),Vector3(math.sqrt(2)+1,math.sqrt(2)+1,1.1) > walls=utils.aabbWalls([mn,mx],thickness=0.001,material='walls') > wallIds=O.bodies.append(walls) > > O.bodies.append([ > > utils.sphere(center=(math.sqrt(2),0.0,0.0),radius=1.0,material='spheres'), > > utils.sphere(center=(0.0,math.sqrt(2),0.0),radius=1.0,material='spheres'), > > utils.sphere(center=(-math.sqrt(2),0.0,0.0),radius=1.0,material='spheres'), > utils.sphere((0.0,-math.sqrt(2),0.0),1.0,material='spheres') > ]) > > > for k in O.bodies: > if isinstance(k.shape, Sphere): k.state.blockedDOFs='zXY' > > O.dt=.5*utils.PWaveTimeStep() > O.usesTimeStepper=True > > > 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()] > ), > > GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8, > defaultDt=4*utils.PWaveTimeStep()), > NewtonIntegrator(damping=0.01), > ] > > O.dt=.5e-3*utils.PWaveTimeStep() > > def setVel(velX,velY): > O.bodies[0].state.vel=Vector3(velX,0.0,0.0) > O.bodies[1].state.vel=Vector3(-velX,0.0,0.0) > O.bodies[2].state.vel=Vector3(0.0,velY,0.0) > O.bodies[3].state.vel=Vector3(0.0,-velY,0.0) > > rateTmp=rate > while 1: > meanS=(abs(O.forces.f(1)[0])+abs(O.forces.f(3)[1])) > unb=unbalancedForce() > if rateTmp>0.0 and meanS>conf: > print 'convert' > rateTmp=-0.5*rateTmp > elif rateTmp<0.0 and meanS<conf: > print 'convert' > rateTmp=-0.5*rateTmp > setVel(rateTmp,rateTmp) > O.run(1, True) > unb=unbalancedForce() > meanS=(abs(O.forces.f(1)[0])+abs(O.forces.f(3)[1]))*0.5 > print 'unbalanced force:',unb,' mean stress: ',meanS > if unb<0.001 and abs(meanS-conf)/conf<0.005: > break > > plot.plots={'e2':'q'} > plot.plot() > raw_input('confining finish') > > ''' > ini=O.bodies[7].state.se3[0][1] > e22=0.0 > e11=0.0 > #rate=1e2*rate > while 1: > setVel(0.0,rate);e22+=rate > O.run(1,True) > while unbalancedForce()>0.001: > setVel(0.0,0.0) > O.run(1,True) > rateTmp=-0.5*rate > lateralS=(abs(O.forces.f(0)[0])+abs(O.forces.f(1)[0]))*0.5 > while abs(lateralS-conf)/conf>0.001: > lateralS=(abs(O.forces.f(0)[0])+abs(O.forces.f(1)[0]))*0.5 > if rateTmp>0.0 and lateralS>conf: > rateTmp=-0.5*rateTmp > elif rateTmp<0.0 and lateralS<conf: > rateTmp=-0.5*rateTmp > setVel(rateTmp,0.0) > O.run(1, True);e11+=rateTmp > lateralS=(abs(O.forces.f(0)[0])+abs(O.forces.f(1)[0]))*0.5 > print > O.forces.f(3)[1]-O.forces.f(1)[0],O.forces.f(1)[0],(ini-O.bodies[7].state.se3[0][1])/ini > plot.addData(e2=e22,e1=e11,q=O.forces.f(3)[1]-O.forces.f(1)[0],i=O.iter) > ''' > > rate=10.0*rate > adjust=math.cos(75.0*pi/180.0)/math.sin(75.0*pi/180.0)*rate*1e-1 > ini=O.bodies[7].state.se3[0][1] > e22=0.0 > e11=0.0 > rateX=0.0 > while 1: > lateralS=(abs(O.forces.f(0)[0])+abs(O.forces.f(1)[0]))*0.5 > if lateralS>conf: > adjust=-abs(adjust) > elif lateralS<conf: > adjust=abs(adjust) > rateX+=adjust > setVel(rateX,rate);e22+=rate > O.run(1,True) > while unbalancedForce()>0.01: > setVel(0.0,0.0) > O.run(1,True) > print > O.forces.f(3)[1]-O.forces.f(1)[0],O.forces.f(1)[0],(ini-O.bodies[7].state.se3[0][1])/ini,unbalancedForce() > plot.addData(e2=e22,e1=e11,q=O.forces.f(3)[1]-O.forces.f(1)[0],i=O.iter) > > -- > You received this question notification because you are a member of > yade-users, which is an answer contact for Yade. > > _______________________________________________ > Mailing list: https://launchpad.net/~yade-users > Post to : [email protected] > Unsubscribe : https://launchpad.net/~yade-users > More help : https://help.launchpad.net/ListHelp > -- You received this question notification because you are a member of yade-users, which is an answer contact for Yade. _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
