New question #683543 on Yade: https://answers.launchpad.net/yade/+question/683543
Hello, I want to run the undrained triaxial test and I have tried two servo control mechanism. One control mechanism works but the other doesn't. So I want to ask why one works but the other doesn't while they seemed same to me. 1. run "servo()" that I defined every step in the O.engine, this method doesn't work t0=O.time O.cell.trsf=Matrix3.Identity O.engines=[ ForceResetter(), InsertionSortCollider([Bo1_Sphere_Aabb()]), InteractionLoop( [Ig2_Sphere_Sphere_ScGeom()], [Ip2_FrictMat_FrictMat_FrictPhys()], [Law2_ScGeom_FrictPhys_CundallStrack()]), NewtonIntegrator(damping=0.05), GlobalStiffnessTimeStepper(), PyRunner(command='servo', iterPeriod=1),] def servo(): ratex=-0.05 ratey=0.5*sqrt(1-0.05*(O.time-t0))*0.05/(1-0.05*(O.time-t0))/(1-0.05*(O.time-t0)) # derivative to time, d(sqrt(1/1-0.05*t))/dt ratez=0.5*sqrt(1-0.05*(O.time-t0))*0.05/(1-0.05*(O.time-t0))/(1-0.05*(O.time-t0)) # derivative to time, d(sqrt(1/1-0.05*t))/dt O.cell.velGrad=Matrix3(ratex,0,0,0,ratey,0,0,0,ratez) 2. do not run "servo" that I defined, instead, just add two sentences at the end of the script, this method works O.engines=[ ForceResetter(), InsertionSortCollider([Bo1_Sphere_Aabb()]), InteractionLoop( [Ig2_Sphere_Sphere_ScGeom()], [Ip2_FrictMat_FrictMat_FrictPhys()], [Law2_ScGeom_FrictPhys_CundallStrack()]), NewtonIntegrator(damping=0.05), GlobalStiffnessTimeStepper(),] O.cell.trsf=Matrix3.Identity O.cell.velGrad=Matrix3(-0.05, 0, 0, 0, 0.025, 0, 0, 0, 0.025) In the first servo control mechanism, the volume continues to increase, which is wrong. In the second mechanism, the volume only decreases negligibly, which is right. If I put the O.cell.trsf=Matrix3.Identity in the "servo" in the first method, do you think it can work? Do you know the reason for this? Thank you! Regards, Yuxuan -- 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